Tech Gremlin - Please help

[robsc]

That a new chain ? It looks very stretched if you look at how it aligns with the teeth on the chainring . Could just be the picture though ??

[s14phoenix]

If I look at your pics - your FD says MEGA 9 clear as day - 9sp derailleur so it is a bit wider to accommodate wider 9sp chains etc. so when the inner plate pushes the chain up the outer plate could be far enough away already so that the chain easily goes over the big ring.

 

The settling on the big ring issue is a chain stretch or ring wear issue on the big ring. Could also be a sticky gritty chain.

 

I am no mech but that's what I see. make sure all is 10sp or all is 9sp (chain, FD, big ring)

 

I have used 9sp FD on 10 sp but it can be a bugger to set nice and keep it working.

[Flashfozzy]

Did you put on a New chain or just another chain?

If you look at the pics the chain is seated on one tooth and 7 links later the tooth lines up with a roller. Chain appears to be badly stretched

[David Greyling]

Hi guys

 

Thanks so much for all the input. To confirm the following:

 

Brand new chain and chainring, both have done 32km on mostly tar with about 100m of dirt just to test it after coming back from the shop. I double checked the chain this morning and it doesn't even get to the 0.5 wear mark, it's literally brand spanking new. To be fair to the shop, the issue existed prior to taking it to them so it is in no way the fault of the guys there.

 

The FD, as S14Phoenix spotted is a 9 speed (I'd forgotten that) but my assumption was that paired to a 10sp shifter and with careful limit setting that it should be fine. However, that could very well be the issue, might try source a sram 2x10 FD and test it, thanks for picking that up.

 

@The real MJ - could also be a problem actually but I don't personally know. the shell is a 73mm and the BB is installed with no spacers on the drive side and a single 2.5mm spacer on the non-drive side. from what I can read on various forums this seems fine. It was installed that way at the shop too so I guess it's correct.

 

Again, thanks a lot to everyone for inputting, this thing is driving me nuts so your help is greatly appreciated.

[dirtypot]

To my eye (and I am actually a bike mechie) it looks like the limit screw is set too far out.  If you trim it in does it not go up to the big ring?  

Your FD is also too high - your picture to show this height is taken from above, but the others are more level.  It really should be just just above the top of the teeth - high enough that it's not engaging, but no more. 

Lastly, are the two chain rings compatible?  Different rings have different shift ramps.  Are the sentients (little pin on the big ring and little nub on the small ring) lined up with the crank arm?

 

My main thought though as it was yesterday is that the chain is being allowed by the FD to go too far up and over the big ring.

[Erroli8a8]

is it my eyes? does it, in the second last pic, look like one of the teeth is outside the chain? if a tooth is bent then this would cause your issues. 

[JXV]

Surely 9spd and 10spd component mix is the only obvious issue here. Small but significant difference in chain width and cog spacing between these systems

[BDF]

+1 for what s14phoenix and dirtypot said.

[David Greyling]

Great, thanks to everyone. I think the initial solution at least is to change out the FD for a sram 2x10.

 

Just a quick question, will the combination of a shimano slx shifter and a sram 2x10 FD (as per standard spec on the specialized) sort the issue? I know in a perfect world you'd probably change the shifters but as the RD is an XT I think sticking with Shimano shifters is advisable.

 

Many thanks in advance.

[Captain Fastbastard Mayhem]

Great, thanks to everyone. I think the initial solution at least is to change out the FD for a sram 2x10.

 

Just a quick question, will the combination of a shimano slx shifter and a sram 2x10 FD (as per standard spec on the specialized) sort the issue? I know in a perfect world you'd probably change the shifters but as the RD is an XT I think sticking with Shimano shifters is advisable.

 

Many thanks in advance.

doesn't matter what brand the FD / Shifter is. As long as it's the 10sp 2x and the derailleur is the type that the frame originally shipped with (ie high mount low mount etc)

[Spoke101]

Just a quick one. What size small ring is on the crank? guessing a 22T?

If this is the case, check the inside of the big chainring as some are designed for use with a 24T only and should state so and thus have the pick-up points higher up, closer to the teeth on the large chainring (if that makes sense).

[David Greyling]

Just a quick one. What size small ring is on the crank? guessing a 22T?

If this is the case, check the inside of the big chainring as some are designed for use with a 24T only and should state so and thus have the pick-up points higher up, closer to the teeth on the large chainring (if that makes sense).

 

Now that I wasn't aware of, I'll check it out when I get home this evening. Shot for the heads up.