I need to get a 15mm hub without end caps to fit a 12mm fork whose dropouts look like this (note that the black part has a lip):

fork 12mm dropout

When my SON dynamo's bearings went out on a cycling tour here in Africa, I bought a 15x100mm hub + 12mm adapter (tube, not end caps). The new hub won't fit under that hub location lip.

In Africa, the only options available are either 15mm hubs with 12mm end caps or QR hubs. Buying from US/Europe will be very expensive and time consuming.

Here are some options in order of cost:

  1. Grind down the 15x100mm hub to be 15x98mm and find spacers that will fit under the lip.

  2. Buy a 9mm quick-release hub, and find a way to mate it to the 12mm thru-axle dropouts. As far as I know, adapters can step a hub's axle diameter down (12mm>QR) but not up (QR>12mm).

  3. Buy a 15mm hub with 12mm end caps online. This will only work if the actual hub is <98mm and the very end of the end cap will fit under the lip. Similar to the idea in #1 but factory quality.

  4. Buy a 12x100mm hub from Germany and spend an extra $100-300 in shipping + accomodation while waiting for it.

#3 seems like the best. So in short, do hub end caps generally work around that lip? And if not, which are good alternatives?

2 Answers 2


A 100x15mm with conversion endcaps for 100x12 should act like a 100x12 hub in every way, and shouldn't have any problem with the lip.

Unless it's looseball, you could also look into the possibility of having someone with a lathe make you 12mm endcaps or an axle for the 15mm hub you bought.

Again depending on the design of the 15mm hub, you could look at relieving material off the endcaps or lockouts so that they clear the fork lips.

There's also the possibility of grinding the lips.

  • It's a SRAM 716, which has cartridge bearings. No end caps that I know of. As far as grinding goes, I'd grind off my own lips before I ground down the ones on my fork. People at the hardware store had never heard of a lathe. Went with grinding the hub. Commented May 26, 2023 at 20:13

Here's how to get a 15mm through-axle hub to work on a 12mm through-axle fork in a third-world country:

  1. Already have the 15mm to 12mm universal adaptor tube, and a 12mm through-axle.

  2. Score the hub where it hits the lip on the fork.

Score marks on front hub

  1. Find a grinder at an auto shop and grind down to where the scored line is. DON'T CONTINUOUSLY GRIND THE HUB! The build up of heat will damage the seals, so run it under water often.

  2. Find spacers such as lock washers that both slide onto your axle and fit inside the lip. Take the axle with you and ask everywhere because random things will probably work.

15mm Hub and spacers on 12mm fork

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