S
Spacey Spade
Guest
Dear Sheldon Brown,
Thank you so much for your web pages devoted to cycling.
I would very much like to see a torsional test on bicycle frames where the frame is held by the
wheel axles, and the deflection measurements are at the bottom bracket due to loads on the bottom
bracket. This would be a simple simulation for in-saddle hammering (when arms are not used). Is
there some test results published already?
For the test you could use a 1" steel bar in the steerer as in a previous test of yours, making sure
to afix the bar on the axis where the front axle would be (and not allowing it to rotate there, but
allowing rotation in the steerer tube... either that or use the same forks on all frames hehe!). You
could even put weights on the saddle and on the handlebars to make it even more lifelike.
Having owned a Schwinn Premis, now a Cannondale, I really appreciate the torsional stiffness from
the Cannondale. On the Schwinn I used to look down and see the bottom bracket swinging from side to
side under load (and the chainring would rub the front derailleur to the same tune if I didn't have
it adjusted right).
Regards,
Spacey BSME
Thank you so much for your web pages devoted to cycling.
I would very much like to see a torsional test on bicycle frames where the frame is held by the
wheel axles, and the deflection measurements are at the bottom bracket due to loads on the bottom
bracket. This would be a simple simulation for in-saddle hammering (when arms are not used). Is
there some test results published already?
For the test you could use a 1" steel bar in the steerer as in a previous test of yours, making sure
to afix the bar on the axis where the front axle would be (and not allowing it to rotate there, but
allowing rotation in the steerer tube... either that or use the same forks on all frames hehe!). You
could even put weights on the saddle and on the handlebars to make it even more lifelike.
Having owned a Schwinn Premis, now a Cannondale, I really appreciate the torsional stiffness from
the Cannondale. On the Schwinn I used to look down and see the bottom bracket swinging from side to
side under load (and the chainring would rub the front derailleur to the same tune if I didn't have
it adjusted right).
Regards,
Spacey BSME