scirocco

I have a couple of road bikes with Shimano Hollowtech double chainsets (one Ultegra, one 105) and wasn't satisfied with the 39 tooth and 34 tooth gearing that Shimano offer as standard on standard and compact chainsets. The shifting had been perfect, though.

So I've tried out a few "other brand" inner rings, both in the compact and standard sizes. The problem is that the big-to-small shift sometime fails to complete properly. The chain doesn't come off, it doesn't drop between the rings, but it will skate across the teeth of the small ring and fail to drop onto them. The problem is worst when the chainline is across to the right (smaller rear cogs). FD adjustment doesn't seem to make any difference.

I've tried inner rings from FSA, TA Specialites and Stronglight. All the rings are installed properly (facing the correct direction, which varies from brand to brand).

The common factor is that all the rings are branded as 9/10 speed. Are the rings simply too thick to work properly with Shimano 10-speed chains? Or is the problem with the thickness of the lugs of the Shimano chainset?

Anyone else have this problem and find a solution?

joejack951

I've read of this problem before though I never saw any final outcome. I can say with confidence though that the thickness of the rings is not the issue as 9 and 10 speed rings are exactly the same thickness (2.0mm/.079").

Any chance you are using a 9 speed derailler with your 10 speed chain?

scirocco

Thanks for the info. Yes, the bike I'm riding most is using a Tiagra FD, despite being 10-speed. I'm pretty sure, though, that I was having the same problem on the other bike (which does have a 10-speed FD) when I had a non-Shimano ring on that.

I guess I should look in to getting a 10-speed FD for my main bike.

Deanster04

What size rings are you putting on the cranks. If they are smaller than the ones designed for the cranks you might be exceeding the design limits.
I run a campy triple on my touring bike and I have gone smaller on the inner ring from a 30 to a 26 or 28t ring. I can no longer use the 5 smaller cogs on the cassette because of chain rub on the middle ring. Also, I can't shift onto the small chainring when I am on the 2 large cogs on the rear because the chain will fall to the inside. I use a 3rd eye chain saver to prevent the chain from falling to the inside of the crank. I know this probably doesn't help but, my point is when you exceed the design of the component manufacturer you may need to compromise how you use the new setup such as limit the shifting to a different gear combination...experimentation may be your only way of finding a solution. Good luck.

scirocco

I've tried both smaller and larger. 38 tooth FSA on 10-speed 105 regular crank, and 36 tooth Stronglight and 37 tooth TA Specialites on an Ultegra compact crank. All have the same problem to a greater or lesser extent.

I've ordered a 10-speed FD to replace the Tiagra one I've been using, but I'm not convinced that's the problem. The shifting is perfect with standard Shimano 34 tooth or 39 tooth 10-speed inner rings. I think it's something to do with the inner ring centrelines. 10-speed and 9/10-speed rings might well be the same thickness, but if 10-speed ring mountings are offset slightly so that the inner and outer rings are closer together, (which they could be if they're not rated for both 9 and 10-speed) then that could explain the problem.

Time for a Campy 36T 10-speed ring rather than a 9/10 speed ring perhaps?

joejack951

If the ring centers are any differences between 9/10 and 10 speed rings, the difference has to be quite minor and you wouldn't think it would cause the chain to skate. If the 9/10 speed rings were the problem, then any 10 speed chain on a 9/10 speed crank would have this issue. I've never experience anything like it on my Stronglight 9/10 speed crank with Ultegra 10.

Perhaps when mixing chainrings and using the 9 speed derailler, you've somehow created a condition where the chain will drop of the big ring but then get caught in limbo between the ramps on the big ring and the teeth on the little ring. I'm really curious to hear if the 10 speed derailler helps at all.

well biked

I tried a Shimano compact crankset, an R600 designated as nine speed, with an otherwise ten speed Shimano drivetrain the other day. I wouldn't have thought the fact that the cranks were "nine speed" would have made any difference, but the chain did exactly as the OP is describing, not falling far enough down to the small chainring and just sort of hovering over the chainring. In looking at "ten speed" designated cranks, I could see that the gap between the rings was narrower. After installing Shimano "ten speed" 105 cranks, the problem was solved. The problem has to do with how wide the gap is between the chainrings.

HillRider

Hmmm, I'm running a Chorus 10-speed triple set-up and I also changed the 30T granny ring for a 26T. I can shift all the way to the 15T cog (third smallest on my 13x29 cassette) before the rear derailleur runs out of tension and the chain never touches the 42T middle ring.

I haven't tried a middle to granny downshift while in the 26 or 29T cogs so I don't know if it will be a problem but I use a Jump-Stop chain watcher anyway.

BTW, this drivetrain is installed on a Litespeed frame so it's not like I have very long chainstays to reduce the chain angle.

Al1943

I believe in general Campy rings won't fit a Shimano crankset due to Campy's proprietary asymmetrical bolt pattern. Not sure if that is true for all Campy rings though.

Al

Al1943

I've had the same problem with TA Specialties Alize triple chainrings on my wife's bike. I replaced her 9-speed Ultegra triple rings with the Alize 49-39-28 rings. With the chain running on a big angle, the first or second smallest cog and shifting from the big ring to middle ring, the chain would not drop over the teeth of the middle ring. The TA rings teeth with thicker tips than the Shimano rings. To remedy the problem I moved the chainline out with a 2 mm bottom bracket spacer and also filed the backside of the teeth to help the chain fall into place. This worked.

At a later date I tried a Campy 5.9 10-speed chain on the same 9-speed drivetrain and it would not work with the TA chainrings at all. the chain was riding on the tips of the teeth instead of dropping in place. Switching back to the 9-speed D-A chain restored good shifting.

Since these 9-speed TA rings were purchased, TA has introduced 10-speed specific Alize triple chainrings. But I haven't seen them and don't know what the difference is.

https://www.peterwhitecycles.com/chainrings.asp

Al

scirocco

I think this is precisely the problem, however. Thanks to DaveSSS for alerting me to it in another thread.

It appears that when Shimano created 10-speed, they modified the tooth centreline on their 34 and 39 tooth inner rings. The centreline was moved closer towards the outer ring.

On the left in the picture below is a Stronglight 9/10spd 36T inner ring. On the right is a Shimano 9/10 spd 34T inner ring. You can clearly see the difference in the tooth centrelines relative to the flat face of the ring that butts againsts the crank spider arms. The difference is small but enough for the Shimano ring not to suffer the problem I've found.

Don't be fooled by the bevelled tip of the Shimano teeth. The tip of the bevel is not the tooth centreline; the centreline is further to the right.

joejack951, if you're not having the problem, it may be because the Stronglight cranks you are using have thinner spider arms than a Shimano crank, presumably locating the inner and outer rings closer together and avoiding the chain slip problem.

scirocco

Just reporting back, SRAM make a 10-speed-specific 36T ring. This has the teeth offset from the centre of the ring as in the picture of the 34T Shimano ring in the right hand picture above. I've found it works perfectly as a replacement for the 34T Shimano original, with none of the problem of the shift failing to complete.

Moral of the story is, that when replacing 10-speed inner rings on 10-speed Shimano cranks, you need to use 10-speed-specific rings. Using rings that are branded as 9/10 speed will very likely not work well.