BB30 vs GXP

[Quagga]

Double post. Sorry

Edited July 17, 2020 by Quagga

[DieselnDust]

Sorry. I have not been clear.

 

We want to take gxp crank off a spez and fit dub.

Can we use current chainring

 

Then we thought going bb30 will chainring work on that.

 

Bottom line is. Friend has gxp on boost spez 2018.

Can he go dub without a new chainring or even bb30?

He wants to keep chainring saving him R1k eish

 

 

Ok thanks. Can work with that but a few more questions.

 

What model Specialized is it?

Is the BB shell PF30 73 i.e. 46mm internal diameter and 73mm wide 

Or is it a BSA threaded BB (36mmx24tpi)

 

I've squizzed through the Specialized website to see which model of bike came with a GXP cranks but most seem to already have had DUB fitted

[Quagga]

Ok thanks. Can work with that but a few more questions.

 

What model Specialized is it?

Is the BB shell PF30 73 i.e. 46mm internal diameter and 73mm wide

Or is it a BSA threaded BB (36mmx24tpi)

 

I've squizzed through the Specialized website to see which model of bike came with a GXP cranks but most seem to already have had DUB fitted

The 2018 gold/red one. Still has gxp. All the rest seem to have dub

 

So we to fit dub and I wanted to see if the current chainring would work.

We need new dub screw type bb.

 

Buddy wanted to if he gets the crank. Are we looking at another chainring and if so what offset. Then we can see if we have one laying around.

 

So I thought. If I can see spindle length of gxp and compere to dub we can work out the chainring offsets

[JA-Q001]

GXP to DUB should be a straight swop of chain Chainring. Just make sure of one thing ( that I havent checked before) the DUB cranks may have the new 8bolt (I think its 8) interface and the older GXP had 3 bolt. But I think you may be lucky and the normal DUB cranks for mtb is still 3 bolt. (Road changed almost all DUB cranks to 8 bolt)

 

If the frame takes a threaded BB then a short axle BB30 wont fit. This will be an axle length of about 86mm-90mm crank face to end. Long axle BB 30 will be exactly the same length as DUB.

[DieselnDust]

JA-Q DUB is not available on SRAM Road yet.

DUB mtb cranks are still 3 bolt.
quarq mtb is 8 bolt like the quarq Road.

 

You're spot on with everything else

Quagga right so it's an Epic right?
If yes then it's got a 73mm BSA BB shell.
you'll need the DUB BSA threaded BB.
You will need spacers to get the chain line right. I'm not sure if those are included in the BB package
the DUB Crank won't care about the offset. You can use the same 3 bolt direct mount chainring from the GXP Crank. The chainring mounting interface is the same for GXP and 30mm cranks and DUB. I've swapped chianrongs from gxp to 30mm and back with no issues.
You will need the 3mm offset chainring.

 

If you want to go BB30 its as JA-Q states, long axle BB30 but I'm not aware of CCS ever importing these as I made the mistake of buying a BB30 XX1 crank only to discover the ale was too short by 6mm.

Edited July 18, 2020 by DieselnDust

[Quagga]

Thanks very much hubbers.

 

We gonna go for DUB and and I now what spacers you are talking about you can fit a 1.5 or 2.5 mm space to get chainline correct and then adjust tension on the left side