I recently bought some Roval SLX 24's from eBay. I made a pretty silly error and didn't check whether they were rim or disc brakes. I need them to be disc brakes.

Should they be rim brakes, will I be able to convert them to disc brakes for my Cannondale 2015 CAADX Sora?

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    We've all done something similar, (or will) so treat it as a learning experience. Or consider it a chance to buy a rim brake frame and assemble another bike on the Roval wheels.... N+1 and all that. – Criggie Mar 26 '19 at 12:25

The hub for a disc brake wheel has the mounting for the brake rotor machined into the left side, and has shorter spokes that side to make room for the brake.

If the eBay wheels are for rim brakes, they won’t have these disc mount features out the box. If the spoke counts match and are sufficient, you could theoretically rebuild the rims onto disc specific hubs, but at best you would only be able to reuse half the spokes, quite possibly you’d need to replace the hubs and all the spokes.

It’s not that this can’t be done, but it would probably be less economical in time and money than paying return postage or fees for listing the wheels again on eBay yourself to then buy the right set. You would also have to sell the unwanted hubs and spokes to recover the money sunk into those. It would certainly be more hassle!

Great point from @Rider_X that disc wheels can require higher spoke counts, so that may take the whole exercise off the table anyway. Rim version of these wheels are 20 spoke front, 24 spoke rear, while the disc version is 24 front, 24 rear. In general terms, not having enough spokes on the disc (or any) wheel would be a bad idea.

  • I figured this might be the answer. Shall see when they turn up later this week. – Jarede Mar 26 '19 at 11:28
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    @Jarede contact the seller immediately - see if you can stop them being shipped and cancel the transaction. You may have to wear a restocking fee or the auction success fee... – Criggie Mar 26 '19 at 12:26
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    Disc rims wheels usually have a higher spoke count and often a different spike pattern (especially the front wheel). So a wheel rebuilt isn’t likely a great option. – Rider_X Mar 26 '19 at 13:43
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    @Nelson It's maturity to bear the cost of one's own mistakes. – Craig McQueen Mar 26 '19 at 22:57
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    If the OP still wants to return it, then there is nothing mature about wasting money. If the advice is simply keep the product, then my advice isn't relevant. – Nelson Mar 27 '19 at 12:06

You have to change the hubs which pretty much makes the exercise superfluous. Sell them and buy the correct wheels.

  • This adds nothing to Swifty's answer. – David Richerby Mar 28 '19 at 10:12

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