Road Cycling - bac wheel tire is not true

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extomesm
11-12-03, 07:32 PM
i just realized my rear wheel is not spinning true. this could be the result of a crash i had earlier this fall but just didnt notice it till now. it is only a slight deviation maybe like 1-2 mm. is there any way to fix it,should i take it to the shop, or is a new wheel in order?

sch
11-12-03, 08:40 PM
I an assuming you have checked for cracks: either
around the spoke holes or on the braking surfaces
and found none and the spokes are ok. If the
wheel has 28-36 spokes then check spoke tension
by plucking the spokes around the wheel. Rear wheels
can have a marked difference in tension between the
cassette side and the other side, though if built
well this does not occur. All the spokes should have
roughly the same note. If the note varies where the
wheel hops it suggests a bent rim from the crash. This
might be improvable by adjusting the spokes but this
is one of the more arcane arts and best left to ones
who have done it before. If on the other hand the
brakes grab with every rotation of the wheel and either
make a noise or jerk then the rim is toast and will need
to be replaced at a convenient time. Cracks mandate
urgent replacement. If the rim does not snag on
braking truing is optional at the 1-2mm level if radial,
but if axial, truing should be attempted. Wheels with
smaller numbers of spokes are harder to true. Eight
spoke wheels almost impossible if the rim is the problem.
Steve
extomesm
11-12-03, 09:02 PM
thanx for the response. i dont think i would be the one to mess with the spokes, i'd prolly do more harm than good. wuts the difference between radial and axial movement? thanx again Austin

sch
11-14-03, 06:09 PM
Radial means motion in and out in the direction of the spokes, along the wheel radius. If viewed from the side the wheel hops up and down as it rotates.
Axially is sidewise wobble in the direction of the wheel axle, and is seen looking
down on the wheel from above. It is worse because there is greater risk of brake interference. Again the most important factor is do the brakes grab the
rim at any single area when applied at 15-20mph, if so replace the rim, if not then truing, if possible, will be mostly cosmetic. Steve