Firstly, I’m new to this forum and appreciate I might be asking fairly dumb questions, so I wanted to say thanks for your patience in advance.
At the start of February I snapped my pedal crank arm, whilst standing in the saddle, cycling up a hill in London. Long story short, it didn’t end well and I haven’t been able to cycle since.
I use a cheap £500 24 speed sirus hybrid for work and scooting about town (doesn’t get nicked) but have replaced everything on it (inc the crank set) with exclusion of the headset and bars. The general consensus is the cast crank had a hairline crack and then fully stress fractured under load.
I should be able start cycling again soon and this incident has hammered home the importance of having fairly bulletproof parts where your life depends on it.
So I’d really appreciate advice on forged crank arms and whether I can replace the arms or should do the whole crank set. Finding 24 speed crab sets seems harder than I would have expected.
Also, I’d there anything else I should sort to avoid hurling myself under a lorry? I just did the back wheel, so going to get the front built too. Head set and bars?
Do I kind of want to max out strength and durability at a price that is commensurate with the value of the bike, so it retains it primary purpose- functional and not that stealable. That said, I’ll bite the price bullet when and if I have to
Thanks again ☺️
by Milomix
4 Comments
This might interest you: [Shimano recalls 760,000 Hollowtech road cranks due to 4,519 incidents of ‘separation or delamination’](https://www.reddit.com/r/bicycling/comments/16ok6q4/shimano_recalls_760000_hollowtech_road_cranks_due/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button)
See also other articles on the search “recall shimano crank arm”
Generally speaking, what you experienced with your crank is a fairly unlikely incident to happen. Probably a manufacturing defect or a result of a previous misshandling or accident.
A 24 speed crank in that sense doesn’t exist. These are called 3x cranks and while an 3×8 crank exist they are not called 24 speed cranks. Maybe that’s why you’re having a hard time finding them.
In my opinion you should replace the whole crank since I don’t know if you can buy the drive side part of those alone anyway. Make sure it fits your bottom bracket (square tapered I assume?) and has the chain ring sizes that you want and that suit your front derailleur. You could also take this opportunity to upgrade to some sort of 1x drive train for ease of maintenance (no front derailleur to mess things up). A 1×11 Deore can be bought for around 120€ or less where I live so maybe that’s something to think about.
Cranks don’t snap like that. You mentioned a hairline crack. If you spotted it before the incident, it should’ve been a sign to replace the cranks ASAP.
As for replacement. Just get the same crankset. Or similar like FC-M360 (yours seems to be a 48t)
As for the headset and handlebars, just check the wear. Check if the handlebars are bent, have any signs of indentation, especially around stem. If you are worried, just get a good quality set, not the cheapest.
As for the headset, it’s extremely rare for them to fail catastrophically, and usually even worn ones can work for ages. As long as your headset isn’t loose, you are good.
Shimano QC is out of control since the pandemic. 🙄