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something is skipping under power but gears don't skip.

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something is skipping under power but gears don't skip.

Old 05-08-21, 07:22 AM
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Lamwow14
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can't hold a gear under load

Hi,
when I put power on the pedal the gear is skipping (not jumping to another gear). Is it the free wheel or the rear derailleur? I have a new cassette, chain and chainring.

Thank you,

Patrick
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Old 05-08-21, 07:34 AM
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Motorazr
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Google "freehub slipping" - lots of helpful information and tutorials online.
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Old 05-08-21, 07:38 AM
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This question belongs in the Bicycle Mechanics subforum.

And you will need to provide more info. What do you mean by "skipping"? Is the chain skipping on the cassette? Is the freehub slipping?
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Old 05-08-21, 02:34 PM
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With a new cassette, my guess is you probably need to adjust cable tension or the “b” screw. Lots of YouTube videos on setting up the rear derailleur.
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Old 05-08-21, 04:33 PM
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did you put the shim on for the new gears?
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Old 05-08-21, 07:36 PM
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Is it a freewheel or cassette, you mention both, but they aren't the same thing.
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Old 05-08-21, 07:43 PM
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Can you at least hold your #2s?
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Old 05-08-21, 11:24 PM
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I had the freehub in my Gravel bike go bad, it exhibited the exact problem your describing.
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Old 05-09-21, 09:32 AM
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Have you had your derailleur hanger alignment checked?

That might not be the problem but it's a relatively cheap, easy and non-invasive test. You need to make sure everything is in the default alignment before blindly making changes.
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Old 05-10-21, 07:02 AM
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The mech skips when under load but stays on the same gear. It's a new wheel/freehub/cassette, new chain, new chainring. I ordered a new rear mech to rule that out.
I googled how to remove freehub body and it's a 15mm hex key, is that right? The 10 mm hex key just goes straight through.

Thank you for input.
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Old 05-10-21, 07:03 AM
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It's all lined up and shifts perfectly on the bike stand.
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Old 05-10-21, 07:08 AM
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something is skipping under power but gears don't skip.

Hi,
under load, the rear cassette, hub or something is skipping. I have new wheel and cassette, new chainring and new chain. I ordered a new rear mech to rule that out. Should I remove the freehub body and is it a 15mm hex? The 10mm hex goes right through.

Thank you for any help,
Pat
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Old 05-10-21, 07:12 AM
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A new rear der won't cure skipping due to common issues like cable miss tension, bent hangers, tight links and other miss matched parts. Andy
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Old 05-10-21, 08:04 AM
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Freehub body may need a flush and lube as the pawls inside may be sticking causing the skipping you describe. Sometimes pawls and/or springs break but try lubing first before taking it completely apart. What brand and model is your rear hub? If you have Shimano here's a video on the easiest way to lube it. If yours is not Shimano do a search on YouTube for your hub.

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Old 05-10-21, 08:19 AM
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Old 05-10-21, 09:58 AM
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When my very old bike was skipping under power, it was the chain being worn out. I changed the chain and everything was fine. If you have changed the chain recently then is it skipping on the front or back?

If front, change the rings or entire crankset. If the back, change the freewheel or cassette.

If you remove the chain and wrap it completely around the cog or ring you suspect, then you can sometimes tell better that the gear is worn.
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Old 05-10-21, 02:00 PM
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If you did, in fact, get an entirely new wheel, chain, cassette, chainring(s), and rear derailleur, that is everything the chain touches. You should not have to remove the freehub from the wheel of a new wheel though any of your new parts could be defective - can't rule that out. Are you 100% sure the parts you have are all compatible with each other? Even though the brand or name of a part is the same, there are differences in the number of gears and dimensions that can cause issues when under load.

Assuming all of the aforementioned parts are compatible and correctly manufactured, the only thing I can think of right now is the bottom bracket and/or crank spindle interface. Have you checked your bottom bracket bearings for looseness and your crank for wear? I've seen square taper and splined cranks get rounded out before, but this should be pretty noticeable as you'd see the crankarms were no longer aligned along a 180 degree axis after you feel the bike "slip".

A list of parts and pictures would be helpful.
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Old 05-11-21, 06:25 PM
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Just a thought, but as the chain was replaced, could it be too long?
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Old 05-16-21, 06:39 PM
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Thank you all. I replaced the cassette to rule it out and now all is well. I was fixing my friends bike and "new" means different things for different people. It's hard to evaluate wear on a cassette and it looked in good shape but I guess it wasn't.

Thank you for all the help,

Patrick
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Old 05-19-21, 07:12 AM
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Good to hear. There are tools to measure chain, chainring, and cassette/freewheel wear.

As you just learned, visual inspection of these components is not an accurate way of assessing wear. I find that if chainring, cassette, or freewheel teeth are visibly worn (making the teeth look very curved and pointed like a shark's fin), that usually means that the entire drivetrain is worn and must be replaced wholesale. Anything less than that is a toss-up until you put a gauge on to test the wear.
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