Re: [CR]Frame stiffness

(Example: Racing)

Date: Mon, 10 Mar 2003 15:15:27 -0800
From: "Steve Maas" <>
Subject: Re: [CR]Frame stiffness
References: <A5E72E8AE73AD311954A009027887CFFC392CC@SLSERVER>

Actually, it looks to me like one of the better jobs of measuring this kind of thing. It's not just a measure of the BB stiffness. The bike is supported at the drop-outs, and the force is applied to the BB, much as if it were by the rider's weight.

The point of making such a measurement is not just the simple result; it is sometimes to obtain data that can be used to estimate what happens in different conditions. For example, the fact that they used a 60 KG weight is irrelevant. Greater forces will simply result in proportionately greater strain.

I've seen a few such "frame stiffness" measurements published, and some are pretty good, some not. The uniform conclusion, however, is that the perception of differences in frame flexibility is not real. See, for example, the FAQ at, and especially the conclusions.

Steve Maas Long Beach, California

Grant McLean wrote:
> I don't want to debate the benefits of
> stiffness, or the idea of measuring only
> the bb stiffness and making conclusions from
> that data, but isn't the method here flawed?
> I would think the rider can generate force
> beyond only their body weight?
> The conditions shown make it look like the
> flex is only a couple of mm, "so what's all
> the fuss about" could be someone's conculsion.
> That doesn't look too "real world" to me:
> Grant McLean
> Toronto.Ca
> O \O/
> _< \_ _< _
> (_)>(_) (_)>(_)
> _______________________________________________
> .