ST pivot bearing play [Archive] - The Paceline Forum

Pete Serotta

05-25-2011, 10:47 AM

CAN PROVIDE ASSISTANCE. LABOR OF THE PRICES I HAVE READ HERE ARE NOT OUT OF RANGE. LBS HAVE PEOPLE AND STORE TO PAY ON A MONTHLY BASIS. THERE IS A TOOL THAT IS USED TO REPLACE, GET THEM TO EXPLAIN HOW TO LUBE OCCASIONALLY. I PERSONALLY HAVE NEVER HAD A DEFECT EVEN ON MY TRAVEL BIKE.

TELL THEM PETE GAVE THEIR NAME.

Apologies if this has been answered; my searches did not find one.

While tracking down an annoying rattle that developed on my ride tonight, I detected a tiny bit of play in my Ottrott ST's pivot bearings. The play is side-to-side (pulling the seatstays outward), slightly more on the drive side. I detect no play vertically, and this wasn't the source of the rattle.

So, is this amount of horizontal play normal, or is it time for a bearing rebuild?

Ahneida Ride

05-25-2011, 10:52 AM

The big expense for the shop is the special tool.

It is expensive and how many times will it be used ?

Brian Smith

05-26-2011, 08:32 PM

The big expense for the shop is the special tool.

It is expensive and how many times will it be used ?

It probably should get used more times than a hub toolset for expensive hubs gets used. It is comparatively not expensive, but unfortunately only works about as well, and no better. A shop could make back the expense of the tool relatively quickly, as they can and do with suspension servicing tools.

It's a job that ought to be done by a very good mechanic or by the factory.
A majority of refinished frames receive this treatment as part of the service.

mjbrekke

05-27-2011, 08:50 PM

I talked to Steve at Serotta (thanks, Pete). He said the symptoms are exactly those of worn bearings so it's time to replace them. The bearings are designed as a wear item like a chain, and he's seen a similar YMMV-like range of miles depending on where and how one rides.

Serotta no longer makes and sells the required tool, but fortunately my LBS (Flanders Bros) says they have it. They don't have the bearings, though.

Steve recommended that I check Boca Bearings (www.bocabearings.com) for the bearings--13mm OD, 6mm ID, and 5mm width, stainless steel or ceramic, with stainless steel seals. He thought they should cost $15-30 per set.

Boca's website has 36 bearings that size ranging from $3.75 to $99.95 per bearing. For $9.95 there is a stainless/ceramic for bicycle applications. Only problem is the options. First, grease or no grease. Second, there are two types, normal (CN) and C3, where they have different internal clearances. Which is correct depends on the application and whether it is a press fit on both outer and inner surfaces and the expected operating temperature.

Making progress, but it looks like another call to Steve on Tuesday, then an order with Boca. Stay tuned...

BlackTiBob

05-28-2011, 08:18 AM

Thanks. Please keep us informed, like what are best/most appropriate options at what prices.

I'm in St.Paul if you need to look at set--I saved my old set.
Bob

Pete Serotta

05-28-2011, 02:48 PM

They are very helpful both Steve and Scott

And let me know if you can not get a bearing and a dealer I use can probably get it, if yours can not. PETE

I talked to Steve at Serotta (thanks, Pete). He said the symptoms are exactly those of worn bearings so it's time to replace them. The bearings are designed as a wear item like a chain, and he's seen a similar YMMV-like range of miles depending on where and how one rides.

Serotta no longer makes and sells the required tool, but fortunately my LBS (Flanders Bros) says they have it. They don't have the bearings, though.

Steve recommended that I check Boca Bearings (www.bocabearings.com) for the bearings--13mm OD, 6mm ID, and 5mm width, stainless steel or ceramic, with stainless steel seals. He thought they should cost $15-30 per set.

Boca's website has 36 bearings that size ranging from $3.75 to $99.95 per bearing. For $9.95 there is a stainless/ceramic for bicycle applications. Only problem is the options. First, grease or no grease. Second, there are two types, normal (CN) and C3, where they have different internal clearances. Which is correct depends on the application and whether it is a press fit on both outer and inner surfaces and the expected operating temperature.

Making progress, but it looks like another call to Steve on Tuesday, then an order with Boca. Stay tuned...

mjbrekke

05-31-2011, 10:47 PM

Bob, are your old bearings marked with any part numbers?

BlackTiBob

06-01-2011, 08:05 AM

I took them apart, bolt/nut/bearing.
No numbers on them, even when looking with magnifying glass.
Bummer

Bag has Serotta part #
SER19108398T

Pete Serotta

06-01-2011, 08:25 AM

It is sold as one item and that is why one part ##s. Putting a part # on each item buys Serotta or the customer any value.

Sorry.

PETE

I took them apart, bolt/nut/bearing.
No numbers on them, even when looking with magnifying glass.
Bummer

Bag has Serotta part #
SER19108398T

mjbrekke

06-14-2011, 09:57 PM

After talking again with Steve Fairchild at Serotta, I called Boca Bearings. They suggested bearing # SMR686C-YZZ #5 NB2. It's a greased stainless/ceramic hybrid with stainless seals, $15.95 each shipped. Even though there are other bearings that appear identical to me on their web site and this bearing is not specifically classified for bicycles, Boca quickly rejected the other model numbers I suggested. Once they arrive, I'll head over to Flanders Bros for installation. I'll let you know how it works out.

BlackTiBob

06-15-2011, 07:51 AM

thanks,
please do let us know how that works out and what Flanders charges to install.
If you have a chance, eyeball the special Serotta install tool, just curious what that bad boy looks like.

I'd order a couple sets if that works like the stock bearing.

Bob in St. Paul

palincss

06-15-2011, 02:53 PM

While tracking down an annoying rattle that developed on my ride tonight, I detected a tiny bit of play in my Ottrott ST's pivot bearings.

What is an Ottrott ST pivot bearing?

dave thompson

06-15-2011, 03:49 PM

What is an Ottrott ST pivot bearing?
From Serotta:
Seat Stay
The seat stay, often referred to simply as stay, connects the top of the seat tube to the rear dropouts that hold the rear wheel. Serotta has designed three different carbon seat stays for improved vertical compliance and vibration damping.

* Serotta Patented Carbon Fiber Stay and Pivot System
Proprietary curved ST carbon fiber seat stay, produced in the US, is joined to the dropouts by a bearing system that allows a small degree of vertical compliance in the rear end of the bike. This added compliance helps to keep the rear tire in contact with the ground during hard cornering and acceleration while also providing increased vibration damping.

FEATURED ON: Ottrott SE, Legend SE

* CS
Serotta Carbon Fiber Seat Stay w/ Fixed Boss
Proprietary curved carbon fiber seat stay, produced in the US to our exacting standards. Carbon fiber has superior damping qualities to other materials -- adding carbon to the rear end of a bike helps smooth out high frequency vibrations.

FEATURED ON: Ottrott GS, Coeur d'Acier SE, CXII Steel, Ottrott RC

mjbrekke

06-30-2011, 09:45 PM

I picked up my bike from Flanders tonight. It took a while because they recommend replacing the bolts and nuts, too, and they had to get them from Serotta. Looking at the old parts, I think the old nuts could have been used, but the bearings were definitely shot and the bolts had some significant wear. One bearing was much worse than the other, so that coincides with the greater play I observed on the drive side when I flexed the seatstays outward. I haven't ridden it yet, but the play is gone so I'm looking forward to an even better ride.

I didn't get a look at the tool involved. The mechanic described it as being like a gear puller. He said it was tricky to use because there isn't much surface on the seatstay for the tool to press against. My bearings came out without much trouble, but sometimes there has been enough moisture back there that it takes extra time.

Flanders charged $14.95 per nut/bolt set and $25 labor for a total $57.22 with tax. That makes the total cost with the Boca Bearings just under $90. According to Flanders, the bearings generally seem to last 8 years or so. $11 per year--I can live with that.

Kontact

06-30-2011, 11:47 PM

Caution whoever does the work not to lose the tiny internal washers - Serotta apparently doesn't have those either, and they aren't a standard part like a bearing.

Does anyone know why Serotta can't supply parts for a system it continues to sell? They do wear out and need replacement over time. I did two replacements last month, and the gorgeous Ottrott that arrived today has them.

oldpotatoe

07-01-2011, 07:50 AM

gone

07-01-2011, 09:04 AM

Does anyone know why Serotta can't supply parts for a system it continues to sell? They do wear out and need replacement over time.

I have to say I don't understand this either. Requiring your customers to dig around to find a replacement wear item that you still produce seems like very poor customer service to me. I have a Legend ST and even though I maintain the bearings and just had them replaced it makes me less than optimistic about the long term viability of the bike.

forrestw

07-01-2011, 02:16 PM

I had a look at mine this morning and when I find a few free hours I will measure it up and make a tool --- once done I will be glad to loan it to anyone sending an SASE. As far as the bearings go, I alway prefer to go to the local bearing house as they charge a lot less.

I have to say I don't understand this either. Requiring your customers to dig around to find a replacement wear item that you still produce seems like very poor customer service to me. I have a Legend ST and even though I maintain the bearings and just had them replaced it makes me less than optimistic about the long term viability of the bike.

mjbrekke

07-01-2011, 02:44 PM

Flanders didn't mention to me that they couldn't get parts from Serotta. They didn't give me any washers in bag of old parts, so maybe they used the old ones. I found it interesting that Serotta recommended that I go to Boca Bearings for the bearings, but they never said they didn't have them. Flanders replaces a lot of these, and they seem to be able to get what they need for them.

Now, the tool is another matter. Serotta told me that it is no longer made.

Pete Serotta

07-01-2011, 05:50 PM

Is this a used bike that you bought and then do not go to a dealer for it is not in your budget? And a dealer is there if you need one. Thanks Pete

Flanders didn't mention to me that they couldn't get parts from Serotta. They didn't give me any washers in bag of old parts, so maybe they used the old ones. I found it interesting that Serotta recommended that I go to Boca Bearings for the bearings, but they never said they didn't have them. Flanders replaces a lot of these, and they seem to be able to get what they need for them.

Now, the tool is another matter. Serotta told me that it is no longer made.

Kontact

07-01-2011, 07:05 PM

Is this a used bike that you bought and then do not go to a dealer for it is not in your budget? And a dealer is there if you need one. Thanks Pete
I work at a Serotta dealer. Do you know where we can get the washers?

Also, we've seen a lot of rust issues with the Boca bearings. Is there a stainless version and we're ordering the wrong part, or is that just wear and tear on these?

forrestw

07-09-2011, 07:53 AM

The bearing specified above in this thread is a hybrid w/ 440c stainless race/body parts and ceramic balls. Now 440c does still rust (some) but in this size I'd say they hybrid bearing is the best choice for the task at hand (straight-ceramic bearings are rated for 2/3 lower loading).

I have to wonder why Serotta is using a bearing with a steel dust shield, that's going to admit rain, grit etc into the bearing races.

Pete, you or anyone at Serotta care to comment on why replacing this bearing with one using a rubber seal would be a bad idea? (An otherwise identical ABEC-5 bearing with rubber seals is only a couple of $ more per part.)

Pete Serotta

07-09-2011, 10:35 AM

It probably should get used more times than a hub toolset for expensive hubs gets used. It is comparatively not expensive, but unfortunately only works about as well, and no better. A shop could make back the expense of the tool relatively quickly, as they can and do with suspension servicing tools.

It's a job that ought to be done by a very good mechanic or by the factory.
A majority of refinished frames receive this treatment as part of the service.

Thanks.....PETE

HenryA

07-09-2011, 07:13 PM

snipped........

Pete, you or anyone at Serotta care to comment on why replacing this bearing with one using a rubber seal would be a bad idea? (An otherwise identical ABEC-5 bearing with rubber seals is only a couple of $ more per part.)

I'm not at Serotta but I'd replace mine with a sealed bearing without hesitation. I also would not go overboard on specifying the bearing. This use does not call for anything special, IMO. If it stays clean and full of grease you're good to go for a long time.

For anyone in Tennessee or the Southeast U.S. this shop has the tools and experience to replace these bearings:

www.thebicyclefitter.com

.

Kontact

07-09-2011, 07:49 PM

Thanks.....PETE
I'm a very good mechanic who does these fairly often to the Serotta's we sell and service. Would you prefer to PM me information about the bearing and washers?

Not trying to be a pain here. I just thought I might be able to find more information than we've heard from the usual channels. We all thought the parts were gone because this system had been discontinued, but then that Ottrott showed up...

Pete Serotta

07-13-2011, 09:24 AM

- we always tout the benefits of the ST rear end as one of the
highlights of the Ottrott SE (and a major selling points) and have for
quite some time.
- We have had parts for these all along. There are some
ceramic/stainless hybrid bearings from Boca that are a bit more
expensive, but have better corrosion resistance than the standard
bearings. They are an upgrade per se.
- As Brian had stated in the thread,
these replacements need to be done when they wear out
- These are a wear item much like a cogset. One doesn't go to the
manufacturer of the frame when their cogs wears out.
- We (SEROTTA) believe in service and thus provide the bearings and parts,
but there are some aftermarket sources as well.
- The bearing replacement tool was made in house and we specifically asked
dealers to pre-order them as they are intricate and fairly expensive.
Several did, but some dealers did not, even though they need them.
- We can provide this service here for customers of dealers that do not
have the tool, and if it is once every 2 or 3 years should not pose to
big a problem.
- The largest issue with this system is that most people do
not realize, or were not told that this is a wear item that will require
service, so they do not keep an eye on it and then get frantic when it
needs to be replaced as most have realized after it is too late and the
bearings have played out.

Then someone posts on the forum and slings incorrect information about Serotta and the ST rear..... THis is why we have Dealers and the FORUM to help owners enjoy their Serotta bike.
__________________________________________________ _______________
Folks buy used SEROTTAs on the web and quite often do not know the prior maintenance nor do they particularly know the ST current condition. This is something that should be checked and not assume what the prior owner's maintenance was. Used is used and is the responsibility of buyer or seller.

SEROTTA is in the service business. They support the forum for it is a good communications vehicle. Additionally they support their products and even warranty defects to original owner.

ST/PIVOT requires maintenance just as other mechanicals need maintenance. This is not saying it is bad --

High end vehicles should have fluid in brakes replaced every 2 or 3 years also BUT many folks skip it because it costs $$. The "used" buyer than somewhere later ends up with repairs. (that also is not the mft fault) But they will be blamed :crap: :crap:

Know the maintenace required on your bike, no matter what brand. It also means checking for cracks or wear on things, including the frame. There are many pubs and online reference areas to learn from if a good dealer is not close by. If you are the original owner check with your dealer periodically and even check with us (or me - send me real name, not ID, or call Serotta with that info. We are here to help.

PETE

CNY rider

07-13-2011, 09:36 AM

Pete the thing about your cogset wearing out is that it is a commodity item and can be purchased at a hundred different places. The specs are well known and the cogsets are interchangeable.
If the St bearings have to be replaced intermittently then Serotta has to get the info out there, and should facilitate the process because it is their proprietary product.

Pete Serotta

07-13-2011, 09:37 AM

the team in SEROTTA (Steve, Brian among others). Send to me name and dealer and your email there and I will close the loop on it/

Pete@serotta.com

I'm a very good mechanic who does these fairly often to the Serotta's we sell and service. Would you prefer to PM me information about the bearing and washers?

Not trying to be a pain here. I just thought I might be able to find more information than we've heard from the usual channels. We all thought the parts were gone because this system had been discontinued, but then that Ottrott showed up...

SPOKE

03-20-2012, 08:37 PM

Can anyone tell me if there is a special socket required to hold the conical nut for the ST pivot? Maybe it's an external Torx socket?

93legendti

03-20-2012, 08:59 PM

Brian Smith

03-21-2012, 09:41 AM

Thanks Brian.
I still have the original bearings in my '07 Ottrott ST. Should I lube the bearings?

You could remove the bolt and nut, clean whatever has accumulated outside the shielding, then reinstall with medium strength removable threadlocker on the bolt, tightened to the proper specification for that thread size (we used 60 in-lb.)
There isn't a good way to lubricate that bearing without removing it, and upon removal, I'd instead recommend replacement, due to their standard industrial size and low cost.
If you can hold your dropout in a fixed location but move the seatstay boss outward from the dropout, then you have non-adjustable bearing play and they should be replaced.

93legendti

03-21-2012, 01:02 PM

You could remove the bolt and nut, clean whatever has accumulated outside the shielding, then reinstall with medium strength removable threadlocker on the bolt, tightened to the proper specification for that thread size (we used 60 in-lb.)
There isn't a good way to lubricate that bearing without removing it, and upon removal, I'd instead recommend replacement, due to their standard industrial size and low cost.
If you can hold your dropout in a fixed location but move the seatstay boss outward from the dropout, then you have non-adjustable bearing play and they should be replaced.
Ok, thanks. I'm pretty sure I have a replacement set of I bought from Serotta...

Dromen

05-21-2012, 04:47 PM

I rec'd this AM in an email from serotta. Is the 12pt hex socket the hard to find tool?

"The ST bearing should be checked during regular maintenance. The bearing itself should last a few years depending on use and environmental conditions. Use the same lube as on your chain to avoid corrosion from the elements. The pivot nut should be kept tight and torqued to 50 in/lbs using a 12pt hex socket."

A1A

05-22-2012, 08:28 AM

CNY rider

05-22-2012, 09:17 AM

Hi,

Can anyone happen to tell me if there is a shop in the Upstate New York area that can do the bearing replacement? I live in the Binghamton area and I'm pretty sure there is no shop here that can but how about Syracuse (go Orange!), Utica, Albany - Capital District?

Thanks!

Try Blue Sky in Saratoga.
Long time high volume Serotta dealer with quality mechanics.
Not sure if they still sell Serotta, but probably still have the tools.

Dromen

05-22-2012, 09:29 AM

Is the 12pt hex socket the "hard to find" tool?

Mr. LeBoyer sent me this email yesterday on ST bearing maintenance and i am confused as to what is so special about a 12pt hex socket. HELP.

5/21 email:
"The ST bearing should be checked during regular maintenance. The bearing itself should last a few years depending on use and environmental conditions. Use the same lube as on your chain to avoid corrosion from the elements. The pivot nut should be kept tight and torqued to 50 in/lbs using a 12pt hex socket."

Plum Hill

05-22-2012, 10:22 AM

I find the required maintenance interesting, as I have two ST-equipped bikes bought from two different dealers. Neither mentioned any type of maintenance, nor was there any information included in the manufacturer's packet.
Until I read this thread, my assumption was the bearings were sealed and maintenance free.

Dromen

05-22-2012, 10:29 AM

same here

Ahneida Ride

05-22-2012, 11:11 AM

The first iteration of DKS used bushings not bearing ...

Just saw a 12 year old DKS bushing in great shape.

Jeff N.

05-22-2012, 05:12 PM

Wondering if this system is still incorporated on the Meivici as well. Jeff N.

Ahneida Ride

05-22-2012, 05:23 PM

Nope ... only in the Ottrott I do believe.

perhaps the carbon stayed Legend ?

gone

05-23-2012, 07:56 AM

Nope ... only in the Ottrott I do believe.

perhaps the carbon stayed Legend ?

I believe it's still available in the Legend ST.

happycampyer

05-23-2012, 12:31 PM

Wondering if this system is still incorporated on the Meivici as well. Jeff N.My understanding is that it was never incorporated into the MeiVici. There is a bolt, but no bearing. Iirc, Serotta made prototypes of the MeiVici with the ST bearings, and concluded that they did not provide any benefit to the ride quality in the case of the MeiVici.

Jeff N.

05-23-2012, 12:57 PM

My understanding is that it was never incorporated into the MeiVici. There is a bolt, but no bearing. Iirc, Serotta made prototypes of the MeiVici with the ST bearings, and concluded that they did not provide any benefit to the ride quality in the case of the MeiVici.I'd say that's a pretty accurate conclusion...for ALL models. I wonder if you could just use the bolt on other models and just toss the bearings? Jeff N.

zap

05-23-2012, 03:04 PM

I'd say that's a pretty accurate conclusion...for ALL models. I wonder if you could just use the bolt on other models and just toss the bearings? Jeff N.

You can and helps quite a bit to add much needed rigidity to that design but still not as good as a solid rear end.

Chance

05-24-2012, 08:11 AM

You can and helps quite a bit to add much needed rigidity to that design but still not as good as a solid rear end.

Are there not two potential issues with this proposed alteration? When a bearing (free rotational movement) is replaced with a bolted connection (presumed rigid or it would loosen over time) loads and therefore stresses carried by seatstays and chainstays are altered. A rider could end up inadvertently damaging a frame because stays can�t flex as designed.

Secondly, wouldn�t a �solid� rear end ride harsher? Eliminating bearings makes the rear stiffer which normally means stiffer ride. Would that not be like riding with super stiff aero wheels or 120 PSI in tires? Seems like it would be going backwards for a person who bought a more forgiving frame in the first place.

If it were me, would try to do routine maintenance; although it sounds like a real pain. Rotating bearings 90 to 180 degrees should help extend life some. Bearings don�t like to take impact loads in one position which seems to happen in this application. Probably why they don�t last longer.

gone

05-24-2012, 08:26 AM

Are there not two potential issues with this proposed alteration?
If I recall correctly, one option that Serotta offered was a "lockout" that essentially replaced the bearing with a solid bolt. I was asked if I wanted that the last time I had the bearings replaced, I didn't so I don't know any more details than that.

Anyone else know for sure?

zap

05-24-2012, 08:53 AM

Secondly, wouldn�t a �solid� rear end ride harsher? Eliminating bearings makes the rear stiffer which normally means stiffer ride. Would that not be like riding with super stiff aero wheels or 120 PSI in tires? Seems like it would be going backwards for a person who bought a more forgiving frame in the first place.

I recall Serotta offering a bolt kit but it's still not good enough. It really needs a more solid connection.

Comfort is in the position. Ride is all about performance, will tires stay on the ground better in bumpy corners.

akelman

05-24-2012, 09:05 AM

I recall Serotta offering a bolt kit but it's still not good enough. It really needs a more solid connection.

Comfort is in the position. Ride is all about performance, will tires stay on the ground better in bumpy corners.

Just to clarify, you're saying that a rigid rear end is more likely to stay planted in bumpy corners? Or the opposite?

zap

05-24-2012, 09:59 AM

Ahh, the problems with quick, short and incomplete response. I hit the submit button without realizing it.

One can certainly write a novel about all this but based on my experience as a former category racer/current cycling enthusiast......

Tire selection and pressure is sufficient to meet performance criteria for given road conditions.

The Serotta ST design has gone too far on the "woopy" scale for a performance kit and I found (short test ride) under certain extreme conditions (I hit a speed bump pretty fast) that the ST rebound was too severe and the rear would lighten up. Maybe if I had ridden the ST more I would compensate but with so many excellent frame choices out there, why bother.

Chance

05-24-2012, 10:58 AM

The Serotta ST design has gone too far on the "woopy" scale for a performance kit and I found (short test ride) under certain extreme conditions (I hit a speed bump pretty fast) that the ST rebound was too severe and the rear would lighten up. Maybe if I had ridden the ST more I would compensate but with so many excellent frame choices out there, why bother.

Nothing is perfect. We can only minimize the bad with intelligent tradeoffs. Specifically the bad that comes up more often or has greatest downside potential.

Yes, you are right that under some circumstances an extremely mild suspension like that of an ST can rebound the tire more so than a firmer frame�s. There is no doubt it can happen. On the other hand a firmer frame will more likely bounce the tire off the pavement under more usual circumstances. You can�t solve both. Take your pick.

For me hitting a speed bump pretty hard (or anything similar) is not something that should happen on a road bike very often. Can say that in many years of riding have never hit anything approaching a speed bump square on without warning. Hence unloading the bike or jumping over it solves that problem. Not a big fan of the ST design but that doesn�t mean that the softer ride doesn�t improve performance (and comfort) in other ways.

What�s hard to follow is why Serotta would offer a �fix� that deactivates part of the design�s featured function. It�s almost like accepting defeat and admitting that it doesn�t work as flawlessly as initially claimed.

Jeff N.

05-24-2012, 11:06 AM

There is absolutely no need for ball bearings there. There, I said it. Jeff N.

HenryA

05-24-2012, 05:58 PM

I don't think the bearing is needed either and I also doubt the bearing design makes the rear end too "whoopie". The ones I've ridden did just fine. I do agree that you want the rubber planted on the road at all times.

93legendti

05-24-2012, 06:45 PM

ST will keep your rubber planted more than the extact bike without the ST.

So if the question is "do all suspension systems absorb/waste/use ( choose your favorite or add your own here) energy?". Or maybe the question should be changed to " does any or all frame flex result in a loss of energy?". Um....nope.

As I understand it the energy would need to go somewhere. It's not turning into light so it must turn into heat. I don't know about your bike but mine never gets hot when I ride it.....not even warm.

Think of it like a ski or a driving board. They certainly can absorb energy but they also return it back in a way that we like. It's all a matter of damping. The ski and diving board have almost zero damping so they don't use/waste/absorb energy. Damping in suspension systems is where the energy goes. Think about how much work the shocks on your car do. They don't actually hold the car up but they slow the movement of the spring so provide better and more consistant contact between the tire and the road. The shocks on your car/MTB/motorcycle...etc. get hot when they move up and down. The springs don't because they aren't permanently deforming, they are just flexing. My MTB shock will got pretty darn hot after a long down hill. Not the sprin but the oil damping unit.

So how does this apply to the ST or the Hors. Cat? Both of these have stays that act like a diving board for the most part but they are a bit different from each other. The ST, with it's very limited amount of travel, doesn't require any damping......there's just not enough movement to slow down. There's no bounce with the ST. The Hors on the other hand benefits from a small amount of compression damping due to it's longer travel. The Hors has no rebound damping at all. It was experimented with but had no real benefit so it was axed. One might feel that they are slower on a given system because it's "wasting " the energy but it's just not so. You may be slower but I contend that the frame movement isn't the direct cause. One thing that can happen is that the rider may not be pedalling in synch with the movement of the system. Anyone that has ever sprinted a full suspension MTB across a a smooth parking lot will know this feeling. But watch the guys who can pedal with the bike and not against it and they can fly.

Dinner time.....

Dave

http://forums.thepaceline.net/newreply.php?do=newreply&p=239328

akelman

05-24-2012, 06:59 PM

ST will keep your rubber planted more than the extact bike without the ST.

That was certainly my experience. I owned two Ottrotts. One had ST stays, one didn't. Both were set up exactly the same way (Record groups, hand-built wheels, etc.) and both had the same geometry (both were stock 56s, both had level top tubes, both had head tube extensions). The ST version descended steep, windy, pitted roads better than the non-ST version. The ST version also felt much, much stiffer laterally. Honestly, it was the only bike that ever felt laterally stiff and vertically compliant to me. Was it all in my head? Who knows.