Why choose a larger TT frame?

[DarkWing]

Hi.
I'm in the process of buying a FELT DA (timetrial) and I don't know what size to choose.
I'm 192cm tall, and I'm not quite sure if I should choose the 56 or 58.
I don't know what the advantage of a 58 would be.

Due to the UCI rules there can't be more than 75cm (80cm for taller riders) from bottom bracket to the tip of the aerobars. Which means a larger frame wont do me much good.
The advantage of a smaller frame is the fact that the headtube is lower. The advantage of the larger frame, is the wider wheelbase - which effect that has... I don't know.
I'm assuming I would be able to raise the seatpost of the 56 frame to acommodate my height?
Unforutnately I haven't been able to find a dealer where I live - so I can't try one out before buying. I hope you can help

To sum it up, why choose a larger frame when the length of the bike is limited by the UCI and a lower bike would make me more aerodynamic - and still allow me to have the same seatpost height?


Thanks.

 

[gogo419]

unless your racing UCI calendar events or State or National events that you know check the ruling with aerobar length from BB and stuff you do not need to worry at all about it. Looking by your height you should definitly get a 58 what size is your road bike?

 

[runninboy]

Hi.
I'm in the process of buying a FELT DA (timetrial) and I don't know what size to choose.
I'm 192cm tall, and I'm not quite sure if I should choose the 56 or 58.
I don't know what the advantage of a 58 would be.

Due to the UCI rules there can't be more than 75cm (80cm for taller riders) from bottom bracket to the tip of the aerobars. Which means a larger frame wont do me much good.
The advantage of a smaller frame is the fact that the headtube is lower. The advantage of the larger frame, is the wider wheelbase - which effect that has... I don't know.
I'm assuming I would be able to raise the seatpost of the 56 frame to acommodate my height?
Unforutnately I haven't been able to find a dealer where I live - so I can't try one out before buying. I hope you can help

To sum it up, why choose a larger frame when the length of the bike is limited by the UCI and a lower bike would make me more aerodynamic - and still allow me to have the same seatpost height?


Thanks.

Have u tried riding the different sizes? For me i found the larger frame much better handling, why? Because on a TT bike your weight is not equally distributed between wheels like a road bike. You are riding a steeper angle seat tube and resting on your elbows. on a larger frame your weight is further behind the front axle making the handling more stable & not as twitchy IMO

 

[davidg]

fwiw - I would buy the smallest frame I could get away with. I ride 54 road and 51 TT. I believe Cancellara rides 58 road and 54 TT (at least did with Cervelo) and he is 1.86m tall.

Lighter, more aero.

I would be surprised if having a larger frame made that much difference to stability, once you are set up, since your body is a fixed size and half of the difference in frame size is behind you in any case and not affecting the steering as much.

 

[mherm79]

I would be surprised if having a larger frame made that much difference to stability, once you are set up, since your body is a fixed size and half of the difference in frame size is behind you in any case and not affecting the steering as much.

not sure if TT bikes have the same handling as standard road bikes, but i've gone from a 56 -> 60 based on my inseam of 880mm. i've found that the longer wheelbase has made a huge difference to handling. the 56 was easier to throw around into corners, the 60 holds it's line more.
head tube hieght is about the same on both bikes coz i raised the 56 when i realised the frame was too small for me