BeeRich

Hi folks. 1992 IronHorse MT700R. This is my baby.

Replaced the chain because of chain stretch. Found the stretch was significant. So, measured the chain according to the link count. So it's effectively shorter.

Found significant chain skip, mostly on mid-range gears. Dang, cassette should be eroded and sprockets all messed up. (see images) I'm not versed on cog/tooth design for better shifting, and what a proper design should look like.

Replaced cassette, slightly different tooth counts, but ya. Problems moving in and out of gears...

Anybody know how to troubleshoot this?

The rear derailleur is lubercated, so I'm thinking the upper pulley might be a bit close for some reason. Not sure if this is correct, but I think it is that. Do I use adjustment screws to keep it away from the new hub? Or can I just increase the distance by taking out another link in the chain?

Options? Ideas?

Cheers

andrewclaus

Did you put a different sized cassette on? It looks like a larger range. If so, your derailleur may not have the chain wrap capacity needed.

Carefully shift into the large/large combination, but don't force it if the chain is too short. The derailleur pulley axles should be at a roughly 45 degree angle to the ground. Then try small/small--the chain should just about be touching the top pulley. If you can't achieve those conditions, you'll need a different cassette or derailleur.

BeeRich

Old cassette was 11-27 teeth.
New cassette is 12-32 teeth.

But the issues are across the range. Looks like it needs some tuning for me to be sure what's going on.

Small-small works, but I don't use that combination.

Large-Large doesn't work, as the cage plate tab hits the sprocket. But I don't use that combination anyway. But I see what you mean by replacing the cassette to make this work.

nick_a

Try tightening the b-limit screw. It will help get the derailleur further away from the large cogs.. not sure, but I think that xt derailleur should be able to do 32.

dedhed

You installed a new cassette and chain. Your RD needs some fine tuning on the cable adjustment.

BeeRich

Ya the tab that keeps the chain on the pulley, knocks the teeth. Never did that before. That outer cog is a big one.

BeeRich

Will be assessing just that in the next couple of days. Cheers

Leisesturm

The size of the small tooth is not the dealbreaker here, the size of the big cog at 32 is an absolute and complete dealbreaker. There is no 'adjusting' out of a size mismatch that large (27T - 32T). A new chain, long enough to wrap the big/big combination of the now much larger big rear cog needs to be made. And, yes, it is entirely possible that a bike sold with an 11-27 cog may need a new RD to shift a 12-32.

BeeRich

The chain is new, and I have the extra links. But I've never used the large-large combination. It's a 3-by-7. Plenty of combinations to get that large-large combination, without bending that combination. I'll give it a tune-up and give it a whirl.

Leisesturm

Spit happens. You never used the large-large intentionally. Are you sure it's NEVER happened? It wouldn't have mattered. Your old chain was sized properly, and there would not have been any damage even if the large-large was selected accidentally. Now, your chain is way too short and may not even be long enough for a reasonable combination, I don't know. It's always wise to follow the best practice for a given operation. The cage on that derailleur is definitely a 'medium'. Will it clear a 32T? It is far more likely that the old cassette was 12-27 and the new one is 11-32 (8sp!!) than what you have said in the o.p. As I suggested in your other thread, you are best off taking this bike to a co-op and you can watch them work.

BeeRich

So now you think I can't count cogs. Like I said, taking a bike anywhere in this town means you don't see your bike. I can get the RD to use the largest cog, but not with the largest chainring. I have the old and new cassettes here. 11-27 to 12-32.

alcjphil

The inner cage of that derailleur is upside down. The tab should be at the bottom, not the top

BeeRich

Oh well that should certainly help. Thank you. I replaced the pulleys last year.

mitchmellow62

BeeRich: I don't understand the reluctance to get the chain length right. You seem to have the mechanical aptitude but lack experience. Park Tool videos (among others) can remedy that in this case. I suppose if you want a quick way, you could add 5 half links (count 5 pins/rollers) to what you have and be in the ballpark. Then you can focus on rear derailleur adjustment knowing that the short chain isn't affecting the derailleur in the larger combinations. Again, plenty of good videos to guide you.

BeeRich

No reluctance at all. Like I previously posted, I have a brand new chain which I sized according to the last setup with the last cassette, and I have the extra links. Simple to add some. I was also told the back of the cage is upside down, so that should help as well. In fact I'll be trying that first. Lots to move on, just need the time.

dedhed

But you changed to a different size cassette.

Even simpler to just do it right the first time.

"We do it right because we do it twice"

BeeRich

If you have that much time to research bicycle parts for days. If you look closely, that's why I'm asking in here. It's a bike forum, in a section called Bicycle Mechanics.

BeeRich

I know what you're saying, but I don't see how that image has any relevance. You're just pinching a chain. Is there no more chain left? I don't use big:big, and it is often spoken about to avoid using such.

mitchmellow62

I'm not sure we're getting through. General consensus is to lengthen the chain and then see about derailleur adjustment. But it's your bike so I wish the best of luck.

Bill Kapaun

You're not even very good at being obtuse.
Ignore list.

BeeRich

OK, this is what I actually took out of the previous post before I submitted: "I will repeat, it's a new chain and I have links. I have no reservation lengthening it."

I've now said it at least twice. What part is confusing?

BeeRich

Why not explain your image?

Eric F 

I don't know if anyone else has mentioned this...the upper pulley is supposed to have a little side-to-side play on Shimano derailleurs.

It sounds like the derailleur just needs proper adjusting for the new cassette. If you're not familiar with the process, there are tons of videos on YouTube on what to do and how to do it. If that doesn't work for you, I would suggest seeking professional help from your LBS.

mitchmellow62

So do it and report the results.

dedhed

And multiple posters have said install chain to correct length, fix derailleur cage, and adjust