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View Full Version : Tri bike geometry: low trail improve handling for forward position?




JeffOYB
05-29-08, 11:34 PM
I recently asked this on rec.bicycles.tech and the triathlon Google group and didn't get informed responses, so I'll try here!

Has anyone tried a low-trail fork on a bike with aerobars?

Has anyone tried designing a tri bike that brings the rider's weight-ratio and center of gravity back more to "normal"? Doesn't the aerobar position tend to move weight forward and CoG up a bit?

It seems offhand that designing a frame that moves the rider back and down a bit plus uses a low-trail fork might result in a bike that handles better while riding the aerobars.

The classic French bikes which were designed for carrying loads up front (either handlebar bags or front baskets) had a low-trail fork---to give improved handling and stability, etc. This is a design feature that has been somewhat lost but is now being revived as front loads become popular again in certain sectors (long distance randonneuring, for one; citybike for another). Probably the neglect of the low-trail idea was also due to the influence of the long-trail Italian road-bike, which I'm guessing has a 50-50 wheel-load ratio. Anyway, I was wondering if the classic French approach might have a benefit for tri-bikes. ??

Info based on knowledge/experience appreciated! Thanks! --JP allbikemag.com

HiYoSilver
05-30-08, 01:51 PM
slowman did the opposite. normal tri geometry frame and increased trail. cf slowtwitch, tech articles

JeffOYB
05-31-08, 01:49 PM
slowman did the opposite. normal tri geometry frame and increased trail. cf slowtwitch, tech articles

Oh, I get it---it's another website. OK, I found it and see that they have some neat tri geometry info there. Offhand, it looks like they recommend short trail, long rake like I'm suggesting. They also mention similar tri bike problems... Will study up and see what else they come up with! Thanks --JP

Rahzel
05-31-08, 08:08 PM
Yep, what you're saying makes sense--see the response I wrote to you in the other thread. Though I think the overall front/center length (more is more) is basically what's desired here, the low-trail, high-rake, high-headtube-angle forks and frames seem to be the best way to accomplish that. It's a shame we don't see many tri bikes that fully embrace this philosophy, though I think that the governing bodies of cycling may be partly to blame :)

StanSeven
05-31-08, 08:28 PM
I'm not sure what you want to accomplish. Can you elaborate?

If the bikes used regular bar positions, I can understand the issue. But riders are stretched out using forearms as much as hands/wrists for steering. Handing on tri bikes is relatively "slow" compared to a road bike.

StanSeven
05-31-08, 08:32 PM
I also should add that tri bikes are designed so save the rider's hamstrings for the run. You want the postition forward to use the quads more and save the hamstrings