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Discussion Starter · #1 ·
Has anyone changed out the crankarms on their 2020 or newer Switchblade/Trail 429?

I’ve been running my 2020 Switchblade as a mullet and have really liked the results. A downside is that I’ve been getting more pedal strikes, especially after moving to the east coast.
I want to give 165mm cranks a try to see if that helps. I’m also 5’3 so it seems like a good bike-fit move anyway.
I haven’t quite been able to figure out what crankarms need to buy in order to match the superboost chain line.
My Switchblade was spec’ed with RaceFace Affect R cranks, seems like easiest thing to do would be a direct swap for 165mm AffectR cranks. However Pivot says the cranks they spec have a custom spindle. It’s not clear if that refers to spindle length or diameter or both.
Any help would be appreciated!
 

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The simplest option is to replace with a Shimano Superboost compatible crankset. The Shimano XT FC-M8130 1x crankset is in stock at Competitive Cyclist right now for $153.99. It should swap in with your current BB just fine. All you need is a Shimano direct-mount boost chainring to go along with it. Good time to try out the Absoluteblack oval. I'm running this exact combo on my Switchblade in 170mm.
 

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My thought would be that if you are running a RaceFace crank it's got to be a 30mm spindle. RaceFace does make a longer (it's 143.5 mm long) spindle for superboost bikes. I swapped the spindle out on a Next crankset to use on my superboost bike...the spindle actually came with the extraction nut that you need in case you don't have one.

Alternatively, any superboost crank with a 30mm spindle should work...I would have to think. I can't imagine RF is making a custom spindle diameter and BB for Pivot, it really wouldn't make sense.
 

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My thought would be that if you are running a RaceFace crank it's got to be a 30mm spindle. RaceFace does make a longer (it's 143.5 mm long) spindle for superboost bikes. I swapped the spindle out on a Next crankset to use on my superboost bike...the spindle actually came with the extraction nut that you need in case you don't have one.

Alternatively, any superboost crank with a 30mm spindle should work...I would have to think. I can't imagine RF is making a custom spindle diameter and BB for Pivot, it really wouldn't make sense.
Aeffect cranks are 24mm diameter. It is probably a custom spindle length that they are specifying.
 

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Rotor brand Kaptic cranks have everything you need. They sell the arms in 165s, and then you purchase the spindle you need. They sell standard, boost & Superboost spindle lengths.

My wife has a set and they are very well made, well priced for a high end set of cranks, very lightweight and rigid. Rotor also invented the entire oval chainring thing and they sell those rings that are proprietary so you'll one of those as well.

I bought hers from R2.

GL.
 

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The simplest option is to replace with a Shimano Superboost compatible crankset. The Shimano XT FC-M8130 1x crankset is in stock at Competitive Cyclist right now for $153.99. It should swap in with your current BB just fine. All you need is a Shimano direct-mount boost chainring to go along with it. Good time to try out the Absoluteblack oval. I'm running this exact combo on my Switchblade in 170mm.
Competitive Cyclist doesn't have the 165mm crank arm length of the XT M8130 crankset though that the OP wants to try. Nobody online has the 165mm in stock currently; I'd like to try those too. I have seen the SLX M7130 available in the 165mm length though.
 

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The stock Aeffect R cranks have a pretty wide Q factor. That pushes the pedal farther out and contributes to pedal strikes when the bike leans over any amount in rocky terrain.

I switched to standard XX1 Dub crank and dub BB with a oneup switch oval chainring with zero offset. This puts the chain at the same chain line as stock. This set up has smaller Q and pedal strikes are less. The oneup chainring works great with the shimano chain.
 

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I got a response back from Pivot about their stock RaceFace Affect R cranks.

Me: "Is the Aeffect R spindle that comes stock on Pivot bikes the exact same 137mm length as the aftermarket Aeffect R cranks, or did Race Face supply a different spindle length for Pivot SuperBoost bikes?"

Pivot: "We spec the Trail 429 with Superboost cranks which would have a 143 mm spindle. You can run the 136 mm spindle you would just need a 0 mm offset chainring. The Superboost cranks (143 mm spindle) will need a 3 mm offset chainring. The ideal chainline is 55 mm - 57 mm."

I don't see anything online about being able to flip over Race Face's new 12-speed/Hyperglide+ chain rings to get a 0 offset/Superboost chainline (like their previous versions), and I looked at mine and it looks like it can't work that way (the crank arm would interfere with it being able to seat flush properly). The alternative is to use a OneUp Switch Cinch 0 offset/Superboost carrier and chainring with the aftermarket Race Face Aeffect R 137mm crankset. These cranks have a Q-factor of 177mm, which is less than the Shimano M7130 and M8130 crank Q-factor of 181mm.
 

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Discussion Starter · #13 ·
Interesting point about the role Q-factor plays in pedal strikes. I guess the wider Q on the superboost cranksets is a function of the longer spindle and/or to help with heel clearance?
So ideally, shorter crank arms and narrower Q would be the way to go to reduce pedal strikes but probably tough to have you cake and eat it too.
I think i’d rather have the heel clearance and just find some slightly narrower pedals.

FYI - Wolf Tooth makes 0mm offset “superboost” chain rings that are meant to work with boost cranksets on bikes with superboost hub spacing.
 

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Discussion Starter · #14 ·
Just to close this out, I straight swapped the Affect R cranks for Shimano m8130s.
The Affect R spindle is 24mm diameter, so no BB change required.
As for crank length, its a small change but totally noticeable. It definitely feels more comfortable pedaling with my shorter legs. Maybe also better bike control, manuals feel easier and turns a bit snappier. On the flip side, the shorter cranks also feel a touch less stable on descents but well within the range of things you get used to and forget about.
My only ride on them was at a bike park so probably not the best test. I smashed my derailleur cage to pieces on my fourth lap so it’ll be a bit until I get more time on the shorter cranks. But definitely worth a try if you are a smaller human.
 

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Just to close this out, I straight swapped the Affect R cranks for Shimano m8130s.
The Affect R spindle is 24mm diameter, so no BB change required.
As for crank length, its a small change but totally noticeable. It definitely feels more comfortable pedaling with my shorter legs. Maybe also better bike control, manuals feel easier and turns a bit snappier. On the flip side, the shorter cranks also feel a touch less stable on descents but well within the range of things you get used to and forget about.
My only ride on them was at a bike park so probably not the best test. I smashed my derailleur cage to pieces on my fourth lap so it'll be a bit until I get more time on the shorter cranks. But definitely worth a try if you are a smaller human.
You went from 175 to 165?

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Discussion Starter · #16 ·
I went from 170 to 165, because that’s what was “easily” available for my current BB.
Still too early to say if Id want to go shorter. I think the answer is no, at least for a bike intended for mayhem. I can already say that I don’t think I’ll be going back to 170. I was out on my gravel bike today (170mm cranks) and the top of my pedal stroke felt a little too high compared to the 165 cranks I put on my switchblade. I’m seriously considering going with shorter cranks on my gravel bike too.
Apparently, Canfield and Rotor do cranks down to 160 and shorter. I’d give 160 a shot if the opportunity presented itself but it would mean a new BB. Canfield doesn’t make their cranks for superboost spacing as far as I could tell.
 

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SuperBoost+ crank/BB lengths can be really confusing. But here is how it works:

If you are using the stock Pivot/RF Aeffect crankset, it has a 143mm "Superboost+" spindle. The standard spindle length on a non-Superboost crank is 136mm.

The thing to remember here is that Superboost+ was originally designed to work with existing cranksets bitd. So if you use a Superboost+ spindle, you need to use a Boost chainring with a 3mm offset, to get the chainline to be Superboost+ compatible. If you swap your cranks for a regular Boost 136mm spindle crankset, you need to use a 0mm offset chainring, which can be achieved by using something like OneUp's Switch Superboost 0mm carrier and their Switch chainring. The OneUp Switch carrier is what has the offset built into it, not the chainring. Currently, I am not aware of any RF-manufactured chainrings that are specifically Superboost+ (0mm offset), and that explains why Pivot spec'd a Superboost+ Aeffect crankset/spindle, so that they could use an off-the-shelf RF Boost chainring to get the proper chainline.

Personally, I swapped to a RF Next SL crankset with Boost spindle in conjunction with the OneUp Superboost (0mm) carrier and Switch chaining as there were no issues with frame clearance with the arms and it also reduced the Q-factor which I felt was easier on my knees.
 
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