I’m Up grading my square taper set up and would like to go lighter and more modern.
I’ve removed the old one and it is 73mm. But I’m not sure what length I would need.
The bike is a trek marlin ss. 2011. (The one with the bad adjustable dropouts)
I have installed the new dropout hanger so I can go geared. I’m looking to go 1×9 and want something 2nd hand that I know will work, but I want to be sure of the axel length.
I’ve never used hollow tech, can you adjust the of the chain ring to clear the rear stays or bring it closer for the best chain line. ( might be a numpty question, sorry)
Stoddy

Have you removed the old BB? Are you going from square taper to external bearings?

If so, axle width is almost always 68/73mm (adjustable with plastic spacers on the BB). Just don’t buy a DH chainset by mistake and you’ll be OK.

I’d look for a Shimano SLX if it were me, they’re light and durable and cheap – and easy to fit.

Yep old one is out fine it’s 73mm, I’ve never use the external but it seems the way to go.
I was just concerned with the chain line.

There is some adjustment with external by altering the placement of the spacer rings which sit between the bb and the frame.

Ok guys thanks.

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