Crank arm slip?

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Crank arm slip?
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Posted: Jan 17, 2012 at 11:57 Quote
When riding my crank arms can sometimes slip forwards, mainly when applying alot of pressure, up hills etc

Its getting annoying as its when i need it not to it does with a bit of a clonk, but if riding faster has just slipped before without the noise, i think.

Im not with the bike atm but looking at doing a few jobs at the weekend, so looking for some ideas on what it could be and give them a try, bottom bracket? Chainring bolts?

Thanks

Posted: Jan 17, 2012 at 12:54 Quote
New Cassette & chain at the very least, and possibly chainrings. Skipping forward under load is a classic symptom of a worn drivetrain.

Posted: Jan 17, 2012 at 12:57 Quote
does this happen in all gears? or just when your chain is in your smallest cogs at the rear (i.e. 11T/12T) if so, as the previous poster mentioned then its your drivetrain that is worn

if its happening in most gears, its typically your freehub mechanism in your rear wheel that is slipping, and allowing your drivetrain to slip under power, which you will feel through your crankarms

unless your crank arms are so loosely attached to the bottom bracket axle that they are actually rotating on the axle splines, but this would be very noticeable as your crank arms would wobble and work loose

the solution to your freehub problem is to source a new freehub body and rebuild your rear hub, this is often available for Shimano or Formula hubs

if you have an unbranded hub in your rear wheel, it can be very tricky to find a replacement body, and its time to buy a new wheel, I would suggest something serviceable like shimano or Hope for a long term future

Posted: Jan 18, 2012 at 4:29 Quote
I think it happens in most gears to be honest, but mainly when ive changed to a lower gear for hill etc then put pressure on the pedals and it slips, the worst occasion the crank arm did fall off, and i lost the bolt, which was replaced by a bike shop.

As for the rear wheel its the standard one from factory on the kona stinky 2005, its def a 'sun' rim might be mtx or something like that, is this serviceable?

Would it be easier to get a bike shop to have a look and advise me as they can see it in the flesh?

Thanks for the response.

Posted: Jan 18, 2012 at 5:18 Quote
one more thing added to above make sure your derailleur is in a perfect straight line with you gears .....also make sure it has enough tension to keep the chain in place... and if its all good REPLACE EVERYTHING....gear wise..

Posted: Jan 18, 2012 at 5:41 Quote
put your bike ie front wheel against a wall so it can not move get a mate to stand on the peddles and push really hard while you check for any movement in the cassette crank arms chain this is a good way to see whats going on . Ps if you cassette moves while your mate is pushing on the cranks then its your free hub . Hope this helps you find the problem its worked for me over the years and saves you money as you can find the problem and replace it without buying new chain and bits only to find it still slips rahhhhhhhhhhh

Posted: Jan 18, 2012 at 6:57 Quote
superbikes wrote:
put your bike ie front wheel against a wall so it can not move get a mate to stand on the peddles and push really hard while you check for any movement in the cassette crank arms chain this is a good way to see whats going on . Ps if you cassette moves while your mate is pushing on the cranks then its your free hub . Hope this helps you find the problem its worked for me over the years and saves you money as you can find the problem and replace it without buying new chain and bits only to find it still slips rahhhhhhhhhhh

Good idea mate never thought of doing something like that. Thanks

Posted: Jan 18, 2012 at 7:05 Quote
Makaveli1602003 wrote:
superbikes wrote:
put your bike ie front wheel against a wall so it can not move get a mate to stand on the peddles and push really hard while you check for any movement in the cassette crank arms chain this is a good way to see whats going on . Ps if you cassette moves while your mate is pushing on the cranks then its your free hub . Hope this helps you find the problem its worked for me over the years and saves you money as you can find the problem and replace it without buying new chain and bits only to find it still slips rahhhhhhhhhhh

Good idea mate never thought of doing something like that. Thanks
No problem Let me know if it finds the problem mate. PS Alls remember to test both sides when pushing on the cranks.

Posted: Jan 18, 2012 at 7:09 Quote
Only problem is its quite an intermittent problem sometimes it can do it 3-4 times on a 10mile ride other times it doesnt happen.

But will give it a go and report back.

Posted: Aug 13, 2022 at 18:27 Quote
My Race Face cranks are skipping. I think the Cinch chainring interface wasn't tight enough. I tightened it down pretty tight and its much better but still present. Sounds to me the Cinch has to be REALLY tight.

Posted: Aug 14, 2022 at 7:30 Quote
Thirty3 wrote:
My Race Face cranks are skipping. I think the Cinch chainring interface wasn't tight enough. I tightened it down pretty tight and its much better but still present. Sounds to me the Cinch has to be REALLY tight.

Do you mean the chainring is skipping on its interface with the crankset? I’d mark a line on it then see if the line moves relative to the crank.

Posted: Aug 22, 2022 at 3:44 Quote
Is there any play in the crankset at all?

Posted: Aug 22, 2022 at 7:17 Quote
kiranseligman wrote:
Thirty3 wrote:
My Race Face cranks are skipping. I think the Cinch chainring interface wasn't tight enough. I tightened it down pretty tight and its much better but still present. Sounds to me the Cinch has to be REALLY tight.

Do you mean the chainring is skipping on its interface with the crankset? I’d mark a line on it then see if the line moves relative to the crank.

If your Race Face crank arm actually slipped on the spindle then you'd be able to tell immediately. Just hop off the bike and look at the crankarms - they should be perfectly aligned with one another.
If one of them is cock-eyed then the crank arm slipped. This is a very unlikely scenario - a lot of metal would have failed in the process unless it was just really loose to begin with.

Good luck

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