Sram BB help

mr.b-campag
mr.b-campag Posts: 414
in Workshop
Looking to put a shorter crank on the bike I bought recently - one of these:

https://www.bikes.org.uk/scott-addict-r15-2011-road-bike/

It came with a 172.5mm chainset and I've bought a 167.5mm. Only thing is the latter has outboard bearings on it and the bike doesn't. Obv. I won't be able to use that BB with the outboard bearings, but can I swap them for what is on the bike (press fit) and use the chainset I've bought?

This is the new chainset:




And this is the existing one:




To my untrained eye they look like the same GPX chainset. Can I (or 'my' mechanic) fit this 'new' chainset on the bike?

Thanks


Comments

  • me-109
    me-109 Posts: 1,915
    If the old chainset is GXP and not BB30, then you shouldn't have to touch the BB itself. Just pull the old chainset and insert the replacement.
  • mr.b-campag
    mr.b-campag Posts: 414
    Thanks me-109 - any way of knowing without removing the one that's in there atm (which I almost certainly don't have the tools for)?
  • whyamihere
    whyamihere Posts: 7,716
    It's almost certainly GXP. GXP has the bolt on the non-drive side, BB30 and DUB have it on the drive side. Removal is just with an 8mm hex key by the way, they have a self extractor built in.
  • mr.b-campag
    mr.b-campag Posts: 414
    edited November 2023
    whyamihere said:

    It's almost certainly GXP. GXP has the bolt on the non-drive side, BB30 and DUB have it on the drive side. Removal is just with an 8mm hex key by the way, they have a self extractor built in.

    Ah ok thanks, an 8mm hex key I should be able to manage. Assuming it is a GXP does the 'new' bb with the outboard bearings just slide off (I guess I have to remove the spider on the drive side)?
  • me-109
    me-109 Posts: 1,915
    Spider removal not required. Use the smaller hex key/bolt not the larger - that's what the small one presses against. Standard right hand thread IIRC - anticlockwise to loosen. You might need a tapping stick to get the axle moving out of the frame. If the threaded BB doesn't just slip off you might need to lever against the inside if the spider or hold the BB and tap the end of the axle. Don't hold the chainset too far off the ground if you do that.
  • trevor.hall12
    trevor.hall12 Posts: 496
    mr.b-campag said:

    whyamihere said:

    It's almost certainly GXP. GXP has the bolt on the non-drive side, BB30 and DUB have it on the drive side. Removal is just with an 8mm hex key by the way, they have a self extractor built in.

    Ah ok thanks, an 8mm hex key I should be able to manage. Assuming it is a GXP does the 'new' bb with the outboard bearings just slide off (I guess I have to remove the spider on the drive side)?
    If its on properly you'll need more than a hex key ,never got 1 off without a 2ft breaker bar

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