Check out the way Slipstream’s mechanics have set up their rear wheels. You could drive a team bus through that gap between the wheel and the seat post. Am I missing something, or isn’t the point of horizontal dropouts to allow the rear wheel to get in really close to the seat post? I can get the rear wheel on my B2 to rub the post if I really wanted, so it’s certainly possible to run it very tight. Is there some reason to run it so far away?
(On another note, those graphics are pretty wicked.)
Tires with latex tubes bleed air due to the porosity of the tubes. So my guess is that the tires are just not inflated fully. May also be that they run them further out for training to prevent rocks and such getting pulled into the cutout during roads that may not be swept (as most TT roads are swept).
Tires with latex tubes bleed air due to the porosity of the tubes. So my guess is that the tires are just not inflated fully. May also be that they run them further out for training to prevent rocks and such getting pulled into the cutout during roads that may not be swept (as most TT roads are swept).
Maybe this is the way someone (probably not the mechanic) put the wheel on for the photo shoot. Im guessing it wasn’t someone who knew alot about the aerodynamics of wheel placement, probably some marketing guy.
No, this is the setup for the TTT. Here’s another picture from that day’s stage; this is the team mechanic tuning up.
Jordan’s rock theory is the only thing that I thought of, but it seems like a risk you’d take in a big race. Since the tire is moving down at the seat post, a rock would almost certainly have to come in from the top to get stuck. Even on regular roads this seems unlikely. Have any of you had problems with rocks getting stuck in this gap?
Besides stick and stones, I remember when close fitting wheels and cut outs first were popular, (yes before Cervelo) hearing that you didn’t want them too close. The reasoning was that the tire would drag air into the narrow gap and high pressure would build up. I think this was tested by C Kyle.
I know at least one thread talked about how many ST had the paint scraped off the cut out on Cervelos. It seems that would be too close.
whoever took those pictures should’ve ironed the sheet that they’re using as a backdrop. maybe they pulled it off their hotel bed after they slept on it …
the officials used to check the gap by inserting a credit card that had to be able to pass through without bending. don’t know if this is still the method used, but that would explain the tire not being pushed in as close as possible. a few mm isn’t worth a dq.
the officials used to check the gap by inserting a credit card that had to be able to pass through without bending. don’t know if this is still the method used, but that would explain the tire not being pushed in as close as possible. a few mm isn’t worth a dq.
Ding Ding Ding. Finally, we have the correct answer.
Yes, I know of that rule, but you could slip my entire wallet through that gap! There has to be 3/4 of an inch between the tire and the outer edges of the seat tube.
The aerodynamics theory is an interesting one, though. It wouldn’t be the first time the best aerodynamic arrangement was counterintuitive (e.g., Bento boxes).
SuperDave, is there some Felt wind tunnel data you want to share with us all?
Except that the gaps in the pics are way larger than a credit card width. I think the real answer is that most pro mechanics are way less picky about minor details than the average STer. They want the bikes to get from point A to B without any malfunctions. You aren’t going to find many taping over valve holes on disc wheels or turning skewer levers horizontal.
In looking at the first picture I note that the height of the tires they are using is very small. In the second picture it looks like they have the brake pads pulled all the way up in the brake caliper. So maybe the answer is that to insure proper brake pad contact with the rim they had to leave the wheel farther out?
Man, I don’t know. After dropping all that dough on wind tunnel testing and the most aerodynamic equipment available (from their sponsors, at least), it seems crazy that the mechanics would just disregard some fundamental set-up rules for maximizing aerodynamics. That’s why the bigger-gap-is-more-aero theory seems interesting to me. The only other alternative is that there is a practical reason to forego the aero advantage of a tight spacing, like avoiding rock jams, though I think that is less plausible.
I really hope Pro Tour mechanics care about little details like this.
