Comments on: Road bikes with disc brakes

By: motorbike_designer

motorbike_designer — Fri, 16 Nov 2012 01:54:23 +0000

Simple physics. Dics brakes require stronger wheels. Stonger wheels mean more weight.
If a disc brake capable wheel weighs the same as a sheet of A4 paper the discless one can be made even lighter.

The last place a rider would want to add weight to bike is the wheel.
Rotating mass doubles on acceleration so for example if a bike weighs 6kg (4kg fixed mass, 2kg in rotating mass ), that same bike will weight 8kg when accelerated.

Saying this I hope they do accept disc brakes but I know this is little to do with safety and more about lining the manufacturers pockets.
Whatever happens in the peloton transfers more effectively to the public and there is far more profit in expensive disc brakes than rims.

By: Kimmo

Kimmo — Fri, 13 Jul 2012 13:18:26 +0000

Fignon, who rode after LeMond, lost 58 seconds during the stage, and although he became third in the stage, he lost the lead to LeMond. It was calculated afterwards that if Fignon had cut off his ponytail, he would have reduced his drag that much that he would have won the Tour.

http://en.wikipedia.org/wiki/Laurent_Fignon#1989:_losing_by_8_seconds

By: Kimmo

Kimmo — Fri, 13 Jul 2012 13:14:16 +0000

Yep, the Colnago pictured here is fail.

By: John

John — Sat, 09 Jun 2012 19:04:49 +0000

The problem could be solved by mounting the brake in front of the fork, so that the force vector at the hub is upward instead of downward.

By: art

art — Wed, 14 Mar 2012 23:23:53 +0000

This has nothing to do with wheel durability. Most riders take neutral wheels because of flat tires.

By: Androo

Androo — Wed, 14 Mar 2012 23:20:05 +0000

*gasp* You mean you might need to make bikes and wheels strong enough to last for an entire stage? I wonder if that would be a more useful way to spend the ballast weight that they require to get up to the UCI 15 lb minimum, instead of dropping extra lengths of chain down the seat tube…

By: art

art — Wed, 14 Mar 2012 13:04:39 +0000

I know everyone likes to bash the UCI, but remember that there’s no neutral service in cyclocross. That makes it a lot easier to allow a variety of equipment.

It’s bad enough that the neutral cars at road races need to carry two sets of rear wheels for different cassette spacings. If all manufacturers could be talked into using the same rotor diameter and exactly the same rotor offset, it would only double the number of wheels in play. Maybe that’s alright in a stage race, but neutral service in a lot of the spring classics is done by motorcycles with only four spare wheels.

By: art

art — Wed, 14 Mar 2012 12:49:15 +0000

Since you seem to understand dynamics so well, could you please enlighten us as to why disc brakes are dangerous?

By: Nicholas Hardrath

Nicholas Hardrath — Tue, 13 Mar 2012 18:00:45 +0000

I would love to take you on the challenge of speed of removing the two types of brakes; guaranteed hydraulic would take you longer. I can pull my mtb. bike wheel off and replace a tube in less than 1 minute, can you? Can argue the rim width issue, even on my road bike swapping training to race wheels requires either a slight adjustment or common sense in buying similar width rims (current trend says wider is better). I also use Campagnolo and swap out brake pads when switching. I still like the simplicity and keeping it simple – why change what works good?

By: Androo

Androo — Tue, 13 Mar 2012 00:33:11 +0000

It’s likely the dropouts are forward angled (as on the 3T Luteus cyclocross fork). Problem solved. Mountain bikes with much bigger rotors used regular QRs for a decade.

The option for more power that discs offer certainly doesn’t hurt, but there are definite benefits in terms of rim wear, rim weight, tire clearance, wheel swappability, and wet weather performance.

I expect that ultimately weight will be about even with discs, and chances are aerodynamics may even be a bit worse, but I think races are won by riders and not impossibly marginal variations in weight and aero on the bike, and so the improved confidence that disc brakes will offer can’t be underestimated.