Olympic cycling 2024

[Chargeride]

Silk tubs in my day, Ive ridden a concrete track in our local area about 45 years ago, it was actually pretty easy.

 

[Chargeride]

Confusing (to me) track events this morning: Men's omnium and women's keirin. Generally no clue as to why some riders choose to go high on the banks when they do.

The bikes are aero in the extreme, but no one's riding a front disk wheel.

A hard top-speed 3-rider crash in the first heat of the women's keirin quarterfinals sent wheel disk shrapnel flying everywhere. Race-delaying track repairs ensued.

All of this prompted the commentators to spend some time talking about the unsung heroes of Olympic cycling— the bike mechanics — and the pressures they face.

And that got the cameras to dwell on the centerfield pit area. Must've been a zillion dollars worth of bikes there in various stages of assembly and repair!

Watching it with the missus pretending I know the rules, yeah the guy at the front drops back..and has to go the otherside of the line for half a lap...and then he can slipstream off the other team...if..hes got enough points from the previous day...
Wifes eyes to start to slit.

 

[Jeremy McCreary]

Not sure why they use disc's on the rear only but with as much time as teams spend in wind tunnels there has to be a reason. It was news for the mens time trial that Wout VanAert used a front disc on his bike and he medaled but who knows if it made the difference as the other medalists didn't.

I've heard and read more than once that front disks mess up bike handling — especially but not just in crosswinds. And that makes some sense physics-wise.

This wisdom was repeated quite emphatically on GCN, where one pundit put Van Aert's gain at only 3W per wind tunnel testing. Not worth the risk in a TT, he said.

The pundit with him had heard 17W but didn't believe it. He wondered if the front disk would have worked out so well for a rider with less upper body strength than Van Aert.

Of course, I have no way to judge. I just find it an interesting engineering question.

 

[mschwett]

I've heard and read more than once that front disks mess up bike handling — especially but not just in crosswinds. And that makes some sense physics-wise.

This wisdom was repeated quite emphatically on GCN, where one pundit put Van Aert's gain at only 3W per wind tunnel testing. Not worth the risk in a TT, he said.

The pundit with him had heard 17W but didn't believe it. He wondered if the front disk would have worked out so well for a rider with less upper body strength than Van Aert.

Of course, I have no way to judge. I just find it an interesting engineering question.

i believe the issue is that with crosswinds, the center around which the lateral force is exerted with a disc (or even really deep) front wheel starts to move forward, and if it gets past the center of gravity of the bike/rider system, the wind rotates the bike (around the vertical axis of the CG) in a way that leaning does not effectively counter. you don't want to try to steer against gusty winds, you want to lean into them and resist being pushed sideways with your mass. resisting being rotated is much, much harder since you don't have much or any weight over the handlebars.

i believe the rule of thumb for racing bikes is that around 55% of the weight is on the rear wheel. if you have the same lateral force front and rear, not good!

on the other hand, a disc up front has a bigger impact on aero than in the rear, since it's the leading edge. i've never ridden one but it must be damn sketchy if pros aren't doing it when more than a few seconds could be saved.

around here, most long rides involve crossing the golden gate and so even strong, experienced riders avoid deep section front rims (to say nothing of disks!) because the crosswinds are so strong and so gusty. sometimes i've been leaned over so far that the width of the path was a problem when passing another rider!

 

[Jeremy McCreary]

around here, most long rides involve crossing the golden gate and so even strong, experienced riders avoid deep section front rims (to say nothing of disks!) because the crosswinds are so strong and so gusty. sometimes i've been leaned over so far that the width of the path was a problem when passing another rider!

I used to commute the Golden Gate Bridge on an 1100 cc Suzuki — including through the apocalyptic winter storms of 1982-83. I can vouch for the crosswinds. My motto at the time: "Hey, you can only get so wet."

 

[mschwett]

I used to commute the Golden Gate Bridge on an 1100 cc Suzuki — including through the apocalyptic winter storms of 1982-83. I can vouch for the crosswinds. My motto at the time: "Hey, you can only get so wet."

it’s even worse on the bike path, which is right at the western edge! roadway and east pedestrian path are better!