9 speed triple shifter and 10-speed front derailleur compatibility

[Gatekeeper]

Thanks for approving my registration Relja. This is my first post in this forum. My name's Jose and I´m writing from Spain. I find your Youtube videos really interesting and educational, which made me sign up for this forum.

I´m writing because I´d like to bring to your attention a problem I have mix matching Shimano mountain components.

To keep the story short, I´d rather not go into detail as to why I´m using this setup, but the thing is I´ve ended up using a mix of 9 and 10 speed triple mountain drivetrain on an old 26” MTB, in particular a Rockrider 500 from Decathlon.

As for the rear setup, I´m running a 9-speed XT-M770 right shifter with a 9-speed XT-M770 cassette and a 9-speed Deore rear derailleur, with no problems at all.

The problem comes with the front setup. I originally intended to keep everything 9 speed, but I ended up installing a Shimano Deore 10-speed FC-M6000 triple crankset because of the smaller chainrings (40-32-22). I then installed a 10-speed chain because according to Shimano this crankset has to be used with an HG-X chain. (I don’t know if a 9-speed chain would work just as well). Nevertheless, this combination works well with the rear setup and I don’t have any problems changing gears at the back.

When choosing a front derailleur, I found that most old 9-speed ones were intended for larger chainrings, so in the end I went for a 10-speed Deore FD-M610 front derailleur, which is supposed to be valid for a 42/40 large chainring with a 18-tooth difference.

Finally, in order to use similar shifters, I decided to install the left XT-M770 9-speed triple shifter thinking it would be compatible with the 10-speed front derailleur. And here comes the problem.

Funnily, when you initially check the front setup, it seems to work beautifully and there are no issues at all. When you change chainrings in a quick succession everything works as it should. The problem comes when you leave the chain on the middle chainring for a while. When you then try to change to the smallest chainring, the left trigger initially doesn’t work. The lever travels to the end but with no resistance and not clicking. However, after you’ve done this once, the lever goes back to normal and when pressing it a second time it engages the cable and shifts to the smallest chainring. I hope I´m making myself clear enough. This doesn’t happen when changing from the largest chainring into the middle one. I´ve check the cable tension and it’s tight enough and not slack.

I replaced the left shifter with an identical one and kept having the same problem, so I´m pretty sure the shifter works perfectly fine. I also replaced the front derailleur with another 10-speed one, an FC-T6000 front derailleur. This is intended for trekking and larger chainrings, but it was the one I had at hand and I just wanted to make sure the original front derailleur wasn’t the problem. Same thing and same issue.

So I´m now wondering whether the cable pull ratio is different between Shimano mountain 9 and 10 speeds.

I´ve found a 9-speed front derailleur which might do the job, an Acera FD-M3000 3x9 intended for 40-32-22 chainrings, but I´d rather use a better one like the 10-speed Deore. I guess I could also change the front left shifter and use a 10-speed one, but I´d like to use similar-looking shifters.

Sorry for making the story so long. Any answers would be much appreciated.​

 

[BikeGremlin]

Thanks for approving my registration Relja. This is my first post in this forum. My name's Jose and I´m writing from Spain. I find your Youtube videos really interesting and educational, which made me sign up for this forum.

I´m writing because I´d like to bring to your attention a problem I have mix matching Shimano mountain components.

To keep the story short, I´d rather not go into detail as to why I´m using this setup, but the thing is I´ve ended up using a mix of 9 and 10 speed triple mountain drivetrain on an old 26” MTB, in particular a Rockrider 500 from Decathlon.

As for the rear setup, I´m running a 9-speed XT-M770 right shifter with a 9-speed XT-M770 cassette and a 9-speed Deore rear derailleur, with no problems at all.

The problem comes with the front setup. I originally intended to keep everything 9 speed, but I ended up installing a Shimano Deore 10-speed FC-M6000 triple crankset because of the smaller chainrings (40-32-22). I then installed a 10-speed chain because according to Shimano this crankset has to be used with an HG-X chain. (I don’t know if a 9-speed chain would work just as well). Nevertheless, this combination works well with the rear setup and I don’t have any problems changing gears at the back.

When choosing a front derailleur, I found that most old 9-speed ones were intended for larger chainrings, so in the end I went for a 10-speed Deore FD-M610 front derailleur, which is supposed to be valid for a 42/40 large chainring with a 18-tooth difference.

Finally, in order to use similar shifters, I decided to install the left XT-M770 9-speed triple shifter thinking it would be compatible with the 10-speed front derailleur. And here comes the problem.

Funnily, when you initially check the front setup, it seems to work beautifully and there are no issues at all. When you change chainrings in a quick succession everything works as it should. The problem comes when you leave the chain on the middle chainring for a while. When you then try to change to the smallest chainring, the left trigger initially doesn’t work. The lever travels to the end but with no resistance and not clicking. However, after you’ve done this once, the lever goes back to normal and when pressing it a second time it engages the cable and shifts to the smallest chainring. I hope I´m making myself clear enough. This doesn’t happen when changing from the largest chainring into the middle one. I´ve check the cable tension and it’s tight enough and not slack.

I replaced the left shifter with an identical one and kept having the same problem, so I´m pretty sure the shifter works perfectly fine. I also replaced the front derailleur with another 10-speed one, an FC-T6000 front derailleur. This is intended for trekking and larger chainrings, but it was the one I had at hand and I just wanted to make sure the original front derailleur wasn’t the problem. Same thing and same issue.

So I´m now wondering whether the cable pull ratio is different between Shimano mountain 9 and 10 speeds.

I´ve found a 9-speed front derailleur which might do the job, an Acera FD-M3000 3x9 intended for 40-32-22 chainrings, but I´d rather use a better one like the 10-speed Deore. I guess I could also change the front left shifter and use a 10-speed one, but I´d like to use similar-looking shifters.

Sorry for making the story so long. Any answers would be much appreciated.​

Hi and welcome to the forum,

I'm not really sure what could be causing the problem. The confusing part is that there seems to be no chain rub (correct me if I'm wrong) and poor shifting - when the shifter clicks. The problem is when the shifter doesn't click.

I'd take a look at the position of the chain, chainring, and FD cage when it normally shifts to the middle ring - then compare that to their position when the chain has been on the middle chainring "for a while."

Relja

 

[Gatekeeper]

Hi!

Thanks a lot for your quick reply.

Exactly. No rubbing or poor shifting when it clicks. When initially setting up the whole drivetrain, everything works as it should. I install and adjust the front derailleur so that there is no chain rub. Once finished, when testing everthing on the work stand, you can shift between all the gears and chainrings no problem. The front trigger works fine and you can change front the smallest to the biggest chainring and back without a problem.

But as I explained, after leaving the chain on the middle chainring and not changing rings for while, when you try to change into the smallest chainring that's when the problem occurs. However, the cable is not slack and the front derailleur seems to be exactly in the same position as before. No chain rub and no apparent displacement of the front derailleur due to a change in cable tension. I know because for testing purposes I leave the chain on the largest cog at the back (where the distance between the chain and the inner plate of the front derailleur is the smallest) and that distance doesn't change at all even when I get the problem. But for some unknown reason the shifter doesn't click or engage the cable the first time you press it and you need to press it a second time. Once you've "solved" it, everything works normally again if you keep changing chainrings. The moment you leave the chain on the middle chainring for a while is when you get the problem again. No idea why.

My next try is going to be changing the inner cable and housing. I can´t think of anything else. Or maybe I have a gremlin in the shifter. At least I wanted to make sure there shouldn't be a compatibility problem between the 9-speed shifter and the 10-speed derailleur.

Thank a lot once again.

 

[BikeGremlin]

Hi!

Thanks a lot for your quick reply.

Exactly. No rubbing or poor shifting when it clicks. When initially setting up the whole drivetrain, everything works as it should. I install and adjust the front derailleur so that there is no chain rub. Once finished, when testing everthing on the work stand, you can shift between all the gears and chainrings no problem. The front trigger works fine and you can change front the smallest to the biggest chainring and back without a problem.

But as I explained, after leaving the chain on the middle chainring and not changing rings for while, when you try to change into the smallest chainring that's when the problem occurs. However, the cable is not slack and the front derailleur seems to be exactly in the same position as before. No chain rub and no apparent displacement of the front derailleur due to a change in cable tension. I know because for testing purposes I leave the chain on the largest cog at the back (where the distance between the chain and the inner plate of the front derailleur is the smallest) and that distance doesn't change at all even when I get the problem. But for some unknown reason the shifter doesn't click or engage the cable the first time you press it and you need to press it a second time. Once you've "solved" it, everything works normally again if you keep changing chainrings. The moment you leave the chain on the middle chainring for a while is when you get the problem again. No idea why.

My next try is going to be changing the inner cable and housing. I can´t think of anything else. Or maybe I have a gremlin in the shifter. At least I wanted to make sure there shouldn't be a compatibility problem between the 9-speed shifter and the 10-speed derailleur.

Thank a lot once again.

No problem - just sorry that I can't help with the solution.

Another thought:

Is it very cold, and does the problem occur only when you take the bike outside (away from the bike stand)?

It's a wild guess, but I'm considering hardened grease inside the shifter. Yes, the front derailleur cable tension is high compared to the rear derailleur, and the front shifter springs should not be so weak for that to be a problem, but I haven't got any other ideas at the moment.

 

[Gatekeeper]

No problem - just sorry that I can't help with the solution.

Another thought:

Is it very cold, and does the problem occur only when you take the bike outside (away from the bike stand)?

It's a wild guess, but I'm considering hardened grease inside the shifter. Yes, the front derailleur cable tension is high compared to the rear derailleur, and the front shifter springs should not be so weak for that to be a problem, but I haven't got any other ideas at the moment.

Actually yes. You may be right about it, because I always had the feeling it gets worse when riding in the cold, but I thought it made no sense and that could not be the reason. I ride other bikes in similar temperatures and I don't have this problem. Maybe the grease in this particular shifter is somehow more sensitive to the cold or has hardened over the years, because the XT M770 shifter is a rather old model.

It's true the problem has worsened in recent months when it's got colder, that's a fact, but it also happens when the bike is left at home overnight in room temperatures of about 18 degrees celsius, so I don't think that's cold enough for the grease to harden. But there's no doubt the problem worsens in the cold, so I´ll take it into account. Now that I know it's not a compatibility issue, I'll explore other alternatives. You´ve been really helpful Relja. Thanks a lot. I´ll keep you posted if I find a solution.

 

[BikeGremlin]

Actually yes. You may be right about it, because I always had the feeling it gets worse when riding in the cold, but I thought it made no sense and that could not be the reason. I ride other bikes in similar temperatures and I don't have this problem. Maybe the grease in this particular shifter is somehow more sensitive to the cold or has hardened over the years, because the XT M770 shifter is a rather old model.

It's true the problem has worsened in recent months when it's got colder, that's a fact, but it also happens when the bike is left at home overnight in room temperatures of about 18 degrees celsius, so I don't think that's cold enough for the grease to harden. But there's no doubt the problem worsens in the cold, so I´ll take it into account. Now that I know it's not a compatibility issue, I'll explore other alternatives. You´ve been really helpful Relja. Thanks a lot. I´ll keep you posted if I find a solution.

The not clicking part after some time in a certain gear (if everything stays as it was - as you explained) leads me to suspect the shifter itself. A splash of WD40 inside (to wash out any stuck gunk) may help with that.

Slow shifting or chain rub would lead me to suspect incompatibility, but a shifter failing to click just because it stayed in a gear for a while (and clicking fine when shifting more rapidly) doesn't sound like a compatibility issue (technically, a 100% safe bet would be to get a 3x9 shifter, cranks etc, of course).

 

[Gatekeeper]

Thanks a lot once again. I´ll try the WD40 solution following your advice. It might be as simple as that after all. I can always install the Acera 9-speed front derailleur or replace the shifter with a 10-speed one, but I´d like to keep it to match the right one and because this particular model allows you to remove the 3-speed gear indicator, which was not a common feature with older Shimano shifters.

 

[Gatekeeper]

My dear Relja,

I´m writing once again to update you on the situation and to tell you that I finally managed to solve the problem thanks to your advice.

I removed the cover of the shifter and quickly realised what the problem was. The internal mechanism and spring moved no problem from the highest gear to the middle gear. However, when shifting from the middle gear to the lowest gear, the mechanism was quite "lazy" and seemed to move more slowly than it should, probably due to some sort of friction. A splash of WD40 inside did wonders and brought the shifter back to normal operation.

Thanks a lot once again. I was so focused on the compatibility issue that I would never have thought of this simple solution. Even installing a 9-speed front derailleur wouldn't have solved the problem.

Keep up the good work.

Jose