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Drive Train help!

adskisadskis Posts: 85
edited December 2017 in Workshop
I need some help. ( :wink: )

Recently I was getting some chain slip from the bike.

I replaced the chain, cassette, rear mech, middle and big rings and the gear cable and all the outers (it's been a while since I changed anything and they were all knackered)

I am still getting chain slip on the middle ring and yesterday I nearly ended my chances for more children!!

This is doing my head in... Everything is new. I just dont get it.

I have obviously done something wrong, but I cannot figure it out!

Hive mind required. Please!

Bike: PX London Road (Flat Bar)
Chainset: 9 speed XT MTB HollowTech 2
New Chain: 9 Speed XT HG93
New Cassette: 9 Speed XT M770
New Mech: Shimano Deore M592 Shadow 9 Speed Rear Mech
New Chain Rings: Shimano XT FCM760-M800 9 Speed Chainrings


  • cougiecougie Posts: 22,512
    And it's definitely the chain slipping ? Not the tyre on slippy road ?
  • adskisadskis Posts: 85
    Yep, definatley the chain.
    Only in the middle ring. Big ring is fine.

    Could the ring be faulty in some way? Is that possible?
  • Is it slipping, or skipping? ( jumping over the teeth, or jumping up and down between sprockets)
  • adskisadskis Posts: 85
    Its jumping over the teeth like they dont fit somehow.

    like when you put a new chain on a really worn chainring

    And I checked that I put the new middle ring on and didnt put the old one back on!
  • It’s possibly just something as simple as the new spring in the rear mech isn’t bedded in yet, so the mech isn’t extending and contracting smoothly yet, that should improve with a bit of shifting. Or maybe the cables haven’t bedded into position yet, sometimes the outers can be slightly unseated, and need a few shifts up and down, then a tension re adjust. Make sure nothing is fouling where the cable inner meets the cable outer ferrules, and that the ferrules are properly seated. I always squirt a bit of MO94 into the outers, before feeding the inners through as well.
  • look for stiff links, or if you’ve used a quick link, that it’s clicked together fully. Is the chain directional? If you put a directional chain on censored about face, I’ve had a slipping issue before as well.
  • adskisadskis Posts: 85
    So take everything off and re-fit?

    I didnt lube the cables. Could try that I guess. I have a spare gear cable. Could start again.

    I could check the ferrules are seated properly.

    No idea if the chain is directional. How would I chick that?

    The chain came with a shimano jointing pin. I will check for stiff links - not done that.

  • fenixfenix Posts: 5,437
    I can't see that it's anything to do with the cables. As you say its usually a wear thing.

    Your chain isn't directional so it can't be that.

    When does it slip ? As you change gear (ok that could be the cables) or when you're already on the middle ring ?
  • adskisadskis Posts: 85
    It only slips under high pressure. Like accelerating away from lights, etc.

    If I change down into the middle ring and dont push too hard, it doesnt slip. as soon as I press harder, I nearly end up going over the bars!

    Good to know about the chain direction thing.
  • imposter2.0imposter2.0 Posts: 11,258
    I would ignore the 'directional' thing, it's nonsense. While fitting a directional chain the wrong way might affect shift performance and wear (still unlikely, IMO) it would not make the chain slip in the way you describe.
  • fenixfenix Posts: 5,437
    There's no way you've put the chainring on back to front is there ?
  • adskisadskis Posts: 85
    Ummmm... dont know.

    Dont think so. The lifting ramps should be on the inside, no? I will have to check that one.

    There are no issues shifting into the middle ring from the granny ring, or down from the big ring. But I will check that one tonight. Can you fit it inside out?
  • cyclecliniccycleclinic Posts: 6,865
    a stiff chain link is the likely culprit. -wheel building and other stuff.
  • jermasjermas Posts: 484
    It sounds very much like the freehub is slipping (the pawls aren't engaging properly). When this happens it feels like the chain is slipping even if it's not. It mostly happens after stopping then pulling away or free-wheeling. The freehub might need a clean and relube if it hasn't been done for a while (or ever).
  • adskisadskis Posts: 85
    The wheels are fairly new. (Less than 1000 miles) And it doesnt happen in the big ring. I can get out of the saddle and stomp in big, no worries.

    New bike is a bit of a mish-mash
    New frame from Planet-X (London Road)
    New BB, Headset, seatpost, etc.
    I built up new bike from other old bikes with some new bits to make it all compatible.
    I stuck the old drivetrain on the new wheels.

    Biggest donor bike was an old MTB (hence all the 9 speed MTB stuff)

    Needed new 700c disk wheels to fit the frame so they were new. Stan's Grail X on SuperStar Switch Ultra-LITE ROAD Hubs.
    I guess they might need a service with all the road grime.

    I am doing about 100 - 140 miles a week in all weathers
  • adskisadskis Posts: 85
    So: overnight update.
    I took most of the drive train apart last night.
    Checked the chain for stiff links, (no joy there)
    Checked I had put the chain rings on the right way around. (yep)
    Checked the hubs on the wheels, the grease was still shop bright green (so I think thats okay)
    Checked the cable was running free and all the ferrules were seated (again, yep)
    Re-adjusted the indexing
    Lubed everything within an inch of its life and reassembled it all.

    Well, no aparant chain slip today. Hooray!!!
    Caveat: I really wasn't very brave with the amount of pressure I was willing to push through the middle ring as I like my manhood intact, but I gave it a fair bit.

    So I guess I had done something wrong and all my fettling lasst night somehow might have resolved it.
    Still absoutely none the wiser about the cause. And it may return, but for now....

    Thanks for all your help everyone.
  • jermasjermas Posts: 484
    If the freehub was at fault, it can be the grease itself that causes the problem by sticking the pawls open (it depends on how strong the pawl springs are, how sticky the grease is and temperature). Some oil to thin the grease helps.
    Anyway fingers crossed all's well.
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