Frame question

Dan, your assumptions are in line...

Yes most bicycle frame capacity issues are stiffness issues not strength
issues.

Bicycle stiffness is one of those "it depends" things... e.g. If you have a
good spin, it's not as important... how much you weigh... etc..

I might put emphasis on stiffer main tube(s) rather than the stays.

On Wed, Nov 4, 2009 at 1:28 PM, Dan Silvernail wrote:

> Here is a question for those frame experts out there (framebuilders and
> others).
>
> Or another way of stating it: if I weigh 160 lbs, what would the
> difference be if I put 40 lbs on the rack compared to a 180 lb rider putting
> 20 lbs on the rack? The gross weight would be 200 lbs either way.
>
> I have a good idea what the answer will be: the way the weight is applied
> to the bike.
>
> So, as a follow up, if I were to have a framebuilder build me a frame (like
> a ccx or sport-touring frame, not a racing frame) that would be able to
> carry an extra 30-40 lbs, how would the construction differ from one rated
> for less, such as 20 lbs? Stiffer chain and seat stays?
>
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--
jms, pe pdx, or
http://bikeeng.blogspot.com/


Dan Silvernail

2009-11-04

Here is a question for those frame experts out there (framebuilders and
others).

If a bike is rated to carry an extra 20 lbs of cargo on a rear rack, how
would that differ from a rider who is 20 lbs heavier? Or another way of
stating it: if I weigh 160 lbs, what would the difference be if I put 40
lbs on the rack compared to a 180 lb rider putting 20 lbs on the rack? The
gross weight would be 200 lbs either way.

I have a good idea what the answer will be: the way the weight is applied
to the bike.

So, as a follow up, if I were to have a framebuilder build me a frame (like
a ccx or sport-touring frame, not a racing frame) that would be able to
carry an extra 30-40 lbs, how would the construction differ from one rated
for less, such as 20 lbs? Stiffer chain and seat stays?