Question on Mavic XM719 rim
 

Hello:

Have two bikes: one with disc brakes and the other with rim brakes.
When I buy/build wheels, want to combine hubs for disc brakes with rims for rim-brakes so that can use wheels with either bike.

Q1: Is this advisable?

Considering Mavic XM719 rim.

Q2: Are there any differences between the rim-brake and disc-brake versions of this rim? Beyond machining of the braking surface.

There's no reason you shouldn't build disc wheels with rims that can be used with caliper brakes. Until makers started producing disc specific rims, all dich wheels were built with rims that had brake tracks.

This isn't with 100% authority, but I believe that the two rims are the same except for the finishing of the brake track.

Here are the images from Mavic's site. Do they look identical or different?

Rim brake
http://bikeforums.net/attachment.php...hmentid=350216

Disc brake
http://bikeforums.net/attachment.php...hmentid=350217

Those two rims do have different profiles. The disc brake one does not have a usable brake path, if you look, its angled inwards unlike the rim brake rim that has a vertical profile for the brake path.

So no, the disc brake only rim can't be used with caliper/canti/v-brake pads due to the lack of the vertical brake path profile.

However there is no reason at all not to use the rim brake rims with a disc brake hub so you can use the wheelset on either types of brakes.

Do you trust internet pictures?

It doesn't matter either way.

The OPs question was whether there was any reason not to use a rim with a brake track on a disc brake wheel, not the other way around.

The answer to that is no, the existence of a brake track won't in any affect the wheels performance, whether used or not. Of course going the other way and using a disc specific rim on a non-brake hub, leaves no good way to arrage brakes, but I gather the OP could have figured that out for himself.

BTW- a rim without a brake track may be lighter than it's most similar brake track rim, since it doesn't have to have 1mm of sacrificial material in the wear zone. But it's not exactly an earthshaking difference.

Nothing wrong with building rim brake rims onto disc hubs - slightly heavier but more flexible swap-wise wheel set is the result.

ERD is the same for XM 719 and XM 719 Disc.

=8-)

Remember though, the OP wants a set of wheels that can be used on rim brake or disc brake equipped bike and asked if the 2 rims pictured were the same. I pointed out that the disc brake rim pictured has MUCH less flat surface that would be used for rim brakes so I would say that rim could not be easily used with rim brake. I would just go with the rim brake rims on a disc brake hub. I have a set of wheels like that on my mountain bike, disc brake hubs with rim brake rims.

Thanks guys.

FBinNY, it was really nice to meet you on Saturday!

Same here, and also to Andrew S., Sureal, and the others who stopped by.