Advice please on gears & derailleurs

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Just changed my Shimano 10s cassette from a 11 36 to a Sunrace 10s 11 46. Also changed Shimano Deore 10s M610 RD to a Shimano 11s M8000 11s RD to cope with the 40t & 46t sprockets. Gear changes are smooth as a babies bum with one exception. Changing from either 8th or 6th gear to 7th gear results in a rough changeover and pedalling in 7th gear is noisy and not smooth, almost as if the chain has not engaged properly. Before making these changes I had read plenty of information where this had been successfully done with no issues. I also contacted at least a dozen bike shops to get their opinions. No negative feedback at all. I'm wondering if the LBS, which is basically a hobby for a competition rider, has not made all the necessary adjustments for smooth changing in all gears. Also his knowledge base is more road bikes than MTB's. He did mention when he competed the changeover that 1 gear would give me problems. I was surprised by this as none of the people who have made the same change said they had encountered any issues at all. Does anyone have any suggestions on how I can have this one glitch rectified. BTW I'm riding a 3x MTB.
 

Globalti

Legendary Member
Did you ask them to change the gear cable inner and outer as well? If the bike is used a lot and on wet salty roads the outer cable curve at the RD wears and gets crudded up with rust and dirt meaning shifting performance is compromised. I change my outer cable every six months, it's quick and easy and I buy a couple of metres of outer from the shop and cut them with my Park cable cutter. If you don't have a cutter you could ask the shop to sell you some pieces cut to length.
 
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Tigeranddog

New Member
Did you ask them to change the gear cable inner and outer as well? If the bike is used a lot and on wet salty roads the outer cable curve at the RD wears and gets crudded up with rust and dirt meaning shifting performance is compromised. I change my outer cable every six months, it's quick and easy and I buy a couple of metres of outer from the shop and cut them with my Park cable cutter. If you don't have a cutter you could ask the shop to sell you some pieces cut to length.
As a newbie to cycling I don't understand what you are talking about. This was a brand new cassette & derailleur, and the issue occurred on the first ride with the brand new fittings, so not sure if what you say is actually relevant or not. The bike is used in the mountains in Northern Thailand.
 

Pat "5mph"

A kilogrammicaly challenged woman
Moderator
Location
Glasgow
He did mention when he competed the changeover that 1 gear would give me problems.
Did you ask why that would be?
Did he change the chain also?

This was a brand new cassette & derailleur, and the issue occurred on the first ride with the brand new fittings, so not sure if what you say is actually relevant or not.
@Globalti means did the mechanic change the cables too?
The inner cables (the metal ones) and the outer cables (the plastic sleeve).
It is relevant, because dirt, rust or fraying could be present on the old cables, making gear changes not working right.
 

Globalti

Legendary Member
Correct. People ride around on bikes with under-performing gears because the deterioration of the cables is gradual and they don't realise how bad it has become. Changing the cassette will not improve the shifting if the cable is crudded up or frayed.

Didn't realise you are in Thailand. I've been watching videos of the bloke who entertains elephants by playing them the piano - any of that where you live?
 
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Tigeranddog

New Member
Did you ask why that would be?
Did he change the chain also?


@Globalti means did the mechanic change the cables too?
The inner cables (the metal ones) and the outer cables (the plastic sleeve).
It is relevant, because dirt, rust or fraying could be present on the old cables, making gear changes not working right.
No the cables were not changed. With the previous 11 36 cassette gear changing was smooth & silent as it should be. There was no need to change the chain as it was already a new chain that had only been on the bike 3 months, although I did think with the change to the 11 46 cassette that 1 or 2 links might have to be added, but that was not done. I changed to the 11 46 cassette to help with hill climbing. Most of the gradients around here are mid teens, with plenty in the mid 20's & 30's % wise. I've already encountered one gradient of 41% and another of 47.4% which had to be walked. The reason he gave for having trouble with 1 gear change was because I was going to run an 11s rear derailleur on a 10s cassette with a 10s shifter. That didn't make sense to me as I had read numerous posts before having the change done, where experienced cyclists had made the exact same changes to their setups ( 11s RD, 10s 11 46 cassette with 10s shifter & 3x crank ) and they had absolutely no issues with gear changes at all. In fact most of them had said they initially stayed with their 10s RD and used a goat link but they weren't happy with the shifting, so they went to the 11s RD and had no issues after that. I've been doing some more reading this morning and wonder if it's as simple as cable tension not being correct or perhaps the chain needs to be tightened a smidgeon. As I said the LBS is not a full on bike shop, for him it's just a hobby and his knowledge base is predominantly road bikes. Also in the past he's answered some of my questions incorrectly as his replies differed greatly to what many of the experts have posted in their blogs. There is another bike shop where I live, but he will only service bikes that are purchased from him, so it would be pointless going there as he has already refused to service my gf's bike which was bought elsewhere. As I said in the original post every gear change is smooth as a babies bum except for 8 to 7 & 6 to 7.
 
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Tigeranddog

New Member
Correct. People ride around on bikes with under-performing gears because the deterioration of the cables is gradual and they don't realise how bad it has become. Changing the cassette will not improve the shifting if the cable is crudded up or frayed.

Didn't realise you are in Thailand. I've been watching videos of the bloke who entertains elephants by playing them the piano - any of that where you live?
yes theirs lots of elephant camps around Chiang Mai where similar sorts of things happens, but the piano bit is a rarity.
 

Globalti

Legendary Member
I didn't notice that you wrote: "Also changed Shimano Deore 10s M610 RD to a Shimano 11s" in your first post.

This is the reason for your problem. The cogs on an 11 speed cassette are a tiny bit narrower and closer together than on a 10 speed cassette, meaning that while the derailleur may be set to the correct high and low limit stops and gears 1 and 11 may be perfect, the further the derailleur moves toward the middle of the cassette the less the float on the jockey wheel will be able to accommodate the maladjustment and somewhere it will have to skip a gear.

Derailleurs are not indexed so they can be persuaded to work with a variety of cassettes. What IS indexed is the shifter; which will be spaced accurately to suit 10 speed spacing not the slightly narrower 11 speed spacing. Old-style friction shifters like those found on downtubes or handlebar thumb shifters can accommodate any cassette. because you shift until you find the gear by feel and by sound.
 
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Tigeranddog

New Member
I didn't notice that you wrote: "Also changed Shimano Deore 10s M610 RD to a Shimano 11s" in your first post.

This is the reason for your problem. The cogs on an 11 speed cassette are a tiny bit narrower and closer together than on a 10 speed cassette, meaning that while the derailleur may be set to the correct high and low limit stops and gears 1 and 11 may be perfect, the further the derailleur moves toward the middle of the cassette the less the float on the jockey wheel will be able to accommodate the maladjustment and somewhere it will have to skip a gear.

Derailleurs are not indexed so they can be persuaded to work with a variety of cassettes. What IS indexed is the shifter; which will be spaced accurately to suit 10 speed spacing not the slightly narrower 11 speed spacing. Old-style friction shifters like those found on downtubes or handlebar thumb shifters can accommodate any cassette. because you shift until you find the gear by feel and by sound.
I have to disagree with your answer. I have confirmation from Shimano, a dozen or so bike shops that I'd emailed prior to making the change, and as already stated read numerous forums & blogs where this exact combination of parts has been given the thumbs up. The confirmation from Shimano was the response that convinced me to proceed with this gear set combination. Shimano actually went as far as to say most of the posts on the internet stating that cog spacing on the 10s & 11s cassettes would be an issue were in fact incorrect. They were also quite adamant that the 11s RD would work quite successfully with the 10s cassette & 10s shifter. As I said there are numerous posts in forums and blogs where this exact change has been successfully attained where no shifting issues or gear skipping has been experienced. Further to that I received advice today from the bike shop that actually made this suggested change to me that the ONLY reason for what I'm experiencing is poor setup by my LBS mechanic. They also mentioned that they have done several modifications of this type and no negative feedback has been received. In fact they said one of Thailand's leading MTB racers made these same changes in their shop about 6 months ago and has absolutely no issues with the shifting whatsoever. They have even offered to fix the issue for me for free. Only problem is they are several hundred kms away and I have no way of transporting the bike to them.
 

Globalti

Legendary Member
Why don't they tell you what's wrong then? It can't be anything that's difficult to cure.
 
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Tigeranddog

New Member
Why don't they tell you what's wrong then? It can't be anything that's difficult to cure.
As I said in my last post, the bike shop that suggested these changes to me said it was a setup issue. Watched quite a lot of YouTube videos last night on shifting problems, their possible causes and how to remedy them. One constant became apparent. They all made mention of the kind of issue I was having ( no reference of RD or cassette speeds ) in general, and said that if the derailleur and or the cassette was new then they most likely only needed lubricating. Gave them both a good spray with WD40. Went for a 60km ride today and the problem had disappeared all gear shifts on the rear perfect. However, I began to encounter an issue with the front gear change. I was unable to change up from 2nd to 3rd unless my rear gears were in 9th or 10th gear. Went to the LBS before completing the ride. After a minor tweak to the H screw on the front derailleur and a tweak of the cable tension ALL gears now change perfectly. PROBLEM SOLVED. In closing I would like to thank Pat "5mph" & Globalti for their contributions. Also Globalti I hope your opinion with regards to running an 11s RD with a 10s cassette ( 11 46 ) and 10s shifter ON A MTB have been changed. This change will definately not work with a road bike, but as you can see it works a dream on a MTB when all the minor tweaks are done correctly.
 
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