Bicycle Mechanics - switching freehub and redishing

I am planning to switch my freehub (cassette body) from shimano to campy. American Classic sells a new freebody for my hub and provides instructions to make the switch.

The instructions seem very straightforward execpt for redishing the wheel. I am mechanically inclined and been working on bikes for a while now but not sure what "redishing the wheel" is? That being said, how would I go about doing it?

Also, as a side note I am not sure I understand why it needs to be done? Isn't redishing centering the rim over the axle? if so, shouldn't the axle already be centered on the rim? Why does swapping a freehub require redishing if the difference between a shimano and campy cassettes are splining and index spacing?

Lots of question and no answers...thanks in advance for sheding some light here.

Regards
Dave

Unless the distance from the hub flange to the dropout has changed I see no reason for re-dishing the wheel. Re-dishing should be a part of any good truing job, however.

Al

The rim is centered over the axle ends (actually over the locknuts) as you said. So if a wider freehub body is fitted, you have to remove a spacer from the non-drive side to keep the over-locknut dimension the same. That moves the rim to the left and you should recenter (redish) the wheel to put the rim back on center.

An inexpensive "dishing tool", actually a centering gauge, is a worthwhile purchase.

Ok, after doing some searching and reading the replies I "get it". Here is another question, in my estimations there should not be a great change in the centering of the rim (by switching the cassette body). Looking at the directions there is a 1.5mm washer to install for campy freehub vs. shimano.

Can anyone guess if I would need new spokes as I redish the wheel because either the drive/non-drive side spokes would be too long/short; respectively. What I am getting at is would I need to get new spokes to redish the wheel for adjust a 1.5mm change in the distance from the hub to the dropout?

Regards,
Dave

Ok, after doing some searching and reading the replies I "get it". Here is another question, in my estimations there should not be a great change in the centering of the rim (by switching the cassette body). Looking at the directions there is a 1.5mm washer to install for campy freehub vs. shimano.

Can anyone guess if I would need new spokes as I redish the wheel because either the drive/non-drive side spokes would be too long/short; respectively. What I am getting at is would I need to get new spokes to redish the wheel for adjust a 1.5mm change in the distance from the hub to the dropout?

Regards,
Dave

Probably not, it depends upon the length of the existing spokes and how much dishing needs to be done. If the side that needs to be tightened is nearly out of thread, then maybe.

I've redished several wheel when going from 7-speed to 8-speed Shimano freehub bodies and never had any problem with spoke length. You should be fine.

When doing the recentering you should tighten the drive-side spokes a half-turn and loosen the non-drive side spokes a half-turn and see where that puts you. Redishing requires a surprisingly small amount of spoke adjustment so don't do too much initially.

When doing the recentering you should tighten the drive-side spokes a half-turn and loosen the non-drive side spokes a half-turn and see where that puts you. Redishing requires a surprisingly small amount of spoke adjustment so don't do too much initially.

I would turn the nipples no more than 1/4 turn at a time, probably less than that.

Al

I concur w/ HillRider and Al. Also, if your frame is straight, you can conveniently use it as your dishing tool. You are correctly dished when the position of the rim does not change if you flip the wheel around. (If the rim is always off-center to the same side of the brake pivot bolt, then your frame is not symmetrical.)

Thanks for all the help! However, I just found out that for these wheels (American Classic Mag 300) I need to use a device that holds the spokes (not aero spokes) so that they do not twist. I cost of the tool about the same as taking it to a shop ($20-25) to redish.

Thanks for all the advice though...if not for me then for someone else that is reading.

Regards,
Dave