Despite trying to search the forum and other web places I can’t quite figure out what’s what with hub widths at the back end.

My bike has come with the previously standard (now niche?) rear 9mm QR on what I thought was a 135mm width. It’s a SRAM 506, which according to SRAM is 145mm width linky. Confusingly my old 135mm wheels fit my frame.

As I want to upgrade my wheels, does this mean I can get away with 145mm hubs using the appropriate adapters to go with the 9mm QR’s?

This is all part of a grand and gradual upgrade plan, better wheels, better frame, better this that and the other…

your frame will be 135mm

Axle length and hub width are not the same thing. Your frame is likely to be 135mm wide. I don’t know of any bikes currently using a different width with a standard 9mm QR.

Wot he said. The axle is 145 to allow it to stick out a bit into the dropouts, but not all the way through otherwise the skewer wouldn’t hold it tight. The OLN (Over Lock Nuts) measurement will be 135 and should match the frame without any serious pushing or pulling.

Jimalmighty – Member

your frame will be 135mm

So why do the hubs, 145mm according to SRAM, fit into the same gap as my older ‘135mm’ wheels..

The rear dropout inner faces are 135mm apart. Each is ~7mm thick. So the outside faces are ~149mm apart. The flanges or locknuts on the hub are 135mm apart and sit in the frame, with 5mm of axle protruding into each 7mm of dropout. This allows the faces of the QR nuts to sit on the outside of the dropout and cinch up tight to hold it all in place.

The late, great Sheldon Brown wrote a lot of this stuff down and created a fantastic resource.

http://sheldonbrown.com/gloss_n-o.html#old

So I can forget about any thing describing itself as anything other than a 135mm then?