Crankset – help out a muppet!

Hi, had to make a trail side repair on son’s mtb when pedal made a bid for freedom and I must have managed to knacker the threads on the left side crank arm. It’s a Whyte / Prowheel MPX11 crankset. 10 speed, 32T chainring with 170mm crank arms. Boost and a BSA bottom bracket. I would be delighted with a direct replacement, but can’t find the MPX-11 in stock anywhere. I have a wanted ad in the classifieds, but looking at other options in case no joy on that front. Does anyone know of a sensibly priced replacement? I’ve been looking at the Deore M5100 and also SRAM SX Eagle (though it seems to be 12 speed only). But between hollowtech, boost, dub and powerspline I’m in a right muddle. If I can’t get it worked out I will take it to LBS, but I’m stubborn and also confident in the help of STW! Thanks v much for any help.

https://www.bikeparts.co.uk/products/shimano-deore-fc-m5100-deore-chainset-10-11-speed-52-mm-chainline-32t-170-mm?currency=GBP&variant=40867632349341&utm_source=google&utm_medium=cpc&utm_campaign=Google%20Shopping&stkn=a894e8283159&gad_source=1&gclid=EAIaIQobChMIv9yH1ZSahgMVqphQBh3PDQoUEAQYAiABEgIRqvD_BwE

OK, first up, don’t worry if it’s a 12 speed crankset, they work fine with 10 speed

In your situation I would look for a deore crankset with a suitable sized chainring. These are hollowtech ii cranks and have a 24mm spindle. Pick up the Shimano hollowtech ii threaded bottom bracket and you are set. It just all works together.

Merlin have the MT511 crankset for under 40 quid which is a bargain.

There are two solutions that may work, get helicoil repairs fitted to the threads you stripped or put a longer bolt through with a nut on the end? The second solution is not pretty but all that you’re doing is pinching (gently) the crank arm to clamp the splines. Most bike shops, garages or motorcycle shops will fit helicoils.

Thanks both, much appreciate the help. I checked the bike spec more carefully and turns out BB is already hollowtech 2 so that should simplify things if I go the Deore route. I also have the offer of a use Prowheel MPX12 crankset which is my first choice. I think it is the same, but 12 speed chainring so good to know that this is unlikely to cause issues. I might also ultimately investigate the helicoil option so at least I have a working original set. Will post an update once sorted – thanks again!

How knackered are we talking? I was able to screw a pedal in from the back where the threads were okay and it sorted out the threaded bit on the outside enough that I can put a pedal in normally and it works fine. If not you might be able to get the threads chased with a proper tool or if it’s really borked then the helicoil option is supposedly good as new once fitted.

Sorry- just seen the photo of the pedal at a very funky angle, probably a helicoil would still work.

Ignore my advice, I misread but also was misled by the pictures. I thought it was the crank clamping bolts that had stripped. Go to your local bike shop, if they can’t helicoil it then they will usually have a stock of secondhand, left hand crank arms. Whyte might even help you out – their customer service used to be excellent.

Helicoil will fix that. Done the same. Failure to tighten the pedal causes precession as the steel pedal axle reams out the softer alloy threads and then the pedal falls out. Any decent bike shop will fix it and you won’t notice the new threads.

As everyone(ish) says, it’s commonly done and easily fixed with a helicoil. I used to have to regularly take the pedals off a bike for transportation and opted for Shimano cranks with steel inserts to offset my cack-handedness. Annoyingly I can’t remember what they were though they probably don’t make them any more anyway. Not Saint, maybe the group below, whatever that was?

Reading that Shimano 12s chains have different roller profiles and corresponding tooth profiles and didn’t work with 11s components I bought a 12s Deore chainset and an 11s ring to fit for my 11s bike. I tried the 12s ring with 11s chain out of curriosity and it ran fine, but fitted the 11s ring all the same. By the time you’ve paid postage to send your crank off you won’t save much having it helicoiled compared with a new Deore chainset.

https://www.18bikes.co.uk/copy-of-workshop-job-helicoil-crank-per-side.html

Not Saint, maybe the group below, whatever that was?

Hone?

didnthurt

Full Member

Not Saint, maybe the group below, whatever that was?

Hone?

Thanks, yeah, I think that was it, it was bugging me. Definitely twin and bash at any rate. Bash was less about any core pretensions, more about realism regarding my fitness!