rear hub spacing 150mm vs 148mm - what is 2mm?

[d_douglas]

Hello all,

I have asked about 150mm hubs in the past, but this has a different spin. There seems to be many 150mm DH type hubs out there in the world, some at ridiculously cheap prices. The current standard MTB hub spacing is 148mm Boost.

I know I am oversimplifying this, but if there is just 2mm difference in the axle length, is it not possible to file down each end cap by 1mm and use one of these nice 150mm hubs on a Boost frame?

[EB]

TL;DR: No.

Longer version: Cassette and brake rotor mount will end up in the wrong places.

[Sarhog]

Surly seems to make 142mm and 148mm wheels work on the same frame. Google “gnot boost”.

[d_douglas]

Originally Posted by Sarhog

Surly seems to make 142mm and 148mm wheels work on the same frame. Google “gnot boost”.

That is what I figured, but assuming that a wheels is symmetrical within the dropout and axis of the frame, why don’t brake rotors line up to within 1mm accuracy as well? Ok, I won’t pursue if it is t possible

There’s a 150mm DT350 hub in new condition for $100 locally, this is why I am asking

[Sarhog]

Originally Posted by d_douglas

That is what I figured, but assuming that a wheels is symmetrical within the dropout and axis of the frame, why don’t brake rotors line up to within 1mm accuracy as well? Ok, I won’t pursue if it is t possible

There’s a 150mm DT350 hub in new condition for $100 locally, this is why I am asking

I’ve no personal experience with this, I am just aware that they do it.

[EB]

Originally Posted by Sarhog

I’ve no personal experience with this, I am just aware that they do it.

I don’t think these are equivalent to what you want to do. The boost standard just moved the freehub outboard by 6mm, and the cassette and flanges along with it.

150mm is an old DH hub standard - it’s not the same as a 148mm hub plus 2mm and I’m not certain in particular that the cassette would land in the right place. But if you have a lathe and 1 hundred extra bucks nothing is stopping you from trying!

Incidentally newer DH hubs are 157mm, and there is also a 157mm version of Boost with different flanges than the 157 DH standard called Super Boost. We can all blame Chris Cocalis for the existence of the latter.

[d_douglas]

That is the reason I didn’t buy a knolly - the sizing is too weird for me!

[tristan]

A bit of history: Mountain bike hubs went from 135mm to 142mm in OLD (over locknut). This was achieved by using the same hub shell and changing the endcaps. The 142x12mm endcaps are 7mm wider, and 3.5mm on each side sits on a small shelf inside the frame to help locate the wheel and make installing the thru-axle easier.

We then went from 142x12 to 148x12. This was achieved by widening the hub shell by 6mm, and using the same endcaps.

A 150mm hub can be converted to 157mm in the same way as a 135mm can be converted to 142mm.

If you put a 150mm rear hub into a 148mm frame the disc rotor and cassette would both hit the frame and bind.

Many modern good quality use interchangeable endcaps to fit a wide range of frame 'standards'. The Dial hub website is a good example where a Boost hub can be converted to different widths between 135 and 148mm simply by changing endcaps:
https://dial.bike/dialarcnu/#el-46ef030d

Some extra reading on hub 'standards'
https://www.wheelworks.co.nz/hub-wid...diameter-list/

[RudAwkning]

Originally Posted by d_douglas

That is what I figured, but assuming that a wheels is symmetrical within the dropout and axis of the frame, why don’t brake rotors line up to within 1mm accuracy as well? Ok, I won’t pursue if it is t possible

There’s a 150mm DT350 hub in new condition for $100 locally, this is why I am asking

150mm DH hubs run flush to the dropout faces whereas boost dropouts are recessed. So as other folks have mentioned, cassette and rotor will end up in the wrong places.

If the hub is new and the internals are 36t or 54t, it might be worth buying the hub just for the freehub body and star ratchets

[Nomadmax]

Bikes today are a straight up minefield for nearly everyone over 60.