I was wondering if TT bikes are lower than their road bike counter parts. If they aren’t why not? Lower would be more efficient, right? It looks like the Blue TT bike has a bend in the chain stay which would put the bike lower but on other makes the chain stay appears parallel with the road (therefore normal in height). Am I wrong, whats up?
Some are - fact of the matter is that most folks who WANT a “low” front end cant fold over their bellies to RIDE a low front end. The common thought is that a spine that is = to the road surface is faster. What a body can do at a 40k TT is one thing, what we see at IM on the same bike is another. It is really slower to have a low bike that you can not ride on the aerobars than a higher bike where you can (and for the distance, not for a block or two)
It’s difficult to lower the front end much lower than it currently is. If you lowered the BB without lowering the top of the headtube, you’d sacrifice position, and be slower.
Also, a lower BB means less pedal clearance while cornering.
Maybe you misunderstood or perhaps I was unclear. If you lowered the whole bike frame you would keep the geometry the same but the bike would be lower. Yes, the cranks would be closer to the ground but that wouldn’t always hinder one’s ability to navigate a TT course. The reason I asked this question is because some roadies sit on their top tue while decending, I was under the impression it was to lower their center of gravity, but I guess it may be simply more areo. I am not sure, thats why I am asking.
the bottom brackets are not generally lower no.
and while it has been suggested that this would make the bike more aerodynamic, i dissagree
there is some speculation that certain aero bike makers use HIGHER bottom brackets to achieve straighter, and thus more aero, chain stays
I was wondering if TT bikes are lower than their road bike counter parts. If they aren’t why not? Lower would be more efficient, right? It looks like the Blue TT bike has a bend in the chain stay which would put the bike lower but on other makes the chain stay appears parallel with the road (therefore normal in height). Am I wrong, whats up?
650 bikes are lower all around
but not more aero
Maybe you misunderstood or perhaps I was unclear. If you lowered the whole bike frame you would keep the geometry the same but the bike would be lower. Yes, the cranks would be closer to the ground but that wouldn’t always hinder one’s ability to navigate a TT course. The reason I asked this question is because some roadies sit on their top tue while decending, I was under the impression it was to lower their center of gravity, but I guess it may be simply more areo. I am not sure, thats why I am asking.
I thought the 650 bikes were more areo, but that was based on just my thinking no hard fact. I see you point about the straight chain stays and that makes sense to me. Thanks!
the bottom brackets are not generally lower no.
and while it has been suggested that this would make the bike more aerodynamic, i dissagree
I am a person that has always thought lower to the ground would be more aero. It’s definitely a splitting hairs type of comparison but here are some advantages I can see:
lower to the ground = lower environmental wind conditions. (the lower to the ground you are the lower the wind, I don’t know when this stops being important but hey I did say splitting hairs right?)
Lower to the ground means a smaller frontal area total.
Lower bottom bracket means a shorter headtube. I’d have to imagine that a 1cm shorter headtube is more of an aerodynamic advantage than chainstays that have to make up that distance.
chainstays and head tubes have pretty similar shapes.
the head tube is up front
but the chain stays, there are two =)
we need aero chain stays!
I am a person that has always thought lower to the ground would be more aero. It’s definitely a splitting hairs type of comparison but here are some advantages I can see:
lower to the ground = lower environmental wind conditions. (the lower to the ground you are the lower the wind, I don’t know when this stops being important but hey I did say splitting hairs right?)
Lower to the ground means a smaller frontal area total.
Lower bottom bracket means a shorter headtube. I’d have to imagine that a 1cm shorter headtube is more of an aerodynamic advantage than chainstays that have to make up that distance.
the bottom brackets are not generally lower no.
depends on the bike. there are plenty out there that ARE lower, and a lot of the first TT bikes (the 96 GT’s come to mine) where lower. My GT funny bike seems to be around 76-78mm of BB drop.
and while it has been suggested that this would make the bike more aerodynamic, i dissagree
I’m kinda of the mind that it might help a tiny amount, but so little it’s not worth worrying about (coming from a guy who worries a lot). I say this because in theory, the rider will be ‘covering’ more of the bike with a lower BB, all else equal. I also think this would be very difficult to control all of the variables and test legitimately, and the difference may be within the noise of the test.
there is some speculation that certain aero bike makers use HIGHER bottom brackets to achieve straighter, and thus more aero, chain stays
I don’t think there’s really ‘speculation’, I think there’s marketing/explaining by a company that uses a rather high BB on it’s TT bikes. Particularly in the current day of carbon, there’s zero reason to make a BB higher if level seat stays are the goal