tnike

I have a 2011 specialized secteur that came with sora groupset on it.
I always keep my bike properly cleaned and lubed.
recently my chain started skipping round every so often on certain gears when I push hard through the pedals such as hill starting, but this would also happen randomly mid pedal strokes, say on the flat. I messed with cable tension and new cables etc but no joy and the cogs started to show signs of being damaged.

I checked with the chain wear indicator and it wasn't yet even worn to 0.75 but I made the decision to replace the 9 speed hyperglide hg50 cassette, 9 speed HG93 shimano chain and chain rings. I replaced like for like, however the problem is still there! with brand new compatible drive chain components too! The rear Tiagra derailleur looks pretty level with the chain and normal and the top jockey wheel is clear of the cassestte, plus i've tweaked the cable tension so it's indexing fine when I try it in the stand - can't replicate the problem in the stand either which is odd, but maybe it is something to do with the derailleur malfunctioning when force is put through?? I might add also that the skipping / tripping of the chain is happening on most cogs and appears not to skip onto other cogs when the problem occurs.
Any ideas appreciated before my new drivechain components get trashed!!

Cheers,
Tim

Andrew R Stewart 

There are other reasons for a skipping then chain/tooth meshing. If the der is well adjusted, not twisted or otherwise damaged, then it is unlikely to be the problem. The first possibility I think of is the freehub's ratchet is wearing. Much like a worn chain skip, a ratchet skip will only happen under power and this is hard to duplicate on a repair stand. Another possibility is that the current skip isn't for the same reason as the old one. Like a tight link or link side plate/pin issue. Or the der is not adjusted to the new set up. And to flog the dog one last time, is the hanger bent? Andy.

FBinNY 

Depending on the frequency, my first guess from what it does and doesn't do, is a stiff or damaged link. Put the bike into a middle gear, and push the lower pulley forward so the lower loop sags a bit. Backpedal slowly and watch and feel for any link that doesn't run through the S-turns smoothly, or doesn't straighten as it emerges from the lower pulley. If unsure, or as backup, try the same test but running it through your gingers in a way that it has to bend back and forth as it runs through.

Other than that, there's always the classic misaligned hanger.

Shift to a gear where the cage is fairly vertical and stand a straight edge against the rear wheel (on the right). Standing behind the bike, see if the cage is parallel to the straightedge.

Lastly, if the bike is well ridden, especially if it's a mtn bike, there's always the possibility that the skip isn't in back, but on a chainring. These feel the same, and have the same effect, so it's common to blame an innocent component. Good evidence that it's the ring and not the cassette is that it's on various spockets in back (rare on cassette skip). If it's always on the same ring, that's almost conclusive. Look at the ring for signs or serious wear, which will appear as teeth that are narrowed, or shaped more like shark fins or hooked pointing back. That combined with the other signs says guilty.

Miele Man

But the OP says the chain, chainrings and cassette were replaced with new items. dropout allignmentot frame allignment could be the cause? How about if there's a really worn wheel on the rear mech?

Cheers from Miele Man

FBinNY 

Chain could have been closed poorly leaving stiff link. Historically this is a common cause of issues with newly installed chains, but isn't likely if a connector was used. But it's easy enough to check, and I check it first, following rule No.17 - do simple and free diagnostic tests before spending any time or money.

I don't think the dropout could b the issue, though the hanger could, and yes a pulley issue is also possible, especially with floating pulleys that maybe don't float well anymore.

We don't have the bike, the OP does, so he has to observe and see if he can rule possibilities out or work them down to the short list.

tnike

Thanks for the input. Before I list the checks I have now made, a little more info on the bike so you get the idea that this is really not a worn bike. I got the bike from a friend who bought it brand new and had never used it. I've only been using it for just under a year -albeit frequently for commuting approx 10-15 miles a day and with a extra weight (often about 4-5kg, but certainly never more than about 10kg in a carradice saddle bag) but the bike has always been properly cleaned, maintained and lubricated. It has never had a crash or knock and I'm pretty sure it's never even fallen over.
Checks I have now made since reading these posts are:
1. Hanger is perfect.
2. Dropouts are fine and wheel sits in dead straight every time.
3. pulley wheels on rear mech are in good condition
4. no stiff links detected in chain. It wasn't a speed link but I did make sure to loosen the link properly with a few firm lateral wiggles.

So, are there any other checks I can make or would you say it's looking looking like the freehub body? Has anyone heard of a freehub wearing out / malfunctioning so soon? It's a shimano FH-2200 and I've got the same one (or very similar) on an older bike that has done many more years distance / service without any problems - so it would surprise me if it was the freehub, but maybe I should try mounting the cassette to a different wheel to see if the problem resolves - Would that make sense?

Look forward to responses,
Thanks again
Tim

**In addition:: since writing the above, I have taken the bike to a friend who is not a mechanic by trade but has been cycling and tinkering with road bikes many more years than myself. He agreed with my appraisal of all the elements mentioned above and did not think the rear mech or freehub could be causing it (apparently it's 'all or nothing' with a freehub - they don't 'partially' malfunction under harder pedal pressures like mine, rather they suddenly and conclusively 'die' and there would be no questioning it. He thought it could be the chain as it looked like it was almost too wide and too close to the sprockets either side but then he put a more expensive 9 speed chain on and it looked exactly the same and the problem did not go. He also took the cassette off and put it all back on again to make sure it was all correct.
He felt confident that in theory everything 'should' be working ok and that the next step would be for me to try a more expensive cassette as this is what it must logically be.
So, the plot thickens, but at least the problem is not the chain, right?? Does anyone agree that I should buy a more expensive cassette? He suggested at least a 105, but at first online glance I think they only do 10 speed. Can someone tell me if a 10 speed will fit onto the same hub with no spacing issues? of course then I'd have to buy a new 10 speed chain aswell.
Help me Obi Wan Bike Forum, you're my only hope!!
:-(

tnike

Hi,
So the latest is I've acquired a derailleur hanger alignment tool and sorted a slight discrepancy out. The problem resolved slightly but still did not go away.
Next I changed the rear mech for one off another road bike that I've never had problems with - problem still did not resolve.
Thinking it might be a dodgy freewheel, I put a different back wheel on - problem still there!
The situation is not as bad as it has been but the chain still slips and skips when I push hard in the lowest gears on the bike - I dread steep hill starts out of the lights cos I know the chain will probably slip and I'll be on the floor if the chain snaps.

Although the shifters are barely a year old (2012 or 2011 edition Sora 9 speed) I noticed it was nearly impossible to get the indexing right on all gears for instance the first click from smallest cog wouldn't jump it to second cog, I had to click it twice no matter how much tension I put on the cable , but aside from that, when I got it shifting up every other cog with a single click, I found it would not skip down in the same mannner - so turn the barrel adjuster gradually in to gradually take off tension until it skips down each cog right? well by the time it was shifting down well, it would not shift up properly and vice versa - impossible to get the sweet spot where cable tension shifts up and down every cog with a single click of the shifter. So now I'm thinking it MUST be the shifters or the shifting cable circuit right!!??? So I've bought new 9 speed shifters.

If it is the shifters - how would this create the problem in the lowest gears!??

Thanks for reading. Input appreciated!

speedy25

Maybe you have the same problem I encountered this summer on my Allez.

The inner core pulled out of the outer cable (NOT the inner cable) and made my shfting go wonky and then it was totally stuck. I didnt find it until the brifter was getting stuck and I pulled it all apart.

-SP

tnike

AH! thanks, I had no idea that could even happen but I'm willing to believe it might be something like that now as I've ruled out so many other causes. I'll replace the cables, housing and ferrules and let you know.
Thanks again
Tim