Sram crank/bb stand...
 

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[Closed] Sram crank/bb standard confusion

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Looking at a bike specced with a SRAM X1 Carbon Dub boost crankset, which I think is some kind of OEM thing. Chances are it will be 175, and I'll need to swap in a 170mm of some sort. Carbon dub stuff seems a bit spendy.

It's a PF92 frame - so presumably I'll need either another dub crankset or a new BB as well. Will I be able to swap in XTR/XT with an m8000 BB and run it with the SRAM GX stuff out back?

Anyone know of any other decent light crank options I should be considering?


 
Posted : 11/06/2019 8:40 am
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Yeah - dub is a 29mm axle, so any other non-Dub crank will need a different BB.

Shimano cranks are a 24mm axle, so you'll need a PF92 BB- plenty of those about, although decent ones (like Hope) are spendy I found the cheaper ones with plastic cups wear pretty fast. But yes, it'll work fine with the SRAM bits out back, as long as the chainring plays OK with 12 speed.

Raceface do light carbon cranks, but I'd avoid them unless you want to go through warranty pains, and again you're buying a new BB.

Flog the X1 Carbons and replace with a Descendant or Stylo Carbon

https://www.bike-components.de/en/s/?filterCategoryPath=60050127&sort=price_asc&keywords=dub%20crank


 
Posted : 11/06/2019 8:59 am
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Cheers - is there any reason I should steer clear of any of the older sram crank standards (GXP?). Is Dub any good/worth keeping?


 
Posted : 11/06/2019 9:20 am
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GXP is OK but can be a bit creaky.


 
Posted : 11/06/2019 9:23 am
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I would ask the shop you are buying from to swap out with a crank of the length you want, they might do you a good price. DUB actually makes reasonable sense as a standard, I just fitted a dub crank on a pf92 on a bike I am building.

I hadn't originally intended to though, but with sram axs coming out during the build, I was tempted by the bling, I do therefore have an unused hope pf92 24mm BB I want to sell if that's the direction you want to go in.


 
Posted : 11/06/2019 9:39 am
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The shop in question is having bother getting hold of anything suitable at the moment, but I may go down the anti-bling route and get a cheaper crank for now and upgrade if I see a bargain out there.

Anyone interested in a brand new X1 carbon 175mm crank with a 34t chainring? 🙂


 
Posted : 11/06/2019 10:01 am
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The

TRUVATIV CRANK DESCENDANT CARBON EAGLE DUB 12S 170 W DIRECTMOUNT 32T X-SYNC 2 CHAINRING BLACK (DUB CUPS/BEARINGS NOT INCLUDED)

Is in stock in the UK at the moment. Same crank, different stickers.


 
Posted : 11/06/2019 10:18 am
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Thanks Ben. Looking it up, doesn't seem to be a huge weight differential between that and GX anyhow.


 
Posted : 11/06/2019 10:27 am
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Surprised at that, X1 sits somewhere above GX but well below X01 in SRAM land but is 100% OE and not retail. I thought they’d dropped it tbh, although I admit I’ve not been paying much attention.

SRAM carbon cranks are usually somewhere between quite and silly light and have a much better reputation than RF’s for the arm and spindle staying stuck together. (I like RF’s alloy cranks). They’re expensive, which is a good reason not to buy in the first place, but less so if it’s already spec on a whole build. I’d be inclined to keep them at least until the first BB fail which could be some time. Once you want to change then BB92 is what you want for 24mm Shimano fit and as above get something with metal cups not plastic.


 
Posted : 11/06/2019 10:37 am
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OK, while I'm here...here's a stupid question...

If I have a boost crankset, do I actually need a separate boost-specific chainring, or has the 3mm offset already been provided by the crankset?


 
Posted : 11/06/2019 10:39 am
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Its all in the chainring (at least in the latest SRAM cranks).

FWIW I would ask the shop to get in the Descendants. Desc./X1/Stylo Carbon are the best cranks for the money you can get in my opinion. You need to spend a shed load more to get anything thats as reliable and significantly lighter.


 
Posted : 11/06/2019 10:51 am
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OK - so boost/non-boost SRAM cranks are basically identical in chainline terms? 🙂


 
Posted : 11/06/2019 10:58 am
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New direct mount crank arms are yes. Its all in the chainring - you buy a 3mm offset for Boost, 6 for non boost.


 
Posted : 11/06/2019 11:11 am
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Cheers!


 
Posted : 11/06/2019 11:13 am

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