School me on cranks and BBs

[sethschmautz]

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

[XXX-er]

Aeffect

[radam]

+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.

[rideit]

Yes, Aeffect is 24mm.

[toast2266]

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.

[Dantheman]

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.

You can buy the self-extracting bolt aftermarket for under $10.

[Ted Striker]

While race face make great cranks, their bottom brackets aren't.

[El Chupacabra]

X-whatever on the Aeffect -- 24mm spindle that will fit your existing Shimano BB.

If your BB is worn out too, then perhaps consider a SRAM direct mount crank + BB.

[XXX-er]

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 .

Hold the bike up in the air by its cranks, tap on spindle end with a hammer & drift they came lose pretty easy

[jm2e]

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.

[Toddball]

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?

[sethschmautz]

Buy my old XTR m985 crank for cheap?

Sent from my SM-N970U using Tapatalk

[jm2e]

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?

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.

[XXX-er]

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.

No way to tell now but I am willing to bet it was a great power meter until it tore itself apart because the fasteners were loose

[bagtagley]

Another Aeffect w/ Shimano BB vote.

[Toddball]

No way to tell now but I am willing to bet it was a great power meter until it tore itself apart because the fasteners were loose

I miss it already!

Another Aeffect w/ Shimano BB vote.

Ordered this combo, thanks.

[EWG]

No way to tell now but I am willing to bet it was a great power meter until it tore itself apart because the fasteners were loose

Has to be. The only way that happens is if one of the chainring bolts was super loose or popped off entirely.

[sethschmautz]

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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[El Chupacabra]

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...

[sethschmautz]

Boost (148) rear end.

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[jm2e]

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...

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!