Re: [CR] Why no Quick Releases on Track bikes (veering further OT)

<jerrymoos@sbcglobal.net> Cc: <classicrendezvous@bikelist.org> Sent: Wednesday, May 09, 2007 5:41 AM Subject: Re: [CR] Why no Quick Releases on Track bikes (veering further OT)

> My experience is quite the opposite of Galens. I've ridden fixed gear with
> QR for 25 years or so and have never had a problem with slippage. This
> includes when I was a reasonably competitive 170 lb cat.3, and using a 68"
> gear in hilly terrain (up and down) that I probably should have had sense
> enough to avoid. I converted a Pista hub to QR after leaving home without
> a 15mm wrench once too often!
> One caveat, I do use front and rear brakes, although I do try to decend
> most of the time as if they're not there. I've been glad in emergencies
> that both of them are!
>
> Best regards,
> Wes Gadd
> galen pewtherer <dolface@gmail.com> wrote:
> I can only speak from the experience of trying to ride a fixed gear on
> the street with QR's (never tried it on the track); they slip, no
> matter hard you crank them down.
>
> Caveats/details: I ride daily in San Francisco without handbrakes, and
> have done so for a number of years now, and I'm NOT a power guy. I
> weigh about 140lbs soaking wet, and my time in the flying 200 is
> embarrassing, but I regularly (read every ride) slewed the rear wheel
> around in the dropouts/trackends.
>
> Your slippage may vary.
>
> Galen 'Bolted on' Pewtherer
> San Francisco, CA, USA
>
> On 5/8/07, Jerome & Elizabeth Moos wrote:
>> I am sure he will correct me if I misquote him, but I believe Sheldon has
> often taken the position that all this talk about the tremendously higher
> forces on track bikes is a lot of foolishness, a combination of vodoo
> scien
> ce and trackie macho egos. I don't agree with Sheldon on everything, but I
> agree on this.
>>
>> Regards,
>>
>> Jerry Moos
>> Big Spring, TX
>>
>>
>> Jerry Prigmore wrote:
>>
>>
>> >
>> >Date: Tue, 08 May 2007 17:48:04 -0400
>> >From: genediggs(AT)aol.com
>> >
>> >...Velodrome racing puts much more stress on the bike frame than you do
> in
>> >the average road race. You just can't get the torque level required to
>> >keep from pulling the rear wheel, on a standing start, with a quick
>> >release cam mechanism....
>> >
>>
>> I respectfully disagree.
>>
>> Assuming equal-length crankarms, the smaller the chainring, the greater t
> he
>> mechanical advantage applying said pulling force to the chain and rear
>> wheel. Smaller gear = more force. (The size of the rear cog affects the
>> torque applied to the wheel [larger cog = more torque], but doesn't aff
> ect
>> to as great an extent the force attempting to pull the drive side of the
>> wheel forward in the fork end). The typically longer cranks on a road bik
> e
>> would further increase the mechanical advantage.
>>
>> Sprinting up a steep hill on a road bike in the small ring would apply mo
> re
>> pulling force to a rear wheel than would sprinting on the track. It may b
> e
>> counterintuitive, but it is simple physics. I can't address the differenc
> e
>> in power applied by a beefy track sprinter versus a wispy grimpeur.
>>
>> The cam action of a properly closed QR can apply an enormous closing forc
> e,
>> and unlike a nut, will not loosen, due to the over-center action of the c
> am.
>> However, "properly closed" is key, so it might make sense for a velodrome
>> official to ban QRs to be on the safe side. At least in a litigious socie
> ty
>> accustomed to acommodating the lowest common denominator, that is.
>>
>> Jerry Prigmore
>> Clovis, California, USA
>>
>> _________________________________________________________________
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>

>

> --

> -galen