Who uses a road geometry bike as their race bike?

[guru]

I went from roadie to probably 80% tri geek. I use my road bike fitted with aerobars... feel very comfortable and seem to be fairly fast... anyone else happy with the road geometry during races?

[TysonB]

For many years I used a '69 Peugeot U08 with "classic" Scott aerobars. It was fine and the Peugeot has especially "relaxed" geometry with reliable downtube shifting. LOL! This year I have acquired and really like my early '90's Merckx MX-Leader road bike with Profile Design aeros. It is more adjustable and I have it pretty dialed in, even though it, too, has the saddle significantly behind the bottom bracket. I am a 58-year old age grouper who enjoys finishing in the top half of my age group and occasionally passing full on disc-wheeled TT bikes on the road. I race strictly for fun.

Please know that TT specific bikes have significant advantages in some areas. The big one for me is that a TT bike that fits you will keep you from "binding up" at the upper leg-hip juntion. Once used to a TT bike, I believe you will find it more comfortable while in the bars. Also be aware that sometimes even accomplished riders have a hard time getting used to a new TT bike and don't really see much improvement at first. Others rocket off on the first sitting. I am thinking especially about a young (and apparently flexible) 2nd year rider in our group who just went from mid-group to the head of the class in the two months since he acquired a full carbon Trek.

Hope this ambiguous response furthers your decision making process.

Tyson
Cushing, Oklahoma

[Bayin]

I use a 2002 Avanti Sprint with ITM bars and have never looked back, one of the fastest bikes I have even ridden.

[Hammer40]

I ride a Cannondale CAAD 9 road bike with Carbon Stryke aerobars. So far so good, however as my tri's are getting longer I'm considering buying a tri specific set up.

[Bayin]

There was an acticle in this months issue of TMSM in OZ about using your road bike as a Tri bike and had a few changes you could make to it to get you in a better aero position, after reading it I realised I'd already made all the changes they suggested.

Glad I'd done something right.

[roadpig2001]

I have a 54 cm centurion lemans that is a little on the small side for me as a road bike. But a s a converted tri bike it is great. I use a carbon fork and flipped a thomson setback seatpost to get a good position. It is very comfortable, has a slack headtube angle and handles great. I usually place top 10 in my age group on the bike segment. I used a caad 5 road setup this year on a race that I previously used the centurion on and my time was off . May have been me but I think it was the bike.

[JeffOYB]

I started another thread about issues related to this. Offhand, I would think that when you use a road bike with aerobars you suddenly put a LOT more weight on the front wheel---also the weight moves upward some since aerobars on a road bike are generally higher than riding the tops/hood---both of these changes must really impair handling. How have you adapted your road bike to deal with this? Of course, one could just put up with a wobbly ride.

I have several ideas that might be relevant---one might be to install a low-trail fork which would have much less fork-flop and would respond much less to shifts in body weight. Low-trail forks are traditionally used on bikes with front loads. Seems like it might make sense to use one on a tri/TT bike. However, I have NEVER heard of this being done with a tri or TT bike. Hmmm! I haven't done it myself---I've just put up with a wobbly road bike with aerobars.

Now I've also tried to ask about this subject at rec.bicycles.tech where, thanks to their interest and expertise in bike science and potential, I got several replies saying that tri/TT bikes don't have to handle good---they only go straight and not in a pack. Ignorant, eh? Pitiful. All bikes MUST handle as good as possible. Surprises OFTEN occur while out training or in any race/event. Many tri's and many elite TT's occur on challenging courses. Long TT's are a handling challenge always, as are the rare TTT's. So much for "handling doesn't matter"...

How to move a rider back and down while retaining the open hips position and stretch out on aerobars? Now we're talking a new frame. : ) I don't see how it can be done with a standard road bike. I'll restate much of my other thread, in case this one gets more traffic.

I note that achieving open hips with a road bike is done by moving the saddle forward---which puts even more weight out onto the front wheel. Or with a common tri/TT bike it's done with a steep seat tube---which also moves weight forward---and which tends to result in a short top tube. And who knows what other changes.

To get a much better tri/TT bike I would think you'd need a frame with short chainstays and a curved seat tube to move the rider while also moving the BB rearward (keeping a steep seat tube angle). Doing this would result in a short wheelbase bike...unless you lengthened out the top tube. So use a long top tube. Now install a short stem and low/integrated aerobars. And use a low-trail fork.

Between all 4 of these unusual changes it seems like you'd end up with a bike that handled good, rode straight and had equal weighting on the wheels. It may well even be suitable for installing brakes at the ends of the aerobars (since the aerobar position would no longer give one a dangerously high center-of-gravity for braking)---a great safety boon. ...But this kind of frame doesn't exist that I've heard of.

[Ryon]

I started another thread about issues related to this. Offhand, I would think that when you use a road bike with aerobars you suddenly put a LOT more weight on the front wheel---also the weight moves upward some since aerobars on a road bike are generally higher than riding the tops/hood---both of these changes must really impair handling. How have you adapted your road bike to deal with this? Of course, one could just put up with a wobbly ride.

I have several ideas that might be relevant---one might be to install a low-trail fork which would have much less fork-flop and would respond much less to shifts in body weight. Low-trail forks are traditionally used on bikes with front loads. Seems like it might make sense to use one on a tri/TT bike. However, I have NEVER heard of this being done with a tri or TT bike. Hmmm! I haven't done it myself---I've just put up with a wobbly road bike with aerobars.

Now I've also tried to ask about this subject at rec.bicycles.tech where, thanks to their interest and expertise in bike science and potential, I got several replies saying that tri/TT bikes don't have to handle good---they only go straight and not in a pack. Ignorant, eh? Pitiful. All bikes MUST handle as good as possible. Surprises OFTEN occur while out training or in any race/event. Many tri's and many elite TT's occur on challenging courses. Long TT's are a handling challenge always, as are the rare TTT's. So much for "handling doesn't matter"...

How to move a rider back and down while retaining the open hips position and stretch out on aerobars? Now we're talking a new frame. : ) I don't see how it can be done with a standard road bike. I'll restate much of my other thread, in case this one gets more traffic.

I note that achieving open hips with a road bike is done by moving the saddle forward---which puts even more weight out onto the front wheel. Or with a common tri/TT bike it's done with a steep seat tube---which also moves weight forward---and which tends to result in a short top tube. And who knows what other changes.

To get a much better tri/TT bike I would think you'd need a frame with short chainstays and a curved seat tube to move the rider while also moving the BB rearward (keeping a steep seat tube angle). Doing this would result in a short wheelbase bike...unless you lengthened out the top tube. So use a long top tube. Now install a short stem and low/integrated aerobars. And use a low-trail fork.

Between all 4 of these unusual changes it seems like you'd end up with a bike that handled good, rode straight and had equal weighting on the wheels. It may well even be suitable for installing brakes at the ends of the aerobars (since the aerobar position would no longer give one a dangerously high center-of-gravity for braking)---a great safety boon. ...But this kind of frame doesn't exist that I've heard of.

I absolutely love your analysis. Though I wonder, with a standard road frame with aero bars on it, would the increase in % weight over the front wheel be that much more than when one is out of the saddle on a steep climb? Would that be a cause for concern at all in terms of structural/materials integrity?

[roadpig2001]

On my road conversion there is more weight on the front but it does not seem to have a negative effect on handling. The centurion oem fork has a 50mm rake, the carbon fork I am currently using has a 40mm rake which tightened up the steering significantly. My guess is that the weight distribution is very close to50/50 .

[JeffOYB]

On my road conversion there is more weight on the front but it does not seem to have a negative effect on handling. The centurion oem fork has a 50mm rake, the carbon fork I am currently using has a 40mm rake which tightened up the steering significantly. My guess is that the weight distribution is very close to50/50 .

I wonder if bumps hit harder when the front has more weight...

I note that "rake" tends to be the amount of forward bend. Longer rake mean LESS trail. Shorter rake increases trail and tends to increase fork-flop.

Handling is tricky stuff! It depends a lot on what we're used to.

I don't know how much wheel weight ratio change is significant. Who knows, maybe for steep, twisty descending a few pounds one way or the other might really matter, same with CoG.

My hunch is that experience is key---but I've heard that short trail improves ability to ride no-handed for one thing and also lets one ride a straighter line in general---like, it's easier to ride on the white stripe of the road, if you wanted to. Yet there's also more of a "light" feel. So it's hard to say.

I think that all my racing road bikes have had long trail, but I wonder if my 1993 RB1 might have the longest---it's actually fairly hard to ride no-handed and I hadn't experienced that before in a road bike. It seems like the front end really does like to flop---so maybe that relates to trail. I can ride it with aerobars no problem---but it makes me wonder how a low trail bike would feel with aerobars. So I'm asking around! : )

I absolutely love your analysis. Though I wonder, with a standard road frame with aero bars on it, would the increase in % weight over the front wheel be that much more than when one is out of the saddle on a steep climb? Would that be a cause for concern at all in terms of structural/materials integrity?

Thanks...it's all speculation at this point, though---til we find someone who has tested this stuff out.

I would think that slow climbing has different handling needs as compared, say, to fast descending.

I've heard that fork flop (from long trail---short rake!) can be a problem for slow mtbike climbing.

I have no idea what the materials limits are for bike stuff. Heck, I don't even know what the desired weight is for each wheel---I just think that changing it would have effects.

PS: I just found the tech articles at Slowtwitch that say much of what I do here. Cool! He doesn't seem to mention the benefit of lowering the CoG by lowering the BB---but he does suggest a low BB to improve cornering, so the change is in there but the reason isn't. (He gives a caution on pedal-strike---is this a risk with clipless?) He also goes on to say that tri bike builders aren't offering much yet that works with the desired geometry needs of tri. Bummer! (Few makers offer a long-rake/short-trail tri fork, he said.) He also mentions that he likes short-trail but seemingly for a different reason than I mention---he says it's twitchier. But it's more complex than that---it might also be easier to ride a straight line. Conversely, long trail can make a steadier bike in one sense---but one which wobbles when one's weight shifts slightly. It seems like each kind of trail has both a kind of stability and a kind of twitchiness. Pick the one that fits your sport best! It might be that short trail fits tri... He's also saying that he hasn't tested everything either (like me)... However, the Cervelo PC3 with its curved seat-tube might be getting there, at least in terms of wheel-weighting...

[Jagee]

Here's an interesting article with some good graphics:
http://www.bikesportmichigan.com/features/exisitingfit.shtml

I've got a 1989 Trek 1400 (with, of course, downtube shifters). I haven't done too much riding, but as I go along, I'm trying to tweak the ride. I put a shorter stem on to shorten the top length and may try what Roadpig mentioned--turning a setback seatpost around to bring me closer up to the bottom bracket line. I don't know if this will make the top length (i.e.- the top tube length) way too short, but with some aerobars, it could work. Only problem then is the downtube shifters! It may cost more than the bike is worth to upgrade those.

[Rahzel]

JeffOYB, your comments are pretty much spot on. I rode a Trek 1500 (http://www.martinmccrory.com/public/marty_aero_oct_2007.jpg) in a converted tri setup for a while. I was pretty low and in a decent position, but I ended up with a LOT of weight on the front wheel. That, combined with the short front/center, made for very quick and uncertain handling.

I currently ride a 2008 Giant Trinity Alliance (http://www.martinmccrory.com/public/giant_bike/marty_aero_may08.jpg), which has a MUCH longer front/center, and it is much more stable in the aero position. It's not nearly as twitchy. The weight distribution is much better, as well--still more weight on the front wheel than you'd get on your road bike in a road position, but it's much more comfortable, and much less stressful to ride.

Edit: Yeah, Dan Empfield over on Slowtwitch has a nice article talking about tri bike handling. I think one of the reasons you don't see tri bikes with a longer front/center is UCI regulations. Although triathletes aren't bound to UCI regs, it's a lot tougher to sell a bike when all of the sizes above, say, 54cm have a too-long front/center :)

[TysonB]

As to how well TT bikes handle and go around corners, ask Zebriski (sp?) (Team High Road) or Rasmussen (Rabobank). Both are famous crashers on their TT bikes. Rasmussen (AKA "the Chicken" because of his looks, not his courage) crashed 3 times! in a TT stage of the Tour of France a couple of years ago. Zeke crashed for no apparent reason in the team time trial at the Tour while leading.

TT bikes ARE designed for going straight. Not that handling doesn't matter at all, but in the compromises riders are willing to make for a good aerodynamic position, increased weight on the front wheel is a fact of life at this point in bicycle development. Your respondents on the tech forum weren't necessarily being facitious. The road bike with the seat slightly further back than optimum for power, will still be reasonable stable.

TysonB

[maddmaxx]

If you read all of the articles that are available on TT/TRI bike design you may begin to see a pattern of 2 different styles of bikes depending on the nature of the course.

1. If the course favors staying on the aerobars all or most of the time, then the TT framed bike is superior from an aerodynamic point of view. One of the design features here of great importance is a very short head tube that gets the bars down as low as possible. This then requires the upright seat tube etc that makes up the rest of the design.

2. If the course requires a lot of off the bars climbing or technical handling in crowded places (including draft legal races) then the road frame begins to look like a good alternative. The road frame is often fitted with shorter aero bars. This latter feature may be in part to keep front weight down. Many times to get the body lower, a road framed TT bike will not use arm cups but will require the rider to rest his/her arms on the top of the drop bar. A rider cannot get as low on this style of bike because of the relaxed seat tube and relatively longish head tube.