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Thread: School me on cranks and BBs
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11-18-2019, 11:50 AM #1
School me on cranks and BBs
I have an older XTR M980 crank that I've been running as a 1x crank for a number of years and I think I'm going to replace it with a direct mount style crank. I'm currently looking at the Raceface Turbine 30 as it seems like it's relatively light and has a direct mount chainring - the latter of which will allow me to run smaller than 30t chainrings. I'm on a Hightower 1 with a 73mm threaded BB shell, and I'm pretty sure my current BB won't work (XTR SM-BB93) due to spindle size. Do I need the RF Cinch BSA30 or something else? I'm having a tough time understanding exactly what I need, as it seems like some external BBs don't play well with cranks intended for a PF BB.
Any other cranks or BBs that I should consider that will allow for a smaller chainring (28t or 26t)? Price point is around $150-200 and I don't mind buying a used crank. I'd like to keep weight in the same ballpark as the M985 (~520g for the arms and spindle).
Thanks!
Seth
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11-18-2019, 12:24 PM #2Registered User
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Aeffect
Lee Lau - xxx-er is the laziest Asian canuck I know
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11-18-2019, 12:36 PM #3
+1 for Aeffect. Have run them on several bikes. Just make sure you get the version with a self-extracting bolt. I somehow ended up with one that does not have the self-extracting bolt and having to bust out the crank puller when needed is kind of annoying. Weight is just under 600 grams for arms+spindle and I think you can keep rocking your XTR bb if you want. Oh and they are cheap so you can just go ahead and buy new.
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11-18-2019, 12:38 PM #4
Yes, Aeffect is 24mm.
Forum Cross Pollinator, gratuitously strident
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11-18-2019, 12:47 PM #5
What length are you looking for? I think I have some Raceface Sixc cranks that I could sell you that'd fit your budget. I'd just need to check and see what spindle and BB I have for them.
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11-18-2019, 12:51 PM #6
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11-18-2019, 12:58 PM #7
While race face make great cranks, their bottom brackets aren't.
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11-18-2019, 01:01 PM #8
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11-18-2019, 01:03 PM #9Registered User
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11-18-2019, 01:35 PM #10
Crank puller? Fuck that. What are you selling, square taper?
Buy Toast's cranks. Maybe he's even got a BB for you.
Other option is to get a Sram GXP X0 crankset for about $200 bucks and get a GXP threaded BB for another $30.However many are in a shit ton.
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11-18-2019, 03:41 PM #11
On this subject, I have an old Surly Karate Monkey with a square-taper BB, 73mm BB shell (or whatever the MTB standard is), and a Shimano Hollowtech (II?) crankset. The BB was getting a bit clicky, which was cool because the click pitch + volume was proportional to torque on crank, so it was like getting a free power meter. On this morning's commute, however, I managed to destroy the chainring and crank spider in the middle of a busy intersection.
I have a number of spare parts, which are not compatible with each other:
3x Race Face direct mount chainrings
SRAM Rival crankset with 68mm spindle (or whatever; spindle not long enough for BB shell) and 40t chainring
SRAM GXP BB (fits in BB shell, which is how I found out the crank spindle is too short)
Is there a crankset I could buy that works with RaceFace direct mount rings AND GXP BB? Or should I buy a SRAM crankset + ring? Or what?
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11-18-2019, 09:44 PM #12
Buy my old XTR m985 crank for cheap?
Sent from my SM-N970U using Tapatalk
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11-18-2019, 10:20 PM #13
Probably cheapest to get a RaceFace Affect Cinch crankest and bottom bracket that will work with your chainrings. Or get a Sram X9 GXP crankeset and buy new chainrings. Just make sure you don't get a BB30 version.
Edit: or buy that XTR for cheap. Those things are light as ballz.However many are in a shit ton.
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11-19-2019, 10:01 AM #14Registered User
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11-19-2019, 11:11 AM #15yelgatgab
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Another Aeffect w/ Shimano BB vote.
Remind me. We'll send him a red cap and a Speedo.
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11-19-2019, 02:39 PM #16
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11-19-2019, 05:47 PM #17
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11-26-2019, 10:02 AM #18
Alright, here's my follow-up question. I'm picking up Toast's raceface Sixc crank and BB (thanks Toast!) tonight and need to pair it with the right chainring. I have a standard 68/73mm threaded BB shell on my Hightower v1 with a 50mm chainline. Do I need the chainring with 3mm or 6mm offset?
Thanks in advance.
Seth
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11-26-2019, 10:14 AM #19
Boost or non-boost frame?
Edit to clarify: boost frame with boost-appropriate crank = 3mm.
Non-boost frame with non-boost crank = 6mm.
I don't know if there is a difference between boost and non-boost Race Face cranks. Being a direct mount chainring, I wouldn't think so, but...
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11-26-2019, 11:24 AM #20
Boost (148) rear end.
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11-26-2019, 08:59 PM #21
I'd love the experts to chime in on this: My vague understanding is that there is zero difference between a Boost and a Non-Boost Crankset (assuming we stick to talking about spiderless chianrings). The difference is the offset of the chainring, which they sell with specific offsets fitting each of the spiderless mounts. I assume it would be a different story with spidered (ie Shimano and cheap) cranksets. But maybe I'm wrong. ............ Then there's Super-Boost/157Trail as well as good olde DH .......
Please, someone, help us see the light!However many are in a shit ton.
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