Re: Rake (was:Re: [CR]postscript)


Example: Books:Ron Kitching

Date: Thu, 24 May 2001 17:40:30 -0700
From: Brian Baylis <rocklube@adnc.com>
To: Huthornton@aol.com
Cc: classicrendezvous@bikelist.org
Subject: Re: Rake (was:Re: [CR]postscript)
References: <c1.e8731de.283ee6f6@aol.com>


Hugh,

Sounds like interesting research. Count me in for a donation of $5. Now get busy and figure this all out for us. Good Luck!

Brian Baylis Anxious for the results; is it done yet?
>
> In a message dated 24/05/01 16:38:49 GMT Daylight Time,
> monkey37@bluemarble.net writes:
>
> > Let's hear for some of the engineers on the list on this one. Through my
> > personal experience I feel that bikes with lots of quick rake at the ends
> > of the fork blades have a more comfortable front end. The only way I
> > could think of it was like a leaf spring. I've hear all kinds of
> > anicdotial information, but I want to see some science.
> > enjoy,
> > Branmdon"monkeyman"Ives
> >
> You are right that bicycle design is short on science and long on good
> experience, anecdotal evidence and just plain rubbish. Even Mike Burrows'
> book "Bicycle Design" is short on science, but he does debunk a lot of myths
> and separates a lot of the nonsense from the sense. Cycle magazine road
> tests and product reviews compound the problem by authoritatively pronouncing
> complete rubbish -- a hilarious example of which is contained within the
> latest issue or "procycling" which says of the Serotta Legend Ti Race Frame
> that ".. an S-bend increases power transfer through the chainstays." -- may
> sound convincing but is science fiction (or, to be more accurate, total
> garbage).
>
> That said, I am sorry to say that, as an engineer, I do not have the answers.
> I can say that my relaxed angle bikes with long fork rake ride comfortably
> and the forks appear to flex merrily as I ride over rough surfaces. My track
> and aluminum bikes appear "harsher" or less comfortable. But I seem to
> recall that Mike Burrows in his book provided data that showed that frame
> flex is negligible compared with tire flex, which I am almost prepared to
> believe. In which case, what we perceive as comfortable or uncomfortable may
> have more to do with the frequency, rather than amplitude, of vibrations
> experienced by the rider. There may be some good research on this topic, but
> I am not aware of it. The answers can only be found by carefully constructed
> experiments (which I should be delighted to design and carry out if
> appropriate funding were forthcoming).
>
> Sorry I can't do better -- perhaps some of the other engineers have some good
> data they can share with us.

>

> Hugh Thornton