RE: [CR]Frame flex and double blind tests

(Example: Racing:Jacques Boyer)

In-Reply-To: <MONKEYFOODbLAX3cf3e000006e9@monkeyfood.nt.phred.org>
References:
Date: Fri, 5 Aug 2005 07:50:24 -0700
To: classicrendezvous@bikelist.org
From: "Jan Heine" <heine93@earthlink.net>
Subject: RE: [CR]Frame flex and double blind tests


Comparing bicycles is very difficult for several reasons:

1. There are so many factors involved. Does one bike feel different from the next due to frame flex, Q factor, tires, etc. You can eliminate a lot - most of my randonneur bikes use the same cranks, wheels and handlebars. But you still are left with frame geometry vs. frame materials. Does my old Singer absorb more shock because of the longer fork rake or because of the thinner fork blades? (I recently rode a Singer with less fork rake and the same blades, and it was almost as shock absorbing, so it appears to be the latter... unless there is a difference I have overlooked.)

2. Every ride varies. One day, a certain road feels smooth, the next day you rattle through every pothole - on the same bike!

For builders, there is an additional problem:

3. Nobody really knows what the stresses involved are and why some bikes feel better than others. The current mantra is "laterally stiff and vertically compliant." Even if it were possible to design bikes that way, it does not appear that this would lead to either fast or comfortable bikes. For decades, riders have believed that frame flex robs energy and makes them slower. Yet most riders prefer lightweight frames even on the flats! And a lightweight frame will be more flexible than a heavier one. My stiffest bike ever was my first Peugeot 10-speed (made from "103 Carbolite" drainpipe tubing). I could carry my girl-friend on the seat while I was pedaling standing without a problem, when her bike broke on a ride. I later tried that with my (not superlight) Mercian touring bike, and it was almost unrideable due to frame flex. Would I pick the Peugeot for a flat time trial? Absolutely not!

When I test bikes for VBQ, I try to eliminate as many of the factors as possible:

1. I use the same tires, where possible. If not, I use the tires on the test bike on my "reference bike" (my daily rider, a Rivendell), and go for back-to-back rides on the same course.

2. I ride the same, familiar courses. So I know what my other bikes feel like on certain road surfaces, how they handle on certain windy descents, how they feel climbing certain hills.

3. I ride the bike for at least 2 weeks on and off to get a real feel for it.

4. If there is something obvious, like a much wider Q factor, I test the bike with the original cranks and then replace the cranks with some that match my other bikes.

5. Another tester also rides the bike, and we compare our impressions, if at all possible.

This allows me to inject a measure of objectivity into the tests, but even so, the result is that it is a bike that works well (or less well) for me and my riding style. If somebody else pedals at a much lower cadence, weighs a lot less and climbs every hill standing, they might not like this bike at all!

Finally, testing like this is a tremendous amount of work. I can see why Bicycling tests a bike by going for a spin of 20-25 miles and write their test. Of course, their verdict might have been entirely different if the bike's tires had been replaced before the ride.

Jan Heine, Seattle
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
http://www.vintagebicyclepress.com