Shortening your cranks

[Donnyboy66]

As suspected the hope cranks didn't work even though the people at hope kept insisting they were compatible. but it didnt cost anything to try. so now I'm on the waiting list with North Shore Billet.

I see the cranks are available again from North Shore Billet. Hopefully you got what you wanted!

 

[Rawmance]

Was in contact to US and UK for shortening cranks but I thought maybe there is someone inside EU or even Finland. Found a leanbiker who has done shortenings for years. Followed the instuctions on here and now I have 150mm Atlas cranks on my Rocky Mountain. It's great. 182cm height, 84cm inside leg. Had 155mm FSA ISIS cranks on the previous bike and I definitely like the 150mm more. It's really necessary for Powerplay as the power delivery is so lazy compared to Bosch gen4 that you really don't want to stop pedaling. Just feels nicer to pedal even without the massive clearance benefit. 165mm original cranks on A50.

Cost total was 500€ for the Cranks, new BB, 30mm lockring, drilling and install.

Drilling cost and postage inside Finland 100€.

Contact detail for Teppo for Finnish and possibly other European customers so you can ship back and forth without taxes. [email protected]

 

[skewered]

I machined some Turbine cranks down to 150.5 over the weekend. Haven't ridden them yet as I am still waiting on some of the parts for the exchange. They turned out nice though and I added a curved chamfer on both the front and back to hopefully skip off the rocks better!

 

[philbwy]

I see the cranks are available again from North Shore Billet. Hopefully you got what you wanted!

Today was the day. Installed the North Shore Billet 155 cranks. Went for a short ride. Raised my seat post 15mm. Felt a little different for about 2 minutes and then felt as usual. I will decide if I need to change the rise on my bars after I go for some longer rides. Pedalled through some rocks and lightly scraped a pedal once where I normally would have hit it hard. So far so good.

 

[EzRyder]

I reserved a NSB 155 with shorelines in the UK which i no longer need, get in touch with them if you want one without the long wait. My friend machined down a 175mm Atlas for me in the end, just need to fit it. Its prob about 148mm.

 

[Bad Mechanic]

Race Face has released a 160 Turbine crankset:

Race Face Turbine Crank | Alloy Mountain Bike Crankset |XC Trail All-Mountain |

The most trustworthy alloy crank on the trails, thirty years running. The Turbine delivers an incredibly stiff and responsive ride with uncompromised durability. Go ahead and get rowdy. Turbine has your back.

www.raceface.com

 

[cody311]

Race Face has released a 160 Turbine crankset:

Race Face Turbine Crank | Alloy Mountain Bike Crankset |XC Trail All-Mountain |

The most trustworthy alloy crank on the trails, thirty years running. The Turbine delivers an incredibly stiff and responsive ride with uncompromised durability. Go ahead and get rowdy. Turbine has your back.

www.raceface.com

52mm - 136 Spindle, 55.5mm - 143 Spindle No way these will work with those spindle lengths.

 

[Bad Mechanic]

52mm - 136 Spindle, 55.5mm - 143 Spindle No way these will work with those spindle lengths.

As with other Race Face cranks the spindle needs to be replaced:

Spare Parts Collection. MTB & eMTB Riding | Race Face

The Race Face Spare Parts Collection for MTB & bike maintenance. Find rebuild kits for pedals, cranksets & wheels. Choose decals, tubeless kits & more.

www.raceface.com

 

[cody311]

As with other Race Face cranks the spindle needs to be replaced:

Spare Parts Collection. MTB & eMTB Riding | Race Face

The Race Face Spare Parts Collection for MTB & bike maintenance. Find rebuild kits for pedals, cranksets & wheels. Choose decals, tubeless kits & more.

www.raceface.com

How does one replace the spindle? I feel like that would have been covered in depth if it was a possibility.

 

[Bad Mechanic]

How does one replace the spindle? I feel like that would have been covered in depth if it was a possibility.

It's easy. Just remove the old spindle using the self extracting crank arm bolt, then bolt on the new spindle.

 

[cody311]

It's easy. Just remove the old spindle using the self extending crank arm bolt, then bolt on the new spindle.

Self extending crank arm bolt?

 

[Bad Mechanic]

Self extending crank arm bolt?

Self extracting. Autocorrect.

 

[cody311]

Self extracting. Autocorrect.

Are you saying this tool?

Foundation Bike Crank Arm Extractor Tool | Jenson USA

Wrench it yourself with Foundation Bike Tools From pedal wrenches to repair stands Foundation Bike Tools offers a collection of quality tools that are essential to keeping your bike in top shape and ready for adventure. Foundation Bike Tools is here to give you an extra set of hands for basic...

www.jensonusa.com

 

[Bad Mechanic]

Are you saying this tool?

Foundation Bike Crank Arm Extractor Tool | Jenson USA

Wrench it yourself with Foundation Bike Tools From pedal wrenches to repair stands Foundation Bike Tools offers a collection of quality tools that are essential to keeping your bike in top shape and ready for adventure. Foundation Bike Tools is here to give you an extra set of hands for basic...

www.jensonusa.com

No. The Race Face cranks with a normal crank arm bolt on one side, and a self extracting crank arm bolt on the other side. When you loosen a self extracting crank arm bolt it removes the crank arm from the spindle.

 

[makeithappen]

I would like to add some information here as I have no doubt others are having this same issue.

I sent RM this question in regards to options for us:

"I am needing to downsize the 170mm cranks on this Power Play but I am having a difficult time finding the correct axle length within the Cinch lineup of options. I am under the impression that a 149.5mm length is required to accommodate the sprag clutch. With the offerings on the RaceFace website for Atlas cranks in 165mm length but only offering the 151mm axle length, can I just use a 1.5-2mm spacer here?

I am aware that I will need to also get the larger 30mm BB bearings and associated snap ring for the sprag clutch, is this available for purchase on the Rocky website for the 2022 models (the snap ring, I can get 30mm press fit without issue)? I can see a ton of part numbers on the Rocky site but so many of the purchase options do not have a photo so it is hard to understand exactly what it is I am purchasing."

Here was the response from Reed,

"Thanks for reaching out. You're on the right track. The 151mm Spindle length with a small spacer will work great with the spider assembly on the cranks. I'm afraid the 30mm Lockring is not available directly from our site though you can order it through your local Rocky Mountain dealer. The part number you'll need is 1347006. If you provide that to the shop they'll be able to get it ordered for you fairly quickly."


I am currently working with someone to maybe do a run of Atlas cranks drilled and tapped at 155 and 160mm. If there is any interest here, please reach out. I would like to do a run of 4-8 and gauge interest based around that initial investment. Looks like the most difficult part of this will be getting the correct snap ring but I bet an alternative could be found on McMaster or something. I will update here with more information.

Hey you have someone you know that can machine some atlas 175 to 155 ? thanks in advance. Also where in Colorado you from ? Im in Grand Jct

 

[makeithappen]

Over the past weeks ive been gathering information on how to shorten the cranks on Rocky Mountain Powerplay bikes. I hope this info helps some of you with this quite complicated task.

So in order to get shorter cranks than the stock 170's (or if you are lucky the 165) there are a couple of solutions, both involve getting either a RaceFace Atlas or Turbine crank set.

So to start with you either have one of 2 situations:
1. You already have the bigger 30mm axle cranks installed on your bike (probably Turbine)
2. You have the smaller 24mm axle Ride cranks


The solution for situation 1 is simplest. Buy a set of Atlas cranks in your preferred length. Shortest you can go is 165mm. If you buy the longer 175mm you can drill them down to 155. You can also drill Turbine cranks shorter, if you prefer that route. 170 to 150 is possible and 175 to 155 as well. Turbine is sold out everywhere so might not be the easiest option. Turbine does not come shorter than 170.
After you get your new and optionally machined cranks, fit them with the original spindle that came with your bike. It should be a RF149 spindle (149mm end-to-end spindle length). Also fit the original clutch spider assembly with the 30mm locking ring. Install on bike and you are done!

Now situation 2 is more complicated, because you dont have the parts to use the 30mm cranks, and re-drilling the original Ride cranks is not recommended due to the internal structure. So the only option is to first install a 30mm bottom bracket (for example a BB92 Double Row CINCH 30mm with 92mm shell width). Then you need to buy the correct length 30mm spindle. Rocky Mountain advises the RF149 (149mm end-to-end spindle length), and that is what most people seem to use. You can buy these spindle kits at several web shops. You also need to contact RM or you local RM dealer to get a hold of the 30mm locking ring for the spider clutch. For the remainder, the same applies as for solution nr 1; get a set of Atlas (or Turbine) cranks, optionally drill them to desired length, fit cranks with the new correct sized spindle, install original clutch spider with new 30mm locking ring, and you are good to go.

One point to remark is that you can also buy Atlas cranks in so called "83mm" variation. On the Raceface website this shows as "Spindle Size 151". These cranks come with the 151mm RF151DH spindle already attached to it. Now im not sure these will fit the bike, but the difference is only 2mm compared to the recommended RF149 spindle, so perhaps minor enough that you can adjust the free play with free play adjustment ring, or perhaps a spacer. This would save you the hassle to buy a separate spindle kit for another 100 bucks.

This document from Race Face provides you with information on the available spindle sizes.
Note that it says:
• Spindles with suffix “BM” or “DH” (eg.RF136DH) are compatible with SixC and Atlas cranks only
• Spindles without “BM” or “DH” suffix (eg. RF134) are compatible with Next R, Next SL and Turbine cranks only

So according to the document the Atlas crank should not be compatible with the RF149 spindle, but is compatible with the RF151DH spindle. However on the facebook group Norman mentions he has successfully used the RF149 spindle with his drilled Atlas cranks without any problems.

Atlas cranks drilled from 175 to 155 by Norman:

Turbine cranks drilled from 170 to 150 by Andy:

According to Andy, drilling 175 Turbine to 155 is also possible.

So there you have it. I have not verified any of these solutions, so i cannot guarantee the information provided here is correct. But hopefully it helps you get started.

Can I send you a set of 175 to be machined to 155?. or if you have a set you would sell ? thanks

 

[S13]

No sorry, i dont do any machining. I simply bought the Atlas cranks in 165 and upgraded to 30mm bottom bracket.

 

[makeithappen]

No sorry, i dont do any machining. I simply bought the Atlas cranks in 165 and upgraded to 30mm bottom bracket.

Awesome , did you feel like 165 were ok ? or wish you went 155 or shorter ? Thanks for getting back to me I apppreeiate this thread to help me out

 

[S13]

Awesome , did you feel like 165 were ok ? or wish you went 155 or shorter ? Thanks for getting back to me I apppreeiate this thread to help me out

At the time i kind of wanted them to be shorter, but now i feel they are ok. Its a bit of a trade off between natural feeling of motion (i have long legs) and ground clearance.