Re: [CR]Over Vesus Under - Who Among Us Is Where ?? plus trailquestion

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Date: Thu, 02 Jan 2003 20:15:13 -0500
From: "Doc Simont" <mdsimont@snet.net>
To: Olof Stroh <olof.stroh@hem.utfors.se>
Subject: Re: [CR]Over Vesus Under - Who Among Us Is Where ?? plus trailquestion
References: <008201c2b27c$efb80aa0$ca247044@nebi.com> <015901c2b28d$883b0f60$0200a8c0@salong>
cc: "C.R. List" <classicrendezvous@bikelist.org>
cc: "C.R. List"

Olof Stroh wrote:

<<--snip-->>
> These last days however I am ordering a Mercian Vincitore custom touring geometry for my daughter and letting them repaint a Colnago Super from 1976 for same daughter. Thought I could let the Centurion get my desktop 1010A dropouts and new cantilever braze-ons (instead of destroyed ones) placed for mtb wheels, whereby letting the bb go down those twenty mms as well as get plain, but decent, enamel while they already were at it. Took some measurement this afternoon and found that trail would lessen from 54 to 48 mms which is rather the opposite of my wishes.
>
> So my question to the collective experience here: how much does it matter? is it worth £75 for a new fork with less rake? and how do you measure rake - parallell to the ground or 90deg from the line through the head tube?

I did some web-searching a while back on the same subject and came up with the simple answer:

http://www.phred.org/~josh/bike/trail.html

and a more detailed answer:

http://spectrum-cycles.com/612.htm

Interestingly, Josh Putnam's page says 90 degrees from the steering axis and Tom Kellogg (or whoever at Spectrum) says in the verbal definition "leads the steering axis", which I would interpret as horizontal. (I personally have always assumed it was at 90-degrees - or did those master fork builders always know the head-tube angle of the particular fork they were building at the moment.)

Spectrum's piece was the only one I found that actually interpreted how the variations would affect handling (from the standpoint of fork geometry alone, though ;-( )

Doc Simont Cornwall, CT
>
> I admit this is just for the joy of making experiments and also that is is - at best - only half topic so forgive me Dale, but an answer would be nice.
>
> A very pleasurable 2003 to you all with lot of cheap and enjoyable backroom finds!
>
> Olof Stroh
> Uppsala Sweden