Unable to secure rear wheel


New Member
I'm trying to repair an old bike that is missing several pieces and I'm having trouble securing the rear wheel.

The rear wheel is missing one of the nuts that secures it to the frame. I think the existing nut is an M10 (as advised by Halfords). However, after buying a new M10 nut I am unable to tread it onto the rear axle/bolt (not sure whats it's called). The rear axel isn't cylindrical as I would expect. It has two straight edges either side, like an oblong (see attached). Maybe this is why the nut wont thread on? But then why does the existing nut thread? I've attached a picture of the new (left) and existing (right) nuts, are they different?

Any help/advice on this would be much appreciated.



Legendary Member
Accra, Ghana
I should never take anything anyone employed by Halfords says as gospel :smile:

I should take it down to your local bike shop for them to find the correct nut, as a last desperate option take it to Halfords :ohmy:

Big John

Agree with Michael. Maybe that axle has been used to replace an old broken one but my guess is it's not an original from that bike. That said, it can still be used providing you find a nut and washer to fit it. The fact it's got thread on it means it's round so don't be put off by the flats on it. Most folks on here have got a bagful of miscellaneous nuts and bolts to fit almost anything but if you haven't then definitely, like Cyclops says, visit your proper LBS for assistance. He'll have stuff to fit and it shouldn't cost a fortune.
From Sheldon Brown:

The axle threading of most SRAM internal-gear hubs is unusual, 10.5mm x 26 TPI, but close enough to that of many Sturmey-Archer hubs (13/32 x 26 TPI) that Sturmey-Archer axle nuts are usable in a pinch.

My understanding is SRAM and Sachs use the same thread size, but the SA nuts are easier to come by, so may be worth a try.


Ride It Like You Stole It!
South Manchester
I always thought those flats on the axle were to present those to the top and bottom of a horizontal drop out (and the special washer 'enforces' that) to minimize wear to the threads from the drop outs.
Nope, just to keep the washer in place - stops it spinning. Proper bike shop I feel for the correct thread. Unlikely to be metric M10.


New Member
Hi all. Thank you so much for your responses. I really appreciate your help.

I will have another Google with this new information and if all else fails then I will take it into a local bike shop.
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