Paging RPS

[timto]

Can you tell us more about the frame pictured in your avatar? Was curious - and wanted to know more...

i'm talking about this little fella
http://forums.thepaceline.net/image.php?u=2356&dateline=1215027725


Tim

[Pete Serotta]

Have you tried his email? Also as of today we think his RPS ID is able to be posted from. HE sent a note to me Pete@serotta.com


IF still a problem, please let me know. PETE

[ergott]

I rode with him in Texas once. That bike's pretty cool. I hope he can elaborate here. He's a good guy and a positive force around here.

[Ray]

Haven't seen RPS around here since March or April, IIRC. I don't know what went down but somehow I think there were some hard feelings involved, big arguments, and then he was just not here anymore. I'm pretty sure it was after political talk had been banned so I don't think that was it. Whatever, he's a very smart guy who I thought had a lot of interesting insights, even when I disagreed with him. A less interesting place without him.

I think he may have explained that bike at some point too, but I have no memory of what he said about it.

-Ray

[rugbysecondrow]

Haven't seen RPS around here since March or April, IIRC. I don't know what went down but somehow I think there were some hard feelings involved, big arguments, and then he was just not here anymore. I'm pretty sure it was after political talk had been banned so I don't think that was it. Whatever, he's a very smart guy who I thought had a lot of interesting insights, even when I disagreed with him. A less interesting place without him.

I think he may have explained that bike at some point too, but I have no memory of what he said about it.

-Ray

I thought he was running from the law...

or was it a sex change operation...

maybe he is an operative ala Valerie Plame..

maybe it was all of the above...I don't remember so good no more. ;)

[timto]

Have you tried his email? Also as of today we think his RPS ID is able to be posted from. HE sent a note to me PEte@serotta.com


IF still a problem, please let me know. PETE

Before I posted I had tried the PM and the Email forum options but it said that the user had turned them 'off'. So I went public but thanks I just tried again and it looks like they went through... I'm just so curious about road designs and really excited about what David Kirk is outing, the DKS, the Terraplane and I think what RPS had done was something in a similar vein.
I like seeing people attempt to push boundaries and put their money where their mouth is. Kudos to Serotta, DK and all the trail blazers. Now hopefully we can find out more about RPS's bike!

[William]

Before I posted I had tried the PM and the Email forum options but it said that the user had turned them 'off'. So I went public but thanks I just tried again and it looks like they went through... I'm just so curious about road designs and really excited about what David Kirk is outing, the DKS, the Terraplane and I think what RPS had done was something in a similar vein.
I like seeing people attempt to push boundaries and put their money where their mouth is. Kudos to Serotta, DK and all the trail blazers. Now hopefully we can find out more about RPS's bike!

I'm pretty sure he discussed his design on the forum in the past. I don't remember much about what he said but it was when more builders were here on the forum...pre V-Salon.

Mine the forum and you'll probably find it.



William

[RPS]

Haven't seen RPS around here since March or April, IIRC. I don't know what went down but somehow I think there were some hard feelings involved, big arguments, and then he was just not here anymore. I'm pretty sure it was after political talk had been banned so I don't think that was it.
You are correct Ray – it was not political. I was banned for being rude to other members. I did not know at the time that it is considered inappropriate and therefore unacceptable to ask a member why he geared his bike the way he did. I should have accepted a reprimand, apologized to Dave, and moved on but since injustice is my hot button in life I reacted inappropriately to what I considered at the time to be blatant bias and abuse of power against me. If I was rude to Dave for asking such a question I do apologize to him since I did not mean in any way to be antagonistic. Like Dave I am also technical and peer critiquing of designs is a normal occurrence (its even encouraged by many), so in my defense I did not think for a second I was doing anything wrong. Apparently I don’t get the rest of you and what you consider normal behavior as well as I thought.

Not that it excuses my reaction, but to make matters worse soon after that my wife and I were in an auto accident which left her seriously injured and me a little banged up, which in turn overwhelmed me with new responsibilities I was not ready for. Maybe being a little down and perhaps a little too angry at the world in general I challenged Pete over the injustice of banning me instead of trying to resolve the issue constructively. For that I apologize to Pete for I should have just ignored the entire thing and accepted his censorship rather than becoming angry at him. Pete, I’m sorry I got angry at you and hope you recover soon. I may have been angry at you as a moderator but never as a person.

[RPS]

Can you tell us more about the frame pictured in your avatar? Was curious - and wanted to know more...

i'm talking about this little fella
http://forums.thepaceline.net/image.php?u=2356&dateline=1215027725


Tim
Tim, sorry for not getting back to you sooner but I did not respond to you earlier because I couldn’t, not because I was ignoring you.

I received your e-mail yesterday and will respond to your many questions but it will take me a little time. The level of detail in your questions and the amount of thought you’ve put into this is surprising.

[malcolm]

RPS, has been around awhile and while I don't know him personally his posts and thoughtful responses/replies is part of what keeps me coming back. I'm glad to hear hard feelings are being put aside and look forward to greater participation again. Good luck and speedy recovery to you and your wife.

[Keith A]

RPS -- Thanks for posting your message :)

[Pete Serotta]

I could have been better at the initial discussion also... BEER or WINE on me when we meet and I can drink again....


My Irish gets me at times!! :crap: :crap:


PETE

[Keith A]

I could have been better at the initial discussion also... BEER or WINE on me when we meet and I can drink again....


My Irish gets me at times!! :crap: :crap:


PETEI'm not a drinking man myself, but do know a little...but I have never heard of anyone drinking Been " BEEN" :beer:



(Yes I know it was a typo)

[Pete Serotta]

IS Serotta Beer :) It has been used at Saratoga and at the Serotta last open house...... :beer: :)

[Ray]

Not that it excuses my reaction, but to make matters worse soon after that my wife and I were in an auto accident which left her seriously injured and me a little banged up, which in turn overwhelmed me with new responsibilities I was not ready for.
Wow, Rick, I'm very sorry to hear. I'm glad you're apparently OK - I hope you wife either is OK or is on the road back and will recover fully. Little internet squabbles are put very quickly in perspective by events like your accident and Pete's illness. In any case, I'm glad you're back, to whatever extent. Seems like a somewhat less active place lately, my own involvement has been greatly reduced, but its probably more civil. For what its worth, I went back and read that last discussion, at least the public parts of it, and I couldn't even begin to figure out what the problem was. But good its resolved, in any case. Your voice has been missed.

-Ray

[93legendti]

Welcome back RPS.
Sorry to hear about your accident. I hope you and your wife heal quickly.

[Climb01742]

Your voice has been missed.

+1

rps, best wishes for your and your wife's recoveries.

when it feels right, i hope you rejoin our disfunctional little sandbox. diverse articulate opinions add a lot.

[Pete Serotta]

I hope you rejoin our dysfunctional forum. Diverse articulate opinions add a lot ALWAYS!!!! PETE

[RPS]

Wow, Rick, I'm very sorry to hear. I'm glad you're apparently OK - I hope you wife either is OK or is on the road back and will recover fully. Little internet squabbles are put very quickly in perspective by events like your accident and Pete's illness. (snipped)
Thanks Ray -- and legend and climb. I appreciate your kind thoughts.

Proper perspective can also keep us from wasting time worrying and agonizing over things we can’t control anyway. As cyclists and drivers we often talk about expecting the unexpected, like distracted drivers, maybe texting, or those in a hurry running a light, etc…, but I have to admit I didn’t give much thought to a driver going through a red light in the middle of the cycle and bringing us from 40 MPH to zero in less than a heart beat. The whole thing seemed almost instantaneous – a reminder of how quickly and unexpectedly a day can change for any of us. We were just a few miles from home and it was just another beautiful sunny Saturday afternoon like so many others up to that point. The whole thing was so senseless and so completely avoidable by just one person paying attention to what they were doing.

What really helped us was that thanks to cycling we were blessed to know two orthopedic surgeons from our club who I called for advice and a second opinion for treating her injured back. The ER surgeon had recommended and scheduled operating to stabilize the injured area but we (mostly I since she was in a lot of pain and/or pain meds) decided to take the more conservative approach which in retrospect seems to have been the right one. We can’t be certain we made the right choice because things can always change but for now it sure feels like we lucked out. On the other hand had I made the wrong choice on her behalf I’m not sure how I could have handled the consequences.

Having a cycling friend or two willing and able to help guide us was – as the commercial says -- priceless.


Sorry to drift – back to bikes.

[RPS]

Tim, thanks again for your interest.

Addressing the most important question first, I’d love to see qualified builders try the design for themselves. I’m sure some would be quite creative. I wouldn’t expect any compensation (I’m not trying to sell anything here which would be against Serotta forum rules anyway), but since I can’t control anyone’s judgment or the quality of their work I’d need to be released from liability prior to giving them a free license to build themselves a bike with the patented design. Basically I don’t want to be responsible for someone else’s shoddy work or lack of common sense (not suggesting that would be you). If you remain interested we can discuss a release later.

If you are interested in building a steel frame for yourself using this design and feel you have the skills to do so, I’ll help you any way I can and will share information with you as needed. Under reasonable circumstances I see few risks in letting qualified builders make themselves a frame or two of this design to test or just to play around with. Obviously I need to prevent some clueless person trying to build one in his basement out of conduit and then getting hurt or bitching that it didn’t work.

The following are answers to most of the questions you asked in no particular order. Because of length I broke down to a few topics at a time to prevent the whole thing being copied multiple times (should it happen at all) which fills forum pages quickly.

[RPS]

The Avatar picture is indeed of a Calfee which he built for Interbike. I sold the bike to a friend who helped me test ride and compare different bikes. My friend really liked the Calfee and it fit him better than me anyway. If it had been my size I would have kept it for sure.

Anyone who can build a normal steel frame should be able to build one like the one you described. I have a steel Schneider that is closer to what you asked about – except that you would prefer to end the upper chainstays at the seattube. You should be able to find a picture somewhere on the forum of my Schneider. In all honesty I haven’t done as much testing of that variant because I originally envisioned it primarily for small and/or very light riders.

None of the frames built have any pivots. They are not needed at all because there is very little relative flexing at the joints. That was by design and not a coincidence. I wanted to keep the highest suspension-related stresses at or near the center of tubes and away from welds where fatigue could be a greater issue. Pivots can also add to maintenance and reduce rear triangle torsional stiffness. If required I guess they are OK but I’d rather not need them in the first place.

[RPS]

Indeed the geometry of the dropouts has to be taken into account. The shape will likely need to resemble those used on suspension bikes or some recumbents. Unfortunately there are not as many available in steel. With smaller small cogs you can get away with a lot because you don’t need as much room for chain clearance. I could fit 11T and 12T small cogs on an early prototype that used standard horizontal dropouts. All my present bikes have plenty of room for standard cassettes (although I only use 11T or 12T anyway).

The chainstays (lower and upper since I didn’t call them “seatstays”) are NOT designed to bow (i.e. – flex or bend). Unlike frames that flex the seatstays to achieve wheel suspension I want as little flex as possible because it would contribute to rear wheel instability. Also in this design having stiff upper chainstays has a negligible effect on ride stiffness. I would not worry about making them too stiff other than it adds to frame weight.

The 22 mm travel of the titanium variant you mentioned (or most all of the travel of any of the frames for that matter) doesn’t come from the rear triangle as most observers may first think. In fact I’ve gone out of my way to make sure as little travel as possible comes from the rear triangle. The rear triangle could be very stiff (i.e. -- as in rigid) and it would still work pretty much the same, particularly on frames where the top stays continue to the downtube. Because of inherent leverage built into the frame geometry, significant rear wheel travel comes from a slight flex of main triangle tubes. Unlike curved seat stays that must flex a lot to let the rear wheel move a little, in this design a little frame flex generates more wheel movement. This keeps stresses down by comparison and allows more wheel travel without things breaking. By the way, I’ve intentionally pushed the ti frame to 22 mm but don’t know what the upper limit is. I just know it’s more than I need.

[RPS]

I have not had failures at all during normal or even during intentional abusive use and testing. Only during destructive testing have I damaged a frame, which is what I was trying to do to find the upper limits and failure mode. And even that “failed” frame can still be ridden. I haven’t seen the need to intentionally destroy a nice carbon or titanium frame unnecessarily at this time because non-destructive tests I’ve performed have shown a high-enough margin of safety compared to normal use. If someone was going to pursue mass production of any new design I think it would be wise to do multiple destructive tests, but for my own bike I feel it’s unnecessary.

Having said that, I wouldn’t count on a standard steel frame necessarily providing 22 mm of wheel travel – not that you need that much. It may but it may not – there are a lot of variables. Steel is much stiffer than titanium and not as strong compared to how far it will flex in the elastic range. Additionally, standard steel tubes you can purchase off the shelf for bike building are very thin and will likely fail first – when placed in bending -- due to localized buckling on the compression side. This is good because it is a safe mode of failure but it doesn’t allow the steel tubes to work up to their highest design strength. I know custom tube sets if designed for this application would enhance performance beyond anything I’ve done thus far with available tubes but custom requires a minimum order size I can’t justify for a few frames. For a frame like you described selecting the proper seattube would be important in many ways.

[RPS]

If the upper stays end at the seattube as you seem to like best for aesthetic reasons things change a little. For starters frame lateral stiffness would decrease some compared to the other variant (which I happen to prefer for myself). On the other hand the one you like provides a softer and more comfortable ride provided everything else is equal, but there are technical compromises involved I can’t discuss here very easily. As I stated above, originally I envisioned that layout for smaller and lighter riders, but if done right it should work fine for any size. Personally I’m biased towards function over aesthetics unless the difference is very noticeable.

Using a sloping top tube like you prefer should decrease maximum wheel travel slightly. Everything else being equal, shorter tubes flex less for the same stress. Also, one of the minor disadvantages of this frame design is that the seattube water bottle must be mounted a little higher to clear the upper stays (this limitation doesn’t apply to variant you prefer). This combined with a sloping top tube may limit the maximum size of the ST water bottle. On the flip side if you are so inclined a third water bottle can be added due to lack of seatstays. For hot centuries with few stops I’ve temporarily installed a clamp-on bottle cage behind the seattube to carry a third bottle.

Building a frame of this design in steel should be fairly easy for a skilled and experienced builder. You didn’t ask but I’ll tell you about one area that needs a little extra planning. The rear brake is more difficult to place than on a traditional frame. I’ve tried mini-Vs on upper stays, elongating chainstays slightly to fit a caliper between seattube and tire, placing the caliper under the lower chainstays just behind the BBKT, and also a rear disc (frame completed but bike not built yet). I haven’t tried the disc yet but the others work fine if planned and executed properly. I don’t see any reason why the disc won’t work great too. The frames I ride the most have standard road calipers because they are road bikes and I normally buy complete groups. I really liked mini-Vs but would only use them again on an all-around bike (which may be my next project). I don’t have all the answers and don’t claim to -- there are probably other ways to tackle this.

[RPS]

Damping is often discussed here and almost always becomes contentious; so I saved it for last. Our tendency is to think of road bike suspension like that of a car’s, or at a minimum like that of a motorcycle. I’ve been guilty in the past of using the comparison as an example and probably shouldn’t because it confuses the subject matter. Technically I think the differences are way too great to apply the same theories. I’ll cover just a few.

1) When optimized for road riding, suspension travel is far less; even when adjusted for travel speed.
2) The vast majority of the load the suspension carries is the rider, who can weigh about 10 times more than the bike.
3) The human body is far from rigid (unlike a car or motorcycle structure) and provides a lot of natural system damping regardless of the bike we ride.
4) Unlike cars and motorcycles, our pedaling motion creates a forcing frequency the bike suspension has to deal with. This limits spring stiffness selection.
5) Dampers (shock absorbers) are primarily used to dissipate energy after the suspension is upset. Their affect on vibration is another matter.

I’d rather not get into this too much since you didn’t ask specifically; just know that the amount of stored energy in the suspension spring system we are talking about here is relatively small; in large part because we are dealing with minimal suspension travel. While it is possible to make a case for the need to control rebound, I think in general it does more harm than good to incorporate some form of shock absorber into the suspension (again, mostly because we are typically talking about a few mm of travel, not inches). And on the occasional event we hit a large bump that may benefit from suspension energy dissipation, our bodies take care of that quite well. On the bikes I ride suspension movement damps out very quickly even without a shock absorber. Placing a 150 pound person on a bike is not the same as clamping 150 pounds of steel to that same bike -- the steel wouldn’t absorb energy and wouldn’t contribute to system damping at all. Basically I’m saying that a road bike with very limited passive suspension travel (by comparison) shouldn’t be analyzed like if it were a car. The main goal should remain that of reducing vibration and impact harshness.

Although I don’t think it does much good -- if any – and probably detracts from performance the other 99.99 percent of the time, I’m not against adding damping to the suspension if it makes the rider happy. The way I did it is similar to the device in your E-Mail’s link but slid down the seattube so that the elastomer is compressed when the seat tube flexes. When using such a damper arrangement care must be taken so that water bottle cage bolts don’t interfere. With added planning a cage bolt can be used to affix the damper in place so it doesn’t move up the seat tube. Friction does a great job too. Again, I think a damper is overkill and not needed unless suspension travel is far more than we are talking about here.


Hope I covered everything, and let me know if you need more info. And thanks again for your interest.

[AndrewS]

Any chance we could see a real photo of the bike? With only one side of the conversation posted, I really have no clue what the specifics are with this design.