I have an older QA Te Quillo. 650cc wheels/78deg seat angle.
I’ve been looking at new bikes lately. I notice the Cervello’s say “adjustable seat angle” from 74ded - 78deg. I’m wondering how that is accomplished? Is this by just simply sliding the seat forwards and backwards?
And, if it’s accomplished by just moving the seat on the seat post, then doesn’t this have an effect that is different than riding a bike like mine which is 78deg by design? I would think just moving the seat forward will not give me the same geometry. I recall trying to buy a forward seat post for my old Trek 1200 road bike and it just wasn’t the same as riding a bike designed like my QR. I could go to sleep in the aero position on my QR…
Cervelo uses a flip around seat post in which the top turns 180 degrees. Gives about 4 cm of extra play or so. IMO, bikes with a fixed 78 degree post painted themselves into a corner in as much that if the rider wasn’t comfy steep there was little he could do other than get another bike with a more shallow angle. It was quite clever of Cervelo to make their tri bikes work from 74-79 degrees effective seat angle. This way they can be rode legally in the TDF TT’s with the seat 5 cm behind the BB or more forward if wanted.
No, there is a bit more to it. When you flip the post, you are basically shortening the top tube by 3cm, which means you need to lengthen the cockpit by 3cm or so, then lower the bars to maintain the angles.
So how does it work on a soloist. It’s advertised as just flip the seatpost around and you have a tri bike. Hmmm…do you also need to lengthen the cockpit?
Another subject - by sliding the seat forward or backward on the rails, how much effect does it have on the seat tube angle? 1 degree, 2, 3?
Flipping the post is the same as getting a forward post or sliding the seat forward on the rails. In all cases this shortens the top tube length, which means you need to lengthen the rest of the cockpit and lower it so the angles match up. Also, in all cases it changes your position relative to the bike, which can lead to handling problems on most road bikes which are not typically designed to be ridden like this. (soloist the exception?)
In general, I can’t understand the fascination with taking a road bike, which is designed for one type of riding, and screwing with the seat posts, stems and bars to make it a “tri” bike. Rarely will it work out well. The front-center and rear-center dimensions on a traditional road bike are just not designed to have all that weight on the front end. If you want a steep angled tri bike, buy one of those. If you want the best of both worlds, steep + road bike, it will be a tough order to fill.
Oh, for me, with a seat height of 758mm (measured from the BB), moving the seat forward 13 mm is roughly 1 degree. The lower the seat, the bigger the change in degrees.
Thanks, I suspected there was more to it just by the fact I’ve put forward seat posts on road bikes and it is just not the same fit and comfort of a tri bike.
So I guess the Cervalo of which I speak is really a road bike with road geometry - and a fancy seat post.
I find it interesting then that it comes with aerobars and the appearance of a tri bike.