Where's the flex?

[pjmsj21]

I have noticed on my Fierte It, that when I set the sensor for my computer within just a few mm's away from the magnet, that I notice that it rubs against the spoke and I get a clicking sound with every revlolution. I notice this only when I am out of the saddle and swinging the bike from side to side to aid in acceleration.

So while I know what the easy fix is...just move the sensor farther from the spoke, I am curious as to whether the wheel is flexing or the fork?

Thanks.

Pat Mc

[thwart]

IMHO, 9 times out of 10, it's the wheel.

[Pete Serotta]

Willing to bet you it is the wheel......I am assuming it has an 02 or an S3.

[pjmsj21]

Pete the fork is an S3 and the wheels are Shimano Ultegra WH-R600's which feature 20 spokes up front. Thanks for the info.

Pat Mc

[Nautilus]

Have you tried lining up the sensor and flexing the wheel by hand?
Should make the flex pretty easy to find.

Also, make sure that there isn't any play in the hub, try quickly flexing the wheel back and forth across the rim to test for play.

[TimD]

It is probably the fork. You should buy the F3 10.5 I have listed in the Classifieds :)

Seriously, most probably the wheel. Borrow a Ksyrium and try that.

[RPS]

I am curious as to whether the wheel is flexing or the fork?
Both.

Technically speaking, any part that is stressed under load flexes some. The only questions are how much and in what direction.

When most riders lean a bike to its side to pedal hard out of the saddle, they have to apply a moment at the bars to counter the forces being applied at the pedal(s). This places a side load at the wheel which must cause “some” flex and also places a side load on the fork which must cause “some” flex there too. Having said that, I’d personally expect more wheel flex below the axle and less above the axle where the computer’s transmitter is mounted.

I’ve noticed this problem also but not at the magnet/sensor but rather at the brake pads when adjusted too closely. Every time I stood to climb my front rim would touch the brake pad with each pedal stroke; or was it the brake pad touching the rim? :argue: