Mysterious Skipping/Slipping

[onomic]

I've been troubleshooting some mysterious skipping on my Parlee Z5 and it's driving me nuts. I am getting very slight skipping/slipping in the drivetrain every 2 1/2 to 3 pedal strokes. It's not shifting gears, the adjustment is spot on. It just feels like the chain is slipping forward. It happens in any gear and on both the little and big chainrings. It is more pronounced when I'm really putting power into the pedals, every 2 1/2 to 3 pedal strokes I feel it slip slightly. At first I thought it was in the freehub body but I overhauled that (it's mavic) and it was still happening. I put the wheel on my merlin and no issues whatsoever. So onto the chain, I checked it with my park tool and it has plenty of life left. I even flipped it around and checked every link for a stiff or bent link, it's perfect. The drivetrain (cogs and chainrings) have at most 2,500-3,000 miles. The bottom bracket is tight, no play, it is BB30 of which I'm not a fan but those bearings only have maybe 1,500 miles. I am running sram force:( and my last thought is on the rear derailleur, it does have a bit of play in it where it mounts to the frame but it doesn't feel excessive. Any thoughts, anyone run into this same issue? I'll take any and all suggestions as I'm out of ideas.

[Louis]

If you're sure that the freehub is good (which you are) I'd try a new chain. For some of the new narrow chains that's quite a few miles, even though your check says that it's OK.

[eddief]

seems like if the chain is engaged on the chainrings and around the cassette it be would hard for slippage to happen at those interfaces. I think you need to try to better describe the slipping thing. Like a couple of teeth worth or something more? Is the cassette torqued correctly? What crank are you using? How about chainring bolts or crank arm fixing bolts?

[Mikej]

Does it skip in every gear and is your derailluer hange aligned correctly? I recently went through this with my sons mtb.

[Peter P.]

Regardless of what you found when you checked the chain, I think it IS the chain.

While you may not see it, there is a corrupted link in the chain.

It would be easy and cheap to prove.

Buy a replacement chain and install it, saving the existing chain. Ride the bike and if the problem goes away, toss the old chain. If the problem remains, reinstall the old chain, save the new chain for future use, and investigate further. No money lost.

You could have a damaged roller on the chain and just not notice it.

Because the problem happens every 2 1/2-3 crank revolutions, it sounds like it occurs when the chain passes around the rear cog or chainring.

[bargainguy]

Check the jockey wheels on the RD, make sure they're not worn.

[onomic]

I'm running a sram 1070 cassette and force crank. I've checked the chainring bolts and bottom bracket. I do have a new chain so I'll have to give that a shot. The thing about worn or bent teeth is that doesn't make sense is that it does it in any gear combo. It's the weirdest slipping I've ever experienced, the best way to explain it is a very slight momentary slipping maybe lasting an 1/8th of a pedal stroke before it stops. I hate climbing with it because my legs can't figure out what is going on. Crank, crank, crank, slip, crank, crank, crank, slip. I've had a friend watch me on the rollers and he can't see anything slip or see a change in my pedal stroke but I feel it and it's there. I'll try the chain and double check the BB, maybe I'll get lucky and that'll work.

[onomic]

Good thought about the chain and the rollers, that makes sense, didn't think about that. I'll check the pulleys too. If it's still slipping I'll take it to my shop to check the derailleur alignment. Thanks for all the replies, I hope it's just the chain. I'll be thinking about this all weekend until I get home but at least now I have a little hope for a solution. Thanks and I'll post when I figure it out.

[eddief]

"At first I thought it was in the freehub body but I overhauled that (it's mavic) and it was still happening."

What did you do to overhaul it. I am thinking this is the likely slipping mechanism. Maybe you need to double check your work? I have been pedaling and wrenching many years and never rebuilt a freehub body.

[pbarry]

^^ Really, never? How about a freewheel? That's really fun. ;)

[eddief]

^^ Really, never? How about a freewheel? That's really fun. ;)

I ride a bunch of bikes and trade em out before anything breaks :).

[pbarry]

I ride a bunch of bikes and trade em out before anything breaks :).

:hello:

[Russity]

I ride a bunch of bikes and trade em out before anything breaks :).

Remind me NEVER to buy a bike from you....

[eddief]

Remind me NEVER to buy a bike from you....

on really fine bikes in barely used condition.

[lhuerta]

Based on how new ur chain, chainrings and cogs are the only logical explanation is ur freehub body, most likely pawls slipping. Mavic freehubs call for light mineral oil only and any heavy grease will gunk things up and yield sticky pawls which could cause the slipping u r describing .

[oldpotatoe]

I've been troubleshooting some mysterious skipping on my Parlee Z5 and it's driving me nuts. I am getting very slight skipping/slipping in the drivetrain every 2 1/2 to 3 pedal strokes. It's not shifting gears, the adjustment is spot on. It just feels like the chain is slipping forward. It happens in any gear and on both the little and big chainrings. It is more pronounced when I'm really putting power into the pedals, every 2 1/2 to 3 pedal strokes I feel it slip slightly. At first I thought it was in the freehub body but I overhauled that (it's mavic) and it was still happening. I put the wheel on my merlin and no issues whatsoever. So onto the chain, I checked it with my park tool and it has plenty of life left. I even flipped it around and checked every link for a stiff or bent link, it's perfect. The drivetrain (cogs and chainrings) have at most 2,500-3,000 miles. The bottom bracket is tight, no play, it is BB30 of which I'm not a fan but those bearings only have maybe 1,500 miles. I am running sram force:( and my last thought is on the rear derailleur, it does have a bit of play in it where it mounts to the frame but it doesn't feel excessive. Any thoughts, anyone run into this same issue? I'll take any and all suggestions as I'm out of ideas.

I still think it may be FH body. Both because these items wear a lot plus 2 pawls vs 3 like on most hubs. If nort worn out, I lube with Mobil One..cheap, doesn't get thick when cold..

Grab FH body..does it rock back and forth on the 'stub' of the hub? It may be work, rocking, causing one of the pawls to 'miss'.

Every 2 1/2 to 3 pedals...sounds like it could be chain also...

[oldpotatoe]

"At first I thought it was in the freehub body but I overhauled that (it's mavic) and it was still happening."

What did you do to overhaul it. I am thinking this is the likely slipping mechanism. Maybe you need to double check your work? I have been pedaling and wrenching many years and never rebuilt a freehub body.

Really?..some are pretty easy(Campagnolo, mavic), some are essentially sealed little freewheels, w/o the cogs(shimano), bolted onto the hub body..those are great fun..as long as ya got a ton of spare 1/8 bearing balls..

[Vientomas]

Sounds like freehub body pawl slippage. Is there any noise accompanying the slippage?

[onomic]

Thanks for all the advice and suggestions. I installed a new chain and that fixed it. I can't believe I didn't just try that earlier. A simple 5 minute fix. Good tip about the mobile oil for the freehub body, I might try that next time it needs lubed, still plenty of cold temps left till spring.