Had this talk with TomD a while back. Bigger was the answer. How much would be something to talk to your fitter about

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Jim

**Note above poster works for a retailer selling bikes and related gear*

bump

Road bike with a longer toptube than your tri-bike. This assuming that you're well fitted on your tri-bike, and I'm not talking about matching colours ;-)

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"Yeah, no one likes a smartass, but we all like stars" - Thom Yorke


smartasscoach.tri-oeiras.com

Here's my sample:

5'9"

Road bike: 54 tt(set up at 54.5, 73deg effective)(9cm drop, saddle to top of drop bars)

Talon SL: 53.3 tt(set up at 52.5, 76.8deg effective)(12 cm drop, saddle to armrest)

QR Tequilo: 52.1 tt(set up at 51.6, 78.5deg effective)(13 cm drop, saddle to armrest)(the tt length is a guess, as I don't own this bike anymore...the measurements come from a log)

So...tri-bike...you should be longer...you ride a 55.5cm tt on your tri-bike...you should probably be 58-59 on the road bike...probably longer if you go for an upright commuter/touring position)...with the 58 tt you'd probably use a slightly longer stem, as well...maybe a 120-130 vice the 100-110 you've probably got on that tri-bike...that really depends on how low you mount your road bars

Time trial top tube: 55.5 cm
Road bike top tube: 56.5 - 57.5 cm

I think this depends on whether you ride your tri-bike steep or not. It also depends on how much drop (saddle to bar) you have on your tri bike right now.



If you are riding steep (as God and Gerard intended) and have a reasonable drop (also as Gerard intended based on the headtube on the P3) - then your road bike should definitely be larger. Most specifically, it should have a longer top tube.

But remember - this shouldn't be measured against the actual top tube on your tri-bike, but against the effective top tube.

For example - the length of the actual top-tube means nothing if you ride with a Profile Fast Forward seat post (or whatever that particular one was called). The P3 can go from 75 to 80 degrees (not sure of the exact spec) based on which position of the seat post you use and where your saddle is on the rails.



So - I think your answer is 'it depends'.

Is your tri bike designed to be ridden steep with a lot of drop? If yes - then your road bike should be 'bigger'.

Is your tri bike a designed to be ridden in a slack position (74-75 degrees)? If yes - then your road bike should probably be of a comparable size.



So - what tri bike are we comparing this road bike to?