I have a pair of Titanium forks that take a 9mm x 135mm qr front wheel with front disc spacing, I’d like to be able to run a 10mm x 135mm qr rear wheel (with the disc spaced out by 5mm). I probably wouldn’t do it myself but instead find a framebuilder or similar to do it.

How bad an idea is this?

Would I also be able to run a 9mm axle in the 10mm dropout without too much issue?

Thanks in advance for any help!

I’d probably use a reamer (but never tried this on Ti);

https://www.ebay.co.uk/p/BQLZR-HSS-Adjustable-Size-Range-9-25mm-10mm-Hand-Reamer-Metal-Hole-Cutting-Tool-Replacing-Part/1570281644

I’d be worried about the 9mm axle moving round under heavy loads though so wouldn’t want to switch back – I’d not trust a QR to keep it in place.

I did this on some front forks before I realised the difference between 9mm QR and 10mm threaded axles, oops!

Took just a wee bit of filing and the 10mm wheel slotted in fine, still takes a wee bit of a dunt on the top of the wheel to get it back out. Haven’t tried a 9mm wheel in the drops yet but it’s only rim brakes so I’m sure a Shimano QR should do the job fine.

135mm front spacing. Is that fat bike?

Could it be better to get a custom axle made up? Know anyone with a lathe?

Haven’t tried a 9mm wheel in the drops yet but it’s only rim brakes so I’m sure a Shimano QR should do the job fine.

Please let us all know how you get on with that.

You won’t be able to drill or use a reamer on it and produce a good result as it isn’t a hole, it’s a slot so won’t cut evenly. A die grinder, Dremel or round file and some skill would be the way to go but make sure material is removed evenly and from the right place.

9mm axle in a 10mm dropout is likely to move around and be a pain especially keeping a disc aligned.

I’d like to be able to run a 10mm x 135mm qr rear wheel

Obvious question is obvious but why would you like to do this? Surely possibly ruining a nice (enough to consider to bodging it at least) ti fork really isn’t worth the trouble if it’s just so you don’t need a new hub?

I have a rear wheel I can use and not only would it save me getting a front wheel but i could run a singlespeed wheel at the front for if my freehub died in the middle of nowhere. It’s probably not necessary though and I’d only do it if there was no risk to the forks as they are mighty expensive.

I have a rear wheel I can use

Is it possible to set that up for a 10mm through axle and then either put a 2 pairs of flat spots on that so it’s 9mm at the appropriate point or get a 9mm axle and a length of 10mm x 0.5mm stainless tube and shim the centre to support the wheel (eg ebay item 282690502982 but you’ll only want a dinky bit), the fork dropouts should hold the shim in place if it’s correct and full huh width.

Should work fine, not risk your fork or make it unsuitable for 9mm axles in the future.
Assuming your rear is setup the same you can swap wheels over should you ever need and it’ll cost about £10-20 to get the thru axle + tube (but i imagine you’ll get an off cut from somewhere) and give it a go.

surely the dishing would be all wrong so your plan of having an emergency rear wheel would need to you re-dish on the trail unless it was a symmetric rear build?

Assuming it’s a QR slot drop out then just file some flats on the hub axle so it can slot into the 9mm slot but then rotated 90 degrees will still be snug in the 10mm slot.

Failing that convert the hub, if you can, to take a 10mm QR and then use a bit of 10mm OD, 0.5mm wall (https://www.ebay.co.uk/itm/Stainless-steel-tube-10-mm-o-d-x-0-5-mm-wall-type-316L-x-1-metre-Long-/282690502982) tube to make a 9mm QR fit snug in the hub.

Bloody hell – we both pretty much gave exactly the same solutions even down to the same ebay link for tube!

There’s something about great minds I’m sure – not sure quite how it applies to me mind.

no me. Feeling particularly frazzled today (and that was before I have been in work 11 hours so far 🙁 )