Seat Masts are a pain and a DUMB idea

[Smiley]

The cutting went well today and we cut high for the first stab and then took off another 12 mm to get it right. Its a STUPID idea that leaves little flexability to the rider and heaven forbid that one does not know exactly what saddle and cleat system they will settle on, just plain dumb idea.

This is a client bike, not mine, no way :)

[93legendti]

I agree.

[rePhil]

What about resale? How much adjustment is left after cutting?

[SoCalSteve]

The cutting went well today and we cut high for the first stab and then took off another 12 mm to get it right. Its a STUPID idea that leaves little flexability to the rider and heaven forbid that one does not know exactly what saddle and cleat system they will settle on, just plain dumb idea.

The Look 595 (which hasnt been cut down yet) has 3 cm (yeah, cm, no mm) of upward adjustment...Thats alot of adjusting up.

I am not saying its a great idea as I havent yet ridden a bike with one. I will eventually and then make my decision.

Just sayin'

Steve

PS: Smiley, glad the circumcision went well. Was their wine and cake afterwards? :banana:

[David Kirk]

The cutting went well today and we cut high for the first stab and then took off another 12 mm to get it right. Its a STUPID idea that leaves little flexability to the rider and heaven forbid that one does not know exactly what saddle and cleat system they will settle on, just plain dumb idea.

Say it again but louder.

dave

[Smiley]

The Look 595 (which hasnt been cut down yet) has 3 cm (yeah, cm, no mm) of upward adjustment...Thats alot of adjusting up.

I am not saying its a great idea as I havent yet ridden a bike with one. I will eventually and then make my decision.

Just sayin'

Steve

PS: Smiley, glad the circumcision went well. Was their wine and cake afterwards? :banana:

This Scott Frame has 1.5 cm of adjustment but still very Dumb. When adjusting since I had my size cycle parallel to the frame we cut it on the High side of the 1.5 cm so if she sells the frame she can sell it to a taller rider by 1.5 cm of seat mast, how dumb is that :)

[duke]

According to all the experts you can't be a racer boy without a seat mast. I think I am going to duct tape one on my Ottrott.
duke

[palincss]

The cutting went well today and we cut high for the first stab and then took off another 12 mm to get it right. Its a STUPID idea that leaves little flexability to the rider and heaven forbid that one does not know exactly what saddle and cleat system they will settle on, just plain dumb idea.

You're starting to sound like a cranky old iBOB, Smiley. The whole point is to make bikes throwaways, isn't it? Besides, I didn't think Kelly Bedford went in for that sort of nonsense.

[Smiley]

You're starting to sound like a cranky old iBOB, Smiley. The whole point is to make bikes throwaways, isn't it? Besides, I didn't think Kelly Bedford went in for that sort of nonsense.


No good custom builder worth their salt would buy into such stupidity :)

[palincss]

You mean, you have a bike other than a Kelly Bedford? Well, that was your first mistake.

[false_Aest]

Yinz guys are just being crotchety.

Yinz guys probably complained when they stopped putting lead in gas.

Yinz guys probably wrote letters to the president when rotary phones were phased out.

FWIW, Jerk's bikes look super-über-mega-ultra-dope with the seat mast and so do them there SpeedVagens (though I'm not really sure why those hippy west coast liberals have to spell it like the commies used to).

AND SERIOUSLY, It's not a car unless you have to get out and turn the crank in front before you can drive the thing.



*grumble* stupid inflatable tires.

[sailorboy]

Yea, I guess its not for you if you don't have a clue what saddle you prefer (had the same one for I dunno, 6 years?) and same thing about your pedals...yea, maybe I'll just try a totally new pedal system for the first time in several years and swap out 6 pairs of 'em. oh and while I'm at it, I'll change my saddle height by more than 1.5cm cause what I've been riding is totally wrong; or maybe I'll grow my legs a little bit.

maybe not for every bike I own, but the whole 'racer boy' comment is not the issue. If you aren't still figuring out your size, what is wrong with this design?

[mike p]

Yinz, must be from around pittsburgh.

Mike





Yinz guys are just being crotchety.

Yinz guys probably complained when they stopped putting lead in gas.

Yinz guys probably wrote letters to the president when rotary phones were phased out.

FWIW, Jerk's bikes look super-über-mega-ultra-dope with the seat mast and so do them there SpeedVagens (though I'm not really sure why those hippy west coast liberals have to spell it like the commies used to).

AND SERIOUSLY, It's not a car unless you have to get out and turn the crank in front before you can drive the thing.



*grumble* stupid inflatable tires.

[bikemoore]

How about the fact that I couldn't fit one into my bike bag or box? Or sell it somebody a little taller? Granted, unless you pack your bike or sell them often, its not much of an issue.

Here's another one: I couldn't hook my son's trail-behind bike behind me with an integrated seat mast. Blasphemy to pull my kid behind me on my race bike? Only someone without little kids would dare think that.

If you look at the gain of integrated seatmast against the flexibility in use that you are giving up.....I won't buy a bike with integrated seat mast.

Dumb idea. OK for pros (maybe), but dumb for retail.

[Lifelover]

Yea, I guess its not for you if you don't have a clue what saddle you prefer (had the same one for I dunno, 6 years?) and same thing about your pedals...yea, maybe I'll just try a totally new pedal system for the first time in several years and swap out 6 pairs of 'em. oh and while I'm at it, I'll change my saddle height by more than 1.5cm cause what I've been riding is totally wrong; or maybe I'll grow my legs a little bit.

maybe not for every bike I own, but the whole 'racer boy' comment is not the issue. If you aren't still figuring out your size, what is wrong with this design?


It's the classic solution looking for a problem.

What possible advantage can it provide other than looking really cool!

And it definitely is a "racer boy" thing.

[caleb]

Granted, unless you pack your bike or sell them often, its not much of an issue.


I wouldn't ever buy a bike because of its resale value, and airline fees are becoming prohibitively expensive for flying with a bike.

Although I don't own one, I wouldn't rule it out. As long as you know what you want, I don't see a big down side.

[David Kirk]

I've never had anyone ever tell me the benefit of the system. Looking cool is cool but what does it do?

Dave

[Keith A]

I've never had anyone ever tell me the benefit of the system. Looking cool is cool but what does it do?Looks cool :rolleyes:

[Joe Cyclist]

I've never had anyone ever tell me the benefit of the system. Looking cool is cool but what does it do?

Dave

LBS told me that for carbon frames, it gives the builder more control over how the bike feels in regards to stiffness or compliance.

Sounded good and it looks cool, but still could not bring myself to buy one.

[bigman]

Marketing Hype in this case equals stupidity.

[Jack Brunk]

I think the ISP is a terrific addition to a really good frame. To each his own. Everyone should try one before they say they don't like them.

[David Kirk]

I think the ISP is a terrific addition to a really good frame. To each his own. Everyone should try one before they say they don't like them.

I don't disagree at all. I still don't know what it does or does better.

dave

[ThirtyEast]

I just got my first bike with an ISP. Like it. It hasn't made anything more difficult and I think it makes the bike look pretty slick.

Oh, and my Bedford IS going to have an ISP. This is no joke.

[Spud]

I am not a builder but I work on alot of highend bikes, I have built dozens of these bikes of various designs some better than others (Time, Look, Trek, Giant as a few). I started off thinking it was a solution to a problem that didn't exist and the first one i did was a little slow to build but if you build the bike to the fit it's not that hard and I usually cut 5mm lower to leave room for minor pick up fit adjusting or saddle changes made by the owner later.

I have been told by frame makers who have them is that it makes it easier to tie end the front end to the rear for torsional rigidity. I own a Meivici and I have ridden pratically all the major brands that have ISM and I can't tell if it really acheives it or not, perhaps if it does it needs to be measured by machines (i.e.8% may be tough to feel but it is still a substantial improvement).

[Jack Brunk]

There's a firmness/stability feeling underneath me when I'm on an ISP bike. Don't kow why or if it's real but it sure feels that way.

[labratmatt]

Seat masts are so stupid. The Trek system is slightly better, but it's still stupid. These big manufactures were running low on marketing material one day and someone had a "brilliant" idea. I seriously doubt the seat masts stick around for more than another threeish years.

[dogdriver]

One of the rocket scientists at Trek told me that a traditional seat post configuration on a carbon frame inhibits the frame from doing what they want it to (he had a big word for this, it escapes me) at the junction of the TT/ST/seat stay by inserting a stiff post into a structure that is supposed to move. The mast allows them to maintain control over the function of that portion of the frame. He also said it looked "righteous" (his word).

What do I know-- I own six bikes (please don't remind my wife of this, she only has two) made of various metals.

Just passing on what I heard, Chris

[learlove]

FWIW I'm in the ISP/seat mast are useless crowd. then again I think compact/sloping tt bikes (with the exception of "sightly sloping") look like the girls 10 speed my sister had when we were kids.

[znfdl]

No good custom builder worth their salt would buy into such stupidity :)

How about Speedvagen? Sasha defintely is not stupid.... Just sayin...

[false_Aest]

I like the tubular vs clincher debate more.

[znfdl]

I like the tubular vs clincher debate more.

What is a tubular? ;)

[peanutgallery]

Won't judge either way, it does look cool but it raises questions.

How do you set them up for sale in a shop? Leave the seat height jacked to the moon. Test rides? Availability of the small parts for the seat mast when the more volatile bike companies get on the bandwagon. They are light, new and probably prone to something they haven't figured out yet.

I was also thinking about those guys/gals that push your buttons when looking at bikes on the sales floor and never breaking out the wallet. "I like the bike, but before I spend the cash can you set it up for me?"

I see it on a custom or special order job for a keeper, but not something on the sales floor.

[soulspinner]

I don't disagree at all. I still don't know what it does or does better.

dave

At first they sold cabon posts saying they could be more absorbant(sounds like a paper towel) of vibration, the longer the post the better. Then ISP design comes along and says its stiffer. Ive just been using a Thomson post... :D

[Smiley]

Won't judge either way, it does look cool but it raises questions.

How do you set them up for sale in a shop? Leave the seat height jacked to the moon. Test rides? Availability of the small parts for the seat mast when the more volatile bike companies get on the bandwagon. They are light, new and probably prone to something they haven't figured out yet.

I was also thinking about those guys/gals that push your buttons when looking at bikes on the sales floor and never breaking out the wallet. "I like the bike, but before I spend the cash can you set it up for me?"

I see it on a custom or special order job for a keeper, but not something on the sales floor.

My client bought this bike without a test ride, the shop would not cut the seat mast for her if she did not commit to the purchase. So these bikes will be hard to sell off the floor. She plans to travel to distant places with this bike, I did not want to tell her of the difficulty in packing this bike with that mast. And lastly all bikes get sold used, none are keepers for life except a small rare bunch. The cut mast like a cut steerer poses some buying questions like what's your pedal to seat rail measurement? When did anybody ever ask this question before.

You are RIGHT on your post. I would have no issues buying a seat mast bike cause I think I am sure about my measurements BUT I will not suggest it for a entry level rider or for that matter a rider still getting fit on a bike.

[mike p]

I'm not sure what the big deal is. To me ISP is just another option. I think they look cool. Do they do anything other than coolness factor? I don't have enough experience to be able to say. But when did we start buying bikes that were 100% functional? Why aren't people complaining about decroative lugs, internal brake routing, terraplane seat stays along with many other nonfunctional things we adorn our bikes with? Very few builders have 100% functional bikes and nothing wrong with that, this is still the USA were alowed to build and ride what we want and not just what we need.

Mike

[zap]

Isp makes more sense that many custom frames I've seen.

[Lifelover]

I'm not sure what the big deal is. To me ISP is just another option. I think they look cool. Do they do anything other than coolness factor? I don't have enough experience to be able to say. But when did we start buying bikes that were 100% functional? Why aren't people complaining about decroative lugs, internal brake routing, terraplane seat stays along with many other nonfunctional things we adorn our bikes with? Very few builders have 100% functional bikes and nothing wrong with that, this is still the USA were alowed to build and ride what we want and not just what we need.

Mike


For the most part I agree with you. For all of us non pro riders, looks maybe the most important thing about our bikes and there is nothing wrong with that.

However, seat mast are slightly different than all the stuff you mentioned. While decorative lugs, internal brake routing and terraplane seat stays* may not add anything as far as function go, they don't distract from function. Seat mast do. A seat mast is not as functional as a seat post.


*I suspect terraplane seat stays make a small difference but we will leave that for DK.

[Ozz]

I've never had anyone ever tell me the benefit of the system. Looking cool is cool but what does it do?

Dave
no more cracked carbon seatposts?

[peanutgallery]

My client bought this bike without a test ride, the shop would not cut the seat mast for her if she did not commit to the purchase. So these bikes will be hard to sell off the floor. She plans to travel to distant places with this bike, I did not want to tell her of the difficulty in packing this bike with that mast. And lastly all bikes get sold used, none are keepers for life except a small rare bunch. The cut mast like a cut steerer poses some buying questions like what's your pedal to seat rail measurement? When did anybody ever ask this question before.

You are RIGHT on your post. I would have no issues buying a seat mast bike cause I think I am sure about my measurements BUT I will not suggest it for a entry level rider or for that matter a rider still getting fit on a bike.

Wow, talk about sales pressure, that'll give the customer warm fuzzies. Tough on the retailer, too. Difficult to remain customer friendly and not get hung with inventory that has an even narrower spectrum of fit.

I would be hesitant not to buy but to cut, just because I wanted to get it right. Measure twice cut once, I am sure there will be a rash of errors available in the classifieds, eventually.

I guess I should clarify. Among us addicts a keeper is something we plan to ride like twice, right? Thanks for the example

[Ray]

I'm not sure what the big deal is. To me ISP is just another option. I think they look cool. Do they do anything other than coolness factor? I don't have enough experience to be able to say. But when did we start buying bikes that were 100% functional? Why aren't people complaining about decroative lugs, internal brake routing, terraplane seat stays along with many other nonfunctional things we adorn our bikes with? Very few builders have 100% functional bikes and nothing wrong with that, this is still the USA were alowed to build and ride what we want and not just what we need.

Mike
Its not about 100% functional, its about not adding something DYSfunctional. Which a seat mast has, at least, the strong potential to be. Decorative lugs, internal cable routing, and terraplane stays may not add function (although I think you'd get a pretty solid argument about that on the terraplane stays), but they don't in any way impede the function of the bike. A seatmast, if not built for someone who a) has their position DIALED and can be sure they won't change it for many years, if ever, and b) WILL NOT sell the bike, at least not to someone who isn't basically the same size, could be quite dysfunctional.

Maybe they add a bit of stiffness and arguably some function as well. I doubt its anything I could detect but if someone wants one, good enough. I only fear the day when its hard to find a bike withOUT one, which I think will be a drag. But I'm a luddite. Even though I'm fine with threadless headsets, I had pretty much the same reaction when they came around - I just didn't want to see the quill stem made obsolete. It has become all but obsolete and I think that's too bad. But, if worse comes to worse, you can always buy a new fork if the steerer on the one you have has been cut too short. But a mis-cut seatmast would require you to buy a whole new frame, which is yet another level of magnitude in what I'd consider a drag.

-Ray

[David Kirk]

But when did we start buying bikes that were 100% functional? Why aren't people complaining about decroative lugs, internal brake routing, terraplane seat stays along with many other nonfunctional things we adorn our bikes with?

Mike

I'm sure no offense was meant by this but I take exception to the statement that the Terraplane stays are non-functional. I offer them purely for their function. Carved lugs and the such are purely aesthetic but the Terraplane stays have a function and as anyone who has ridden one would attest they perform their function well. I fully respect your right to disagree but unless you've ridden one you wouldn't know. Ask openly the owners and see what they say.

FWIW I think the seat mast thing does perform a function. It makes the connection of the saddle to the frame stiffer. This may or may not make the bike feel better..... I think it depends on the actual design. I think if a stiffer connection of the post to the frame is desirable then I think the better way to handle it would be using a seat tube of a large diameter to allow a larger diameter seatpost. This would make things stiffer without the downside of the hard to pack fame with limited adjustability.

I don't see the seat mast thing as being a bad thing at all. But I think the benefit is to the manufacturer and not the rider. It's easier to make a moulded frame if you move the seat clamp and the stress involved their away from the seat cluster. I think we'll see the seat mast thing go the way of the integrated headset. It will be out there but it will be just one of the options.

Time to get out of the house for me. Have a good Sunday.

dave

[alancw3]

it seems to me that with the popularity of compact carbon fiber frames that the integrated seat mast was a way for the manufacturers to strengthen and stiffen that area of the frame. with a compact frame you have longer seatposts with additional leverage on the seatpost binder system and seatpost itself. this stress area is probably more significant for a pro racer than a recreational rider. with all the wanabe racers i think you will see more seat mast systems not less particularly on top end bikes. i do see a functionality there. i don't see them as all that cool looking though. and yes i would like to try one.

finally what would concern me most is the resale factor. seems like you may have fewer people to potentially sell the bike to down the line. again just my $.02.

[false_Aest]

I only fear the day when its hard to find a bike withOUT one, which I think will be a drag.
-Ray

Since the advent of mp3 players I no longer have to strap my record player on my back when I want to go for a ride and listen to music.

Oddly, I can still buy vinyl and needles for my record player.

Even more strange is that I saw a record player for sale at Best Buy.

[Smiley]

Since the advent of mp3 players I no longer have to strap my record player on my back when I want to go for a ride and listen to music.

.


That's funny :)

[Ray]

Since the advent of mp3 players I no longer have to strap my record player on my back when I want to go for a ride and listen to music.

Oddly, I can still buy vinyl and needles for my record player.

Even more strange is that I saw a record player for sale at Best Buy.
Yeah, but with the mp3 player, you don't get that warm vinyl SOUND when you're out listening to music on a ride. :cool:

Point taken. I'm not against new stuff - I like more of it than not. And I don't love all that much old stuff. But SOME old stuff was too good to become, if not quite extinct, at least marginalized. Lots of, if not most, new stuff is pretty cool and lots of it stands the test of time until something even better comes along. I see seatmasts as something with a small potential upside for a small percentage of riders that's becoming so fashionable that it may marginalize a design that's far more useful to most of us. That's all.

-Ray

[avalonracing]

I agree.

Yay! We finally agree on something! :beer:

[mike p]

Dave, no disrespect or offense intended at all. Forgive my ignorance as I haven't ridden terraplane stays and assumed they were there for aesthetic reasons. I should have just said curved seatstays or curved chainstays you see on many different bikes ( I'm sure most of those manufactures would argue that they serve a purpose). My point was that every part on a bike dosen't have to be 100% functional, even on a race bike.

Mike


I'm sure no offense was meant by this but I take exception to the statement that the Terraplane stays are non-functional. I offer them purely for their function. Carved lugs and the such are purely aesthetic but the Terraplane stays have a function and as anyone who has ridden one would attest they perform their function well. I fully respect your right to disagree but unless you've ridden one you wouldn't know. Ask openly the owners and see what they say.

FWIW I think the seat mast thing does perform a function. It makes the connection of the saddle to the frame stiffer. This may or may not make the bike feel better..... I think it depends on the actual design. I think if a stiffer connection of the post to the frame is desirable then I think the better way to handle it would be using a seat tube of a large diameter to allow a larger diameter seatpost. This would make things stiffer without the downside of the hard to pack fame with limited adjustability.

I don't see the seat mast thing as being a bad thing at all. But I think the benefit is to the manufacturer and not the rider. It's easier to make a moulded frame if you move the seat clamp and the stress involved their away from the seat cluster. I think we'll see the seat mast thing go the way of the integrated headset. It will be out there but it will be just one of the options.

Time to get out of the house for me. Have a good Sunday.

dave

[Ray]

Yay! We finally agree on something! :beer:
I had a forum and PM exchange with Adam recently that was 100% friendly, helpful, and productive. Not a pedal was turned in anger. I barely knew how to act. :cool:

We need another political thread around here dammit! Things are just getting too damn friendly and cozy. But you guys have it - I'm not in the mood.

-Ray

[goonster]

IIRC, there was once a custom aluminum woman's bike from the Golden Age featured in the pages of BQ. The saddle clamp was welded directly to the seatpost, with zero vertical adjustment possible. So the idea has been around, and may make sense if worked out between a customer and builder.

For production bikes sold in stores . . . I can see how it gets problematic.

edit: I believe this is the bike. Amazing.

http://www.vintagebicyclepress.com/images/barrafull4.jpg

[blschaefer1]

I see both sides of this debate.

I have a Look 595, best carbon frame I've ever owned, and I happen to think the elastomers used in the e-post contribute to a very comfortable ride. This is the key advantage for me.

Cut to your individual minimum height, and you can adjust up.

Big downside - resale.

[fierte_poser]

I still don't get the argument that a stiffer seat cluser is a real benefit to a particular frame. I am open to explanations on how the torque/forces applied at the pedals would cause the seat cluster to go all wonky...and how the ISP thing solves that problem...anyone?

Further, one wouldn't need to extend the seat tube all the way to the saddle to gain the [supposedly required] stiffness at the seat cluster, correct? Wouldn't a one or two inch extension above the seat cluster achieve the same thing? Or is the argument: a bit longer seat tube is better, so a hugely longer seat tube must be best!

I guess now that frame deflection at the BB has been solved, its now time to direct our attention to deflection at the seat cluster? :cool:

[David Kirk]

Dave, no disrespect or offense intended at all. Forgive my ignorance as I haven't ridden terraplane stays and assumed they were there for aesthetic reasons. I should have just said curved seatstays or curved chainstays you see on many different bikes ( I'm sure most of those manufactures would argue that they serve a purpose). My point was that every part on a bike dosen't have to be 100% functional, even on a race bike.

Mike

No problem. No offense taken.

be well.

Dave

[sspielman]

A properly cut ISP makes a bike look like the builder/rider knew what they were doing. If you are an inexperienced rider-the sort that doesn't have his equipment sorted out.....or changes all sorts of adjustments frequently, and ISP is probably not for you.

[sg8357]

For the last several years Cycling+ has been explaining that the seat pin helps improve the ride quality of compact frames. So if you build a compact frame with an ISP where do you get your ride tuning ?

I predict Calfee will soon figure out how to extend an ISP for a nominal fee.

How big an ISP frame can you fit in a Trico case ?, maybe an S&S ISP
coupler for travel bikes ?

Silly Mode off.

[Sacha White]

FWIW, I designed the Speedvagen Cross bikes with an integrated seatmast because I wanted to get rid of all of excess brake hardware, brazeons etc. in the area, and run the cable straight through the seat tube.

I think this is a genuine improvement for a Cross racing machine.

The result is that the Speedvagen Cross frames are lighter (by 1/3 lb.) than a non-isp frames of the same tubing. Also the braking is smoother, stiffer and lower maintenance than a standard setup. The Seatmast and what it allows us to do with the design is one of the main reasons for these very real benefits.

"How about the road frame" you ask? Mostly cause it's hot and is visually consistent with our Cross bikes (although their owners talk about feeling more connected to the road...).

I agree with others here that a bike like this is not for a rider who is still figuring out what they need in a bike. Things like their fit, what pedal system they like and what saddle they like. In my experience, most folks who have solid time in on the bike have worked these details out.

Cheers :beer:

-Sacha

[RPS]

I still don't get the argument that a stiffer seat cluser is a real benefit to a particular frame. I am open to explanations on how the torque/forces applied at the pedals would cause the seat cluster to go all wonky...and how the ISP thing solves that problem...anyone?I expect they are referring to forces exerted by the rider at the saddle, not at the pedals. From that angle it’s easy to see a potential to save a little weight by eliminating a joint in a higher-stress area and replacing it with a straight tube.

IMO for this stiffness to be a positive change in the ride-versus-performance compromise it would have to support the saddle stiffer in the side-to-side direction and less stiff in the front-to-back direction (i.e. – the latter like compact frames). Not sure how effective builders would be at actually accomplishing that, and even if they do, the difference would have to be quite small.
Further, one wouldn't need to extend the seat tube all the way to the saddle to gain the [supposedly required] stiffness at the seat cluster, correct?Too logical. And too different to be accepted. ;)

[saab2000]

LBS told me that for carbon frames, it gives the builder more control over how the bike feels in regards to stiffness or compliance.



Did the LBS dude have grommets in his ear and lip too? And the oh-so-hip colored tats?

[goonster]

If the LBS dude were forbidden from using the words "stiffness" and "compliance", would he speak at all? :confused:

[Charles M]

Did the LBS dude have grommets in his ear and lip too? And the oh-so-hip colored tats?

I know a couple folks that fit that bill that know a thing or two about bikes...




FWIW, making generalizations about seat mast tech are about as usefull as moct other generalizations.

There are a couple of designs that consider a couple of differences in using the form and a couple that don't.

[cody.wms]

If the LBS dude were forbidden from using the words "stiffness" and "compliance", would he speak at all? :confused:


He could always talk about "technology"

[K Bedford]

Seat mast, to do or no which way do I go. I've stated many times, although not necessarily on this forum that on my frames I'll always try to honor the customers wishes of what they want to do with their frame short of making structural or functional compromises or doing something so aesthetically hideous that I wouldn't want my name on it.
I reserve the right to make the judgment on these things and because I have my own opinions not everybody out there will agree with what decide and I'll live with that.
Concerning this specific subject, do I think there is any distinct performance advantage to a seat mast? No.
Do I think there is any great performance or structural disadvantage? No.
Do I think there is a distinct aesthetic difference? Yes.
Is the aesthetic difference such that I wouldn't build it and put my name on it? No.
Do I think a frame with a seat mast will have a slightly different ride feel than the same frame built for and equipped with a traditional seat post?
Probably, but so will the conventional setup simply by changing models, manufacturers and or materials of seat post.
Ok, so maybe this would be an advantage to a conventional set up but there's any number of other things that can be changed on a given bike that will make far more dramatic differences in feel and performance that the matter of seat mast or no in these respects is relatively insignificant.
Concerning adjustment range of the seat mast system, a customer who is considering this should have well established position and preferences in saddles because the adjustment range is admittedly narrower than a conventional set up.
If a custom built frame requires more that 3cm +/- of adjustment to dial the rider then the fit is most likely wrong unless a wholesale saddle change is made from their original fit.
In my opinion there's nothing wrong with doing something purely for aesthetic reasons as long as it doesn't involve the couple of compromises I stated at the beginning of my reply.
If you can have a situation where an aesthetic change results in a performance enhancement or vice versa as in the case of Dave's Terraplane stays, so much the better.

[Louis]

Question for the builders who do use ISPs / ISMs:

I assume that because the bending moments reacted at the ST / TT / SS joint are significantly different if you have an ISP instead of a "regular" seatpost you can't just extend a ST up and put whatever needs to go on at the top. I would guess that if one did try that it would result in significantly higher stresses at the ST / TT / SS joint and possibly result in failure of the ISP at the joint. If that is true, do you simply use a different butting or ply layup scheme for the ST? Or can existing ST thickness designs handle the ISP?

Louis

[Sacha White]

Question for the builders who do use ISPs / ISMs:

I assume that because the bending moments reacted at the ST / TT / SS joint are significantly different if you have an ISP instead of a "regular" seatpost you can't just extend a ST up and put whatever needs to go on at the top. I would guess that if one did try that it would result in significantly higher stresses at the ST / TT / SS joint and possibly result in failure of the ISP at the joint. If that is true, do you simply use a different butting or ply layup scheme for the ST? Or can existing ST thickness designs handle the ISP?

Louis

The area of the seat tube where the toptube and seatstays join it has to be thicker than a traditional seat tube. Ours is butted to 1.2mm in that area, whereas a standard seat tube is .6mm.

[Louis]

The area of the seat tube where the toptube and seatstays join it has to be thicker than a traditional seat tube. Ours is butted to 1.2mm in that area, whereas a standard seat tube is .6mm.

Thanks Sacha. With no beefy seatpost in there, I figured that had to be the case.

Louis

[Sacha White]

:beer:

[RPS]

Thanks Sacha. With no beefy seatpost in there, I figured that had to be the case.

LouisLouis, are you saying "beefy" seatposts are stronger than seattubes? If so, in what materials? :confused:

I must not be following the gist of your question regarding bending moments.

[alancw3]

i am not a frame builder but i cannot help but think that there is a significant increase in structrual integrity IN A COMPACT CARBON FIBER FRAME using an integrated seat mast system. eliminating the seatpost and the binder mechanism just seems so much stronger albeit again i am only talking carbon fiber compact frames. do i think they are as aesthetically pleasing to the eye? absolutely not, but hey i am a traditionalist that doesn't think that extended head tubes add to the beauty of a bike either. go figure!

[Tobias]

The area of the seat tube where the toptube and seatstays join it has to be thicker than a traditional seat tube. Ours is butted to 1.2mm in that area, whereas a standard seat tube is .6mm.Why does the elimination of the seat post require a thicker seat tube, and how can a thicker seat tube lead to a much lighter frame as normally claimed for integrated seat posts?

I can see how the seat stays could crush a seat tube if made of very thin material like a Coke can, but for a regular steel or titanium frame I can't follow the need for extra thickness. I'm sure you know and hopefully will share with us.

[I Want Sachs?]

Does seat mast allow rotational adjustment to the saddle? I have a slightly rotated anatomy, and my saddle is not 100% straight aligned for best comfort. I would need about 2-3 degrees of rotation. Does seat mast allow that? Thanks.

[Smiley]

Does seat mast allow rotational adjustment to the saddle? I have a slightly rotated anatomy, and my saddle is not 100% straight aligned for best comfort. I would need about 2-3 degrees of rotation. Does seat mast allow that? Thanks.
NO, at least not the ones I have seen so far :)

[David Kirk]

Why does the elimination of the seat post require a thicker seat tube, and how can a thicker seat tube lead to a much lighter frame as normally claimed for integrated seat posts?

I can see how the seat stays could crush a seat tube if made of very thin material like a Coke can, but for a regular steel or titanium frame I can't follow the need for extra thickness. I'm sure you know and hopefully will share with us.

I can't speak for Mr. White but I believe the issue is one of bending. There is a large bending load with the cantilevered beam that is the seat post or ISP. Putting a large butt on the saddle and bouncing it up and down tries to bend whatever is holding it up to the rear and most all of that force is concentrated at the top of the top tube/seatstay juncture. If one were to use a thin tube there I'd be nervous about long term reliability with a failure of the thin tube. With a traditional seat post design the post itself takes most of the bending load. With an ISP the load is on the seat tube and not the post.

One of the other things to consider is the fact that the seat stays are trying to push their way through the back of the seat tube whenever you hit a bump. With a traditional seat post design the seat tube is prevented from being damaged by the support of the seat post inside. The seat post acts as an internal reinforcement to the seat tube. With an ISP the seat tube needs to have a heavy enough wall to provide it's own reinforcement since there is nothing inside to provide help.

I think things could be kept reasonably light with an ISP if the seat tube had a heavier wall where the top tube and stays meet it and then get thin again when the tube gets closer to the saddle. But still it's hard to make it lighter than a traditional frame with a alloy or carbon post since you are in effect getting rid of some seat post (light weight alloy or carbon) and replacing it with some seat tube (heavier steel).

I suspect the weight loss seen in the SV cross bikes comes as much from the elimination of a brake cable hanger bridge, a spilt cable guide and some brake cable housing as it does from the mast itself. Do I have this right Sacha?

dave

[sspielman]

Does seat mast allow rotational adjustment to the saddle? I have a slightly rotated anatomy, and my saddle is not 100% straight aligned for best comfort. I would need about 2-3 degrees of rotation. Does seat mast allow that? Thanks.

I have two bikes utilising ISP's with completely different designs....one Time and one Carrera...You could mount the seat sideways on the Time....and the system on the Carrera would allow for about 15 deg of angle. (The Carrera comments would also apply to DeRosa, Guerciotti and others that use the same system)....

[Sacha White]

Does seat mast allow rotational adjustment to the saddle? I have a slightly rotated anatomy, and my saddle is not 100% straight aligned for best comfort. I would need about 2-3 degrees of rotation. Does seat mast allow that? Thanks.

I guess some do and some don't. That interface on Speedvagen is round and doesn't index like a shaped (aero?) junction would.

[flydhest]

Putting a large butt on the saddle and bouncing it up and down

I had already put my nerdy, poseur, wish-I-understood framebuilding hat on and thought "but I thought it was butted down where it hits the top tube, not up by the saddle."

Dave, so as not to hurt my pea brain again, any chance I could get you to use the word "fanny" and reserve "butt" for different thickness of tubing.

:D

[David Kirk]

I had already put my nerdy, poseur, wish-I-understood framebuilding hat on and thought "but I thought it was butted down where it hits the top tube, not up by the saddle."

Dave, so as not to hurt my pea brain again, any chance I could get you to use the word "fanny" and reserve "butt" for different thickness of tubing.

:D

When I try to type fanny it hurt so lets say "arse".

dave

[Sacha White]

I can't speak for Mr. White but I believe the issue is one of bending. There is a large bending load with the cantilevered beam that is the seat post or ISP. Putting a large butt on the saddle and bouncing it up and down tries to bend whatever is holding it up to the rear and most all of that force is concentrated at the top of the top tube/seatstay juncture. If one were to use a thin tube there I'd be nervous about long term reliability with a failure of the thin tube. With a traditional seat post design the post itself takes most of the bending load. With an ISP the load is on the seat tube and not the post.

One of the other things to consider is the fact that the seat stays are trying to push their way through the back of the seat tube whenever you hit a bump. With a traditional seat post design the seat tube is prevented from being damaged by the support of the seat post inside. The seat post acts as an internal reinforcement to the seat tube. With an ISP the seat tube needs to have a heavy enough wall to provide it's own reinforcement since there is nothing inside to provide help.dave

agreed

I think things could be kept reasonably light with an ISP if the seat tube had a heavier wall where the top tube and stays meet it and then get thin again when the tube gets closer to the saddle. But still it's hard to make it lighter than a traditional frame with a alloy or carbon post since you are in effect getting rid of some seat post (light weight alloy or carbon) and replacing it with some seat tube (heavier steel).dave

Our setup is exactly as you describe. Thin up to the point where the tt and ss join. It is beefed up there and then tapers back down to a thin wall up to the top. It's a bit lighter than a standard setup with seatpost clamp, etc.

I suspect the weight loss seen in the SV cross bikes comes as much from the elimination of a brake cable hanger bridge, a spilt cable guide and some brake cable housing as it does from the mast itself. Do I have this right Sacha?

dave

Yep, you are right. Most of the weight savings comes from what the ISP allows us to do with the other design elements, not the ISP itself. We wouldn't be able to integrate the brakes to the extent that we have without the isp though, making it a necessity for this particular bike and (imo) giving it a distinct performance advantage.

-Sacha

[jeffg]

My only issues with an ISP are that any one I have seen would not fit in my bike cases, and I may eventually need to switch saddles if I can't get replacement SSM Eras, so then I may end up with a useless frame.

My bikes travel with me, so the first one is deal killer for now

[EDS]

My only issues with an ISP are that any one I have seen would not fit in my bike cases, and I may eventually need to switch saddles if I can't get replacement SSM Eras, so then I may end up with a useless frame.

My bikes travel with me, so the first one is deal killer for now

If you only have one bike I could see this being a deal breaker, but if you have more then one, well . . .

[sg8357]

If you are really worried about seatmast stiffness, you could try a larger version of the Moulton NS pylon. Price ?? if you have to ask...

Scott G.

[David Kirk]

If you are really worried about seatmast stiffness, you could try a larger version of the Moulton NS pylon. Price ?? if you have to ask...

Scott G.

Space frames support the planet.

dave

[K Bedford]

Dave's got it right.

[geoffm]

I am on my first ISP this season. I used to think the same thing about the faults of ISP, then I rode it.

The bike I am on was Andreas Klier's Giant TCR Advanced SL from last season. I am informed that the bike is the third of four prototypes tested by Team Columbia before Giant arrived at the production version.

The frameset that I have is a perfect example of why the ISP design might make good sense. I am informed that the Team Columbia race bike has considerably more carbon layups in the headtube junction with the downtube and in the bottom bracket/chainstay cluster than the production bike, yet the bike 'rides' quite 'softly'. I have been told that this ride characteristic was 'tuned-in' to the bike through the combination of the shape and carbon layups in the ISP mast and the ISP/seatcluster junction and would not be possible with a conventional post design.

Among the other crazy-stiff bikes in my ex-pro 'stable' are Nibali's SuperSix and Grivko's EP (also featuring extra carbon layups as compared to the production bike). I think the Giant is stiffer in the headtube and slightly stiffer bottom bracket, in the case of the EP, and the reverse, in the case of the Cannondale (caveat: I am 59kgs and produce 1,200 watts in a sprint, so I am no big-gear masher). The Giant, however, is much 'softer' feeling in the saddle, no small thing after 4 or 5 hours. I attribute this to the ISP design.

[RPS]

I can't speak for Mr. White but I believe the issue is one of bending. There is a large bending load with the cantilevered beam that is the seat post or ISP. Putting a large butt on the saddle and bouncing it up and down tries to bend whatever is holding it up to the rear and most all of that force is concentrated at the top of the top tube/seatstay juncture. If one were to use a thin tube there I'd be nervous about long term reliability with a failure of the thin tube. With a traditional seat post design the post itself takes most of the bending load. With an ISP the load is on the seat tube and not the post.The picture below is an example of what you described. In fairness to the builder (whoever it was) nothing is abuse proof, and in this case the saddle may have been supported so high that even if the seattube extension had been replaced with a conventional but much longer seat post, failure may have occurred anyway. If not the frame maybe the seat post.

I personally don’t get the idea of relying on an “exaggerated” compact layout to soften the ride (whether it necessitates a mast or simply an extremely long seat post). Either way it creates very high stresses for what it accomplishes. Very inefficient use of material IMHO. At some point they’d be better off building a beam bike. :rolleyes:

[Climb01742]

I am on my first ISP this season. I used to think the same thing about the faults of ISP, then I rode it.

The bike I am on was Andreas Klier's Giant TCR Advanced SL from last season. I am informed that the bike is the third of four prototypes tested by Team Columbia before Giant arrived at the production version.

The frameset that I have is a perfect example of why the ISP design might make good sense. I am informed that the Team Columbia race bike has considerably more carbon layups in the headtube junction with the downtube and in the bottom bracket/chainstay cluster than the production bike, yet the bike 'rides' quite 'softly'. I have been told that this ride characteristic was 'tuned-in' to the bike through the combination of the shape and carbon layups in the ISP mast and the ISP/seatcluster junction and would not be possible with a conventional post design.

Among the other crazy-stiff bikes in my ex-pro 'stable' are Nibali's SuperSix and Grivko's EP (also featuring extra carbon layups as compared to the production bike). I think the Giant is stiffer in the headtube and slightly stiffer bottom bracket, in the case of the EP, and the reverse, in the case of the Cannondale (caveat: I am 59kgs and produce 1,200 watts in a sprint, so I am no big-gear masher). The Giant, however, is much 'softer' feeling in the saddle, no small thing after 4 or 5 hours. I attribute this to the ISP design.

thanks for contributing your experiences. but now you gotta spill the beans. :D how the heck did you get a pipeline to pro bikes????????

[nahtnoj]

The picture below is an example of what you described. In fairness to the builder (whoever it was) nothing is abuse proof, and in this case the saddle may have been supported so high that even if the seattube extension had been replaced with a conventional but much longer seat post, failure may have occurred anyway. If not the frame maybe the seat post.



The "builder" of that bike is Gary Fisher. It is a 29er frame. They did this to improve standover clearance but didn't spec a long enough seatpost to get past the tube junction. Its not a seat mast per se in the sense they are being discussed in this thread, just an excellent example of bad design.

[David Kirk]

The "builder" of that bike is Gary Fisher. It is a 29er frame. They did this to improve standover clearance but didn't spec a long enough seatpost to get past the tube junction. Its not a seat mast per se in the sense they are being discussed in this thread, just an excellent example of bad design.

Funny isn't it? They could have made the seat tube 2" shorter and used their regular clamp and they would have saved a bit on materials, saved a very small amount of weight, made reaming the seat tube easier and kept the thing from breaking. With any of these set ups there needs to be enough post buried in the frame so give everything the proper support.

Dave

[nahtnoj]

Funny isn't it? They could have made the seat tube 2" shorter and used their regular clamp and they would have saved a bit on materials, saved a very small amount of weight, made reaming the seat tube easier and kept the thing from breaking. With any of these set ups there needs to be enough post buried in the frame so give everything the proper support.

Dave

I'm no framebuilder, but yes!

Or they could have gone the Turner route and added a small brace to the TT/ST junction and moved the CS junction back to the normal level. Would have accomplished the increased standover, but I'm sure the actuaries nixed the two extra passes by the robot welder.

[shinomaster]

I've never had anyone ever tell me the benefit of the system. Looking cool is cool but what does it do?

Dave


I hear it feels different.

[Lifelover]

I hear it feels different.

"An integrated seat mast is employed to allow a more direct connection between the rider and the bicycle especially during hard seated cornering where a rider puts extra force into the seat tube and seat post assembly."

[djg]

When I try to type fanny it hurt so lets say "arse".

dave

Dave, a tuches, by any other name . . .

[Ray]

I was just checking out some of the info on the Jerk's new frames and the seatmast "cap" - the thing that mounts to the top and clamps the saddle rails - has 4 cm of adjustability. That increases my comfort level. I thought you really had to nail your position and changing saddles or pedals could really mess you up. But with nearly two inches of vertical range to play with, that should be able to accommodate pretty much any change an individual rider would make and would cover a decent amount of re-sale too.

I'm still not sure they matter much and I'm pretty damn sure they wouldn't matter to me, but the biggest downside I perceived now appears to be a much smaller downside than I thought.

-Ray

[RPS]

The "builder" of that bike is Gary Fisher. It is a 29er frame. They did this to improve standover clearance but didn't spec a long enough seatpost to get past the tube junction. Its not a seat mast per se in the sense they are being discussed in this thread, just an excellent example of bad design.If I had found a picture of a broken seat mast I’d have posted that instead. :)

Besides, the picture addressed two issues discussed previously in this thread. First, fierte_poser questioned why builders wouldn’t just extend the seat tube part way to the saddle but still maintain the adjustability of a conventional seat post. I think the amount of seat tube extension on the picture above is probably close to a possible middle ground; particularly if applied to a road bike.

Secondly, if a rider doesn’t insert a seat post far enough in the seat tube extension, stresses at the top tube joint will be comparable to that which are created by a mast (assuming everything else being equal since the bending moment is essentially the same). And added stresses at the point of failure were discussed extensively – including the need to reinforce the seat tube.

I agree that that much seat tube extension is questionable design. IMO when a builder provides what looks like about 3 inches of seat tube extension on a frame with lots of top-tube slope, they are asking for someone to use a shorter seat post that doesn’t penetrate beyond the top tube. Even if they specified otherwise, someone is going to screw up and end up breaking something. On a road bike with a level or slightly sloping top tube I don’t think the amount of bending moment would be a major problem, but obviously on a MTB which is subjected to greater impact loads it is -- especially when the saddle is cantilevered a foot above the main triangle.

[zap]

Ray, you can cut down Times VXRS et al seatmast down to traditional height and adjust a seatpost as normal.

Seat mast designed kit have more panache than most customs here and higher resale value to boot.

I'm working on :) and before you know it, not only will he be riding carbon, but he'll be riding serotta's new seatmast equiped frameset. :banana:

[Smiley]

Ray, you can cut down Times VXRS et al seatmast down to traditional height and adjust a seatpost as normal.

Seat mast designed kit have more panache than most customs here and higher resale value to boot.

I'm working on :) and before you know it, not only will he be riding carbon, but he'll be riding serotta's new seatmast equiped frameset. :banana:


:) maybe riding the HSG carbone in not the distant future but sans the Mast

[zap]

:) maybe riding the HSG carbone in not the distant future but sans the Mast

One step at a time. :banana: