Why re-dish a wheel if you're changing the type of freehub?

[Louis]

The more I think about this the more I get confused. I assume that the purpose of re-dishing a wheel is to center the rim between the lock-nuts or end-caps. But if all you're doing is changing the freehub from Campy to Shimano, or vice-versa, that shouldn't affect the rim position relative to the ends of the axle. Granted the freehub might move a little bit inboard or outboard, but all you need to do then is tweak the dérailleur position.

Perhaps the answer has something to do with the end of one brand of cassette moving outboard so much that it is too close to the dropout, but I wouldn't think that there would be that much motion. Which cassettes take up more space outboard, Campy, or Shimano?

Any explanations would be useful.

TIA
Louis

[oldpotatoe]

The more I think about this the more I get confused. I assume that the purpose of re-dishing a wheel is to center the rim between the lock-nuts or end-caps. But if all you're doing is changing the freehub from Campy to Shimano, or vice-versa, that shouldn't affect the rim position relative to the ends of the axle. Granted the freehub might move a little bit inboard or outboard, but all you need to do then is tweak the dérailleur position.

Perhaps the answer has something to do with the end of one brand of cassette moving outboard so much that it is too close to the dropout, but I wouldn't think that there would be that much motion. Which cassettes take up more space outboard, Campy, or Shimano?

Any explanations would be useful.

TIA
Louis

All the hubs I have converted, using the manufacturers freehub, not some aftermarket thing, has resulted in a dished wheel, no re-dish required(DT, Campagnolo, Powertap, Zipp....). Campagnolo cogset stacks are wider than shimano but the maker, if designed correctly, takes that into account.

[pitcrew]

White Industry rear hubs have specific drive side axle ends for either the Shimano/Sram freehub body or the Campagnolo freehub body. When you switch the freehub body one way or the other, you also switch the drive side axle end.

Assuming the wheel was dished correctly in the beginning, and small amount of dishing adjustment is needed once the (new) freehub and corresponding axle end are installed.

[Peter P.]

Louis, you're thinking right about this.

My guess is, the wheel manufacturers have conveniently left out the information that if the freehub body widths differ when swapping them, you HAVE TO MOVE SPACERS AROUND, THEN re-dish the wheel.

Otherwise you're certainly correct; there should be no re-dishing necessary.

[martinrjensen]

At least with Amererican Classic, if you go from Shimano to Campy, "re-dishing" is required.

[Black Dog]

If you replace the end caps and of the new ones; one is shorter and the other longer the wheel will move out of dish. The total axle length will not change. This is the case with the HED sonic hubs when you switch over.

If you switch you have to re-dish both ways. In another thread it was mentioned that this is not the case with HED (apparently HED said this), that you only have to dish going to campy and not back. That is wrong. You have to dish both going both ways. HED will confirm this as will simply doing it...perhaps a misunderstanding.

[kramnnim]

At least with Amererican Classic, if you go from Shimano to Campy, "re-dishing" is required.

I was planning to do this freehub body swap later today...how much off center does the wheel end up being? .75mm? This seems to show that the Campy body is 1.5mm wider? http://www.amclassic.com/documents/help/2010/17mm_Rear_Hub_Overhaul.pdf

[woolly]

All the hubs I have converted, using the manufacturers freehub, not some aftermarket thing, has resulted in a dished wheel, no re-dish required(DT, Campagnolo, Powertap, Zipp....). Campagnolo cogset stacks are wider than shimano but the maker, if designed correctly, takes that into account.

I've switched my DT240 hub back & forth without the need to change the dish. Super, super easy to swap the cassette body & end-caps. Now, some may say that the flange spacing on these hubs isn't optimal, and they may be right. But for swapping b/t Campy & Shimano, I can't think of any that are easier.

[ergott]

Alchemy, Tune, White Industries and American Classic all need the rim to be recentered when making the switch.

It's my opinion that this is better. If you use Shimano, you can have the right flange further from center making for a stronger wheel. Most people ride Shimano/Sram so when using the above mentioned hubs, you reap the benefits.

Most people do not switch between drivetrains. I don't know how many people use the same set of wheels on two different bikes, one having Campagnolo and the other having Shimano/Sram.

The recentering of a rim takes about 5 minutes to do so in the case of selling a wheel, it's not a big deal. The bigger deal is the cost of the freehub body. Tune's is prohibitively expensive.

[brians647]

...
The recentering of a rim takes about 5 minutes to do so in the case of selling a wheel, it's not a big deal. The bigger deal is the cost of the freehub body. Tune's is prohibitively expensive.

Speak for yourself. ;)

[Louis]

Part of the reason I ask is that I now have a Campy wheel on my DeRosa with a Campy drivetrain. I want to switch the drivetrain to Shimano and was pleasantly suprised to find out that Campy makes a 9-spd "sex change" freehub which I assume simply replaces the freehub that is currently on the wheel. If I swap that out I can understand having to adjust the r-der (it's going to be replaced by a Shimno r-der anyway) if the cassette moves a bit, but I assume that the position of the rim relative to the lock-nuts/end-caps will not change, hence no need to re-dish.

We'll see what happens when I do it. (Not today, I have to do my taxes.)

[CNY rider]

Alchemy, Tune, White Industries and American Classic all need the rim to be recentered when making the switch.

It's my opinion that this is better. If you use Shimano, you can have the right flange further from center making for a stronger wheel. Most people ride Shimano/Sram so when using the above mentioned hubs, you reap the benefits.

Most people do not switch between drivetrains. I don't know how many people use the same set of wheels on two different bikes, one having Campagnolo and the other having Shimano/Sram.

The recentering of a rim takes about 5 minutes to do so in the case of selling a wheel, it's not a big deal. The bigger deal is the cost of the freehub body. Tune's is prohibitively expensive.

I am asking out of ignorance:
The distances involved (fractions of a mm?) sound miniscule.
What would happen if you didn't re-dish?

[Gummee]

I am asking out of ignorance:
The distances involved (fractions of a mm?) sound miniscule.
What would happen if you didn't re-dish?
Functionally? Not a whole lot. Your wheels won't be quite lined up and you *may* have some brake drag.

I've had screwy wheels that were 4-5mm out of dish and ran em for a bit just fine. ...then I noticed it and re-dished em!

Its not technically a hard job, but the better you are at truing wheels, the faster it goes.

HTH

M

[kramnnim]

My problem with the AC wheels is that the nips are almost frozen to the spokes and start to round off before they break free.

[ergott]

I am asking out of ignorance:
The distances involved (fractions of a mm?) sound miniscule.
What would happen if you didn't re-dish?

It's about 1-1.5mm usually. How much of a problem it is depends on frame clearances and tire choice. I want my wheels centered regardless.

Eric

[martinrjensen]

I wish I could tell you. All I know is that it required it, and I did it. I did it in (1/2 full turn) increments. It wasn't too bad. I was planning to do this freehub body swap later today...how much off center does the wheel end up being? .75mm? This seems to show that the Campy body is 1.5mm wider? http://www.amclassic.com/documents/help/2010/17mm_Rear_Hub_Overhaul.pdf