Cassette shifting Problem

[Gorgio]

I just replace the 10 speed cassette on my Mountain bike. I decided to go for a largest cog with more teeth for an easier ride uphill.. I increased from 38T to 42T. I also replaced the chain and chainrings at the same time.
When the bike was on the stand it ran through the gears well. I had the following problem when out riding. I had just ridden up a steep hill on the 22T chain ring and the 42T cassette cog. I had changed down to the second largest cog on the cassette and up to the larger 38T chainring.
When I attempted to change up the gears on the cassette, there was no click resistance on the gear shifter and the chain stayed on the second largest cog on the cassette. I shifted a few more times with no change. I then shifted back down to the 22T chainring and the chain jumped down to the fourth smallest cog on the cassette and the shifter was clicking ok again. I changed back up to the 38T chain ring. However I could not change gear from the fourth smallest cog to any of the other smaller cogs on the cassette. The shifter was at its limit. Also noted that when changing down to the largest cassette cog again, there was an additional click on the shifter once the chain was in place on the cog, this appears to move the cable a little but does not affect the chain.
Further info is that the 'B' screw is at its limit for getting the required clearance between chain and cog.
Any suggestions. The whole of the chain drive system is Shimano. The 10 speed 42T-11T cassette is according to Shimano is compliant with all Shimano 10 speed systems.

[Painkiller]

(06-25-2025, 06:16 PM)Gorgio Wrote:  I just replace the 10 speed cassette on my Mountain bike. I decided to go for a largest cog with more teeth for an easier ride uphill.. I increased from 38T to 42T. I also replaced the chain and chainrings at the same time.
When the bike was on the stand it ran through the gears well. I had the following problem when out riding. I had just ridden up a steep hill on the 22T chain ring and the 42T cassette cog. I had changed down to the second largest cog on the cassette and up to the larger 38T chainring.
When I attempted to change up the gears on the cassette, there was no click resistance on the gear shifter and the chain stayed on the second largest cog on the cassette. I shifted a few more times with no change. I then shifted back down to the 22T chainring and the chain jumped down to the fourth smallest cog on the cassette and the shifter was clicking ok again. I changed back up to the 38T chain ring. However I could not change gear from the fourth smallest cog to any of the other smaller cogs on the cassette. The shifter was at its limit. Also noted that when changing down to the largest cassette cog again, there was an additional click on the shifter once the chain was in place on the cog, this appears to move the cable a little but does not affect the chain.
Further info is that the 'B' screw is at its limit for getting the required clearance between chain and cog.
Any suggestions. The whole of the chain drive system is Shimano. The 10 speed 42T-11T cassette is according to Shimano is compliant with all Shimano 10 speed systems.

the best way to duplicate how it works in a stand vs actually riding it would be to use a trainer with resistance, it sounds kinda like a sticky shifter, showing pics of what you have may help

[ReapThaWhirlwind]

From the sounds of it, you will want to check the limit screw first and the B screw second.

Unscrew the low limit screw all the way and try to ascend the gears. That will tell you if it's the limit screw. When you get into the top gear, you will want to screw it back in until it's snug tension with the hammer inside. That should set the limit screw properly.

Try the same for the B screw, and unscrew it as much as possible until there's just little left. Then check the gears.

Before you do all this, you might want to adjust the cable tension. Undo the cable, dial the barrel adjuster all the way in on the rear derailleur. Then lightly pull the cable just to remove the most absolute basic slack from the line, and re-fasten the cable to the bolt. Begin to dial the adjuster out little by little and shift up to check the indexing.Keep doing this until you can ascend all the way and back down with no issues.

Report back and let me know the update.

[Gorgio]

(07-02-2025, 01:06 AM)ReapThaWhirlwind Wrote:  From the sounds of it, you will want to check the limit screw first and the B screw second.

Unscrew the low limit screw all the way and try to ascend the gears. That will tell you if it's the limit screw. When you get into the top gear, you will want to screw it back in until it's snug tension with the hammer inside. That should set the limit screw properly.

Try the same for the B screw, and unscrew it as much as possible until there's just little left. Then check the gears.

Before you do all this, you might want to adjust the cable tension. Undo the cable, dial the barrel adjuster all the way in on the rear derailleur. Then lightly pull the cable just to remove the most absolute basic slack from the line, and re-fasten the cable to the bolt. Begin to dial the adjuster out little by little and shift up to check the indexing.Keep doing this until you can ascend all the way and back down with no issues.

Report back and let me know the update.

Hey thanks for that. The problem is fixed, however I will keep your useful info for the future.
Regards

[Jesper]

@Giorgio

Let the masses know what solved the problem for others to reference if they have a similar situation.

[JJMarsh]

(06-25-2025, 06:16 PM)Gorgio Wrote:  I just replace the 10 speed cassette on my Mountain bike. I decided to go for a largest cog with more teeth for an easier ride uphill.. I increased from 38T to 42T. I also replaced the chain and chainrings at the same time.
When the bike was on the stand it ran through the gears well. I had the following problem when out riding. I had just ridden up a steep hill on the 22T chain ring and the 42T cassette cog. I had changed down to the second largest cog on the cassette and up to the larger 38T chainring.
When I attempted to change up the gears on the cassette, there was no click resistance on the gear shifter and the chain stayed on the second largest cog on the cassette. I shifted a few more times with no change. I then shifted back down to the 22T chainring and the chain jumped down to the fourth smallest cog on the cassette and the shifter was clicking ok again. I changed back up to the 38T chain ring. However I could not change gear from the fourth smallest cog to any of the other smaller cogs on the cassette. The shifter was at its limit. Also noted that when changing down to the largest cassette cog again, there was an additional click on the shifter once the chain was in place on the cog, this appears to move the cable a little but does not affect the chain.
Further info is that the 'B' screw is at its limit for getting the required clearance between chain and cog.
Any suggestions. The whole of the chain drive system is Shimano. The 10 speed 42T-11T cassette is according to Shimano is compliant with all Shimano 10 speed systems.

Classic chain length and derailleur capacity issue. That bigger 42T cog is likely too much for your current derailleur to handle, which is why the B-screw is maxed out and the shifting is messy. You'll probably need a derailleur hanger extender or a new derailleur designed for a larger cassette. Also, double-check that the new chain is long enough.