Re: [CR]Scary Peugeot PX-10 steering

(Example: Events:Cirque du Cyclisme:2007)

In-Reply-To: <4548B8DC.20903@earthlink.net>
References: <MONKEYFOODlvvWnu0PF00002ae2@monkeyfood.nt.phred.org>
Date: Wed, 1 Nov 2006 07:55:58 -0800
To: jj and kk <designzero@earthlink.net>
From: "Jan Heine" <heine94@earthlink.net>
Subject: Re: [CR]Scary Peugeot PX-10 steering
cc: classicrendezvous@bikelist.org

John,

those measurements sound reasonably internally consistent. You get about 44 mm trail. So yes, unloaded, that bike should feel very light, and with tires narrower than 25 mm, it probably lacks stability.

That would be an interesting bike to try with a handlebar bag and 28-30 mm tires. It might be very nice, as the trail figure is similar to the J. P. Weigle Randonneur we tested in Bicycle Quarterly. However, that bike had a head angle of 73 degrees. The seat angle was shallower, putting the rider's weight back, but the chainstays were very long, putting more weight on the front again, etc... so it may feel very different. I haven't ridden bikes with 76 degree head angles, so this all is speculation.

I often have wondered why most bicycles use head angles of 71 to 74 degrees, with few exceptions. I have ridden bikes with 68 or so degree head angles, and even though their trail figures came out in the normal range, they were unpleasant. However, there were other factors, such as poor fit, etc., that make it hard to put a finger on what was wrong.

Clearly, head angle has a number of effects, perhaps the most important being wheel flop. Too much wheel flop, and the bike doesn't want to go straight at lower speeds. Too little, and the steering is hard to turn, because it lacks the "power steering" of the wheel flop reinforcing your steering inputs. -- Jan Heine Editor Bicycle Quarterly 140 Lakeside Ave #C Seattle WA 98122 http://www.bikequarterly.com