# Chain rubbing inside of outer chainring



## lemmy999 (Apr 6, 2004)

I have a Strongligth Pulsion 50/34 compact crankset with a 108mm Token ISIS BB. When I am in the outer 3 cogs in the rear, the chain rubs against the inner surface of the big ring. I have put a 1mm spacer to offset the crank 1mm to the drive side and this made it only very slightly rub on the 3rd cog. I have had this problem for a while and was wondering what is the best solution:

1) try a 36 chainring. I am sure this helps since it will move the point the chain leaves the inner wring up by a about 4mm, but I am not sure how much of a difference it will make. 

2) go from a 108 BB with a 1mm spacer on the right to a 113BB with no spacer This will move the chainline out another 1.5 mm. If it is just rubbing at the 3rd cog, and the 2nd cog is 4mm further out from the bike than the 3rd, then the chainrings would have to move out 4mm for the chain to only be slightly rubbing for the 2nd cog. So I don't think it would help that much, but could make things worse for the bigger cogs when in the big ring

3) put spacers in for the big ring so that there is a larger space between the big and small ring. I think this would work best, but not sure it is a good idea on the Pulsion. The fairly small carbon tabs that are sandwiched between the two rings might not be made to have the force all on a small area (where the spacer is). Right now the chainring surface is flat against the entire tab. 

thanks for any suggestions.


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## cyclust (Sep 8, 2004)

If you were to put a spacer between the chainring and the spider, you'd likely create too much space between the chainrings, and your chain could jam between the rings. Is your entire drivetrain 10 speed specific? Many aftermarket cranks are for 9 or 10 speed. 9 speed chains are a bit wider than 10 speed, so perhaps if you are running 9 speed, you may have to switch to 10 speed for optimum results. There are a lot of variable that could cause your problem, but I'd start with the chain, and make sure it is the correct width.


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## lemmy999 (Apr 6, 2004)

Good point. I have a 9 speed cassette with a 9 speed chain. However the crank is for 9 or 10 speed.


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## FatTireFred (Jan 31, 2005)

that happens when you crosschain, common issue. and as you've surmised, messing w/ chainline/bb spindle length presents other issues


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## lemmy999 (Apr 6, 2004)

That isn't always true. I had an Ultegra 53/39 and it didn't do it even when running small ring and small cog (not that I did this while riding, this was in the stand). I don't really consider small ring and 3rd cog as crosschain anyway. But the biggest reason I don't like what is happening is that I am sure that if I screw up and do go to small ring and cog 1 or 2, then I just want some noise and excessive wear to happen, I don't want the chain to get caught by the shift pins/ramps and pulled and up jammed, and possibly have things broken.


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## suprcivic (Apr 10, 2009)

personally, i like to tinker. i would try the longer BB and see if it works. buy it at performance or REI. that way, if you have chainline issues, you can return it.

i've had that issue before. fortunately, i had an external BB with spacers on the non-drive side, so all i had to do is switch the spacers over to the drive side. it fixed it and i had no chainline issues.

definitely don't put spacers on the big chainring.


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## FatTireFred (Jan 31, 2005)

lemmy999 said:


> That isn't always true. I had an Ultegra 53/39 and it didn't do it even when running small ring and small cog (not that I did this while riding, this was in the stand). I don't really consider small ring and 3rd cog as crosschain anyway. But the biggest reason I don't like what is happening is that I am sure that if I screw up and do go to small ring and cog 1 or 2, then I just want some noise and excessive wear to happen, I don't want the chain to get caught by the shift pins/ramps and pulled and up jammed, and possibly have things broken.




common issue WITH COMPACT CRANKS


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## lemmy999 (Apr 6, 2004)

I have always heard this is an issue with compacts as well. However I don't really understand why. If you measure the distance from where the chain takes off from the inner ring to the point where the chain clears the edge of the outer ring, you will find that a 53/39 is a longer distance (and should be worse) than a 50/34 or a 50/36. 

http://www.ssfweb.info/chainring.pdf


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## Drew Eckhardt (Nov 11, 2009)

cyclust said:


> If you were to put a spacer between the chainring and the spider, you'd likely create too much space between the chainrings, and your chain could jam between the rings.


Depends on the crank set.

My FSA compact rubbed with my Campagnolo 9-speed setup.

I found that the chain rings on my FSA compact were closer than Campagnolo specified for their 10-speed cranks which are .4mm tighter than 9 speed cranks.

Adding .4mm got me a couple cogs with no effect on shifting; 1.0mm made everything usable but shifted slower; I don't recall if I left that or went to .8mm.


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## Drew Eckhardt (Nov 11, 2009)

lemmy999 said:


> Good point. I have a 9 speed cassette with a 9 speed chain. However the crank is for 9 or 10 speed.


Several companies (Wheels Manufacturing, LeTour) sell .6mm spacers specifically for making 10-speed cranks work with 9-speed chains and cogs.


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## lemmy999 (Apr 6, 2004)

So you were using spacers to adjust the spacing between your inner and outer chainrings? I don't know if I can do that on the crankset I have. Also, I have read that the spacing on the Stronglight Pulsion is a little more than it is for the Shimano. The only reason I can figure that I have having this rubbing is that possibly the Stronglight chainrings are a little thicker in the body (not where the teeth are).


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## Drew Eckhardt (Nov 11, 2009)

lemmy999 said:


> So you were using spacers to adjust the spacing between your inner and outer chainrings?


Yup.



> I don't know if I can do that on the crankset I have.


Sure you can. The spacers go around the chain ring bolts and either move the outer ring out or inner ring in.



> Also, I have read that the spacing on the Stronglight Pulsion is a little more than it is for the Shimano. The only reason I can figure that I have having this rubbing is that possibly the Stronglight chainrings are a little thicker in the body (not where the teeth are).


Measure the thickness of the crank spider where it mates to the rings and chain rings with your calipers (if you don't yet have a pair, places like harbor freight have inexpensive dial calipers). Add the spider thickness to half of each chain ring's thickness and compare the total to published "standard" numbers.

Or compare the spider thickness where it meets the rings with your old crank.


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## lemmy999 (Apr 6, 2004)

Thanks. 

I understand how the spacers work, I am just not sure it is ok to use with the carbon spider on my crank. Right now the flat tabs on the spider are sandwiched between moderate sized flat sections on both chainrings. It seems that if I put a spacer in there, all forces would be concentrated on a much smaller area on the carbon tab on the spider. Maybe it wouldn't matter though...not sure.


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## RHankey (Sep 7, 2007)

It is a common problem with compact cranks, and made worse if you have short chain stays.

Unless you are using a 10sp crank with a 8 or 9sp chain/cassette, I would not put spacers between the chain rings. Spacing out the chain rings will cause the chain to shift between the chain rings, and can also cause false neutrals.


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## lemmy999 (Apr 6, 2004)

I can understand short chain stays causing this problem, but even though I admit I hear of more people with compacts having this problem, it just doesn't make sense. Compacts should have less of a problem with it since there is a shorter distance between the chain leaivng the middle ring clearing the big ring.


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## RHankey (Sep 7, 2007)

Compacts per-se are not as much the problem as the size difference (or ratio) between that of the big and small chain rings. The ratio is usually greater between the large/small rings of compact cranks than it is with standard cranks.

Your 50T/36T compact would be equicvelent to running a 53T/36T current standard size crank (smaller ring being 3T smaller than the normal 39T). A 53T/36T standard crank would have rubbing issues too.

If you are set on keeping your 50T, you should be able to eliminate your rubbing by changing your inner ring to a 37T or larger, which would result in a similar ratio as a stock 53T/39T standard cranks, but still a larger ratio than the older stock 52T/42T standard cranks.


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## FatTireFred (Jan 31, 2005)

RHankey said:


> Your 50T/36T compact would be equicvelent to running a 53T/36T current standard size crank (smaller ring being 3T smaller than the normal 39T).




huh?
.


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## RHankey (Sep 7, 2007)

FatTireFred said:


> huh?
> .


Oops. Meant to write that a 50T/36T is equivelent to a 53T/38T (1T smaller ring than a current standard crank).

As I previously wrote, the OP should be able to eliminate rubbing with a 37T or larger small ring.

Thanks for catching that error.


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## FatTireFred (Jan 31, 2005)

RHankey said:


> Oops. Meant to write that a 50T/36T is equivelent to a 53T/38T (1T smaller ring than a current standard crank).
> 
> As I previously wrote, the OP should be able to eliminate rubbing with a 37T or larger small ring.
> 
> Thanks for catching that error.




who makes a 37t x 5 bolt x 110bcd chainring?


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## Drew Eckhardt (Nov 11, 2009)

lemmy999 said:


> Thanks.
> 
> I understand how the spacers work, I am just not sure it is ok to use with the carbon spider on my crank. Right now the flat tabs on the spider are sandwiched between moderate sized flat sections on both chainrings. It seems that if I put a spacer in there, all forces would be concentrated on a much smaller area on the carbon tab on the spider. Maybe it wouldn't matter though...not sure.


I've had the spacers on my FSA Carbon Pro Compact (the first one, with the separate carbon fiber spider) ISIS cranks for seven years without issue. That's a data point, not necessarily an endorsement.

If you were really worried you could just trim some shim stock down to size with tin snips and preserve the contact area.


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## lemmy999 (Apr 6, 2004)

Drew Eckhardt said:


> I've had the spacers on my FSA Carbon Pro Compact (the first one, with the separate carbon fiber spider) ISIS cranks for seven years without issue. That's a data point, not necessarily an endorsement.
> 
> If you were really worried you could just trim some shim stock down to size with tin snips and preserve the contact area.



I have heard the spacing is usually around 5mm for between rings. I measured mine as best as I could and it seems that the spider tab thickness is 3.5mm. The outer ring is around 3.6mm and the inner ring around 3.3mm. So that would be a spacing of around 7mm. The actual gap between the chainrings is 3.5mm and so I guess I could put a 0.6mm spacer for the large chainring and the 10sp chain (5.88mm wide) would still should not be able to wedge down between.

Stronglight claims that a 108BB with this crankset should give 43.5mm chainline. I have a spacer on the right side (1mm) so I should have a 44.5mm chainline. However the total thickness of both chainrings and the spider is ~10.5mm. I measured from the middle of the seat tube to the outside of the chainring and it was 46.25mm. If I then subtract 10.5/2 to get to the middle of the rings, that would put my chainline extremely low at ~41mm. I am sure I could be off 1mm. But that still leaves me way under the recommended 43.5. I measured the rear and it is around 42.2m (130/2 - 22.8). This is making me wonder if I shouldn't try the 113mm BB. Maybe this problem could be caused by the BB not really being as wide as it claims..or possibly it allows the crank to go up on the spindle more than it should.


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## RHankey (Sep 7, 2007)

lemmy999 said:


> I have heard the spacing is usually around 5mm for between rings. I measured mine as best as I could and it seems that the spider tab thickness is 3.5mm. The outer ring is around 3.6mm and the inner ring around 3.3mm. So that would be a spacing of around 7mm. The actual gap between the chainrings is 3.5mm and so I guess I could put a 0.6mm spacer for the large chainring and the 10sp chain (5.88mm wide) would still should not be able to wedge down between.
> 
> Stronglight claims that a 108BB with this crankset should give 43.5mm chainline. I have a spacer on the right side (1mm) so I should have a 44.5mm chainline. However the total thickness of both chainrings and the spider is ~10.5mm. I measured from the middle of the seat tube to the outside of the chainring and it was 46.25mm. If I then subtract 10.5/2 to get to the middle of the rings, that would put my chainline extremely low at ~41mm. I am sure I could be off 1mm. But that still leaves me way under the recommended 43.5. I measured the rear and it is around 42.2m (130/2 - 22.8). This is making me wonder if I shouldn't try the 113mm BB. Maybe this problem could be caused by the BB not really being as wide as it claims..or possibly it allows the crank to go up on the spindle more than it should.


Having the chain get wedged between the chain rings is only one risk if the chain ring spacing is too great. The other problem is when the spacing is wider than it should be but not wide enough to jamb the chain, in which case one side of chain plates will ride on the top of the inner chain ring teeth. This latter issue is what causes very annoying false neutrals.

In short, if all the driveline components are correctly matched, then you do not want to be adding spacers beween the chainrings. Spacers are only really a viable option if using lets say a 10sp crank with an 8sp chain and drivetrain.


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## ericm979 (Jun 26, 2005)

FatTireFred said:


> who makes a 37t x 5 bolt x 110bcd chainring?


TA makes one. You can get it from Harris.


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## Drew Eckhardt (Nov 11, 2009)

RHankey said:


> In short, if all the driveline components are correctly matched, then you do not want to be adding spacers beween the chainrings. Spacers are only really a viable option if using lets say a 10sp crank with an 8sp chain and drivetrain.


Contemporary 10 speed compatible cranks aren't correctly matched to 9 speed drive trains like lemmy999's.

For example:

Campagnolo 9 speed chains are 6.8mm wide. Campagnolo 10 speed chains were initially 6.1mm wide and have shrunk to 5.9mm. The chain rings need to be .35 - .45mm closer for the same clearances, and Campagnolo machined .4mm off the back side of their 10 speed outer rings.

.4mm restores stock spacing. 

Photos at Branford Bike:
http://branfordbike.com/articles/chainrings-pg68.htm

Some cranksets have even less clearance between the "9 and 10 speed compatible" rings than Campagnolo.


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## mikemayf (Sep 29, 2007)

Before adding spacers, etc., have you actually checked the chainline? Also, have you checked frame alignment? Might be a good idea to know what problem you're trying to fix.


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## lemmy999 (Apr 6, 2004)

mikemayf said:


> Before adding spacers, etc., have you actually checked the chainline? Also, have you checked frame alignment? Might be a good idea to know what problem you're trying to fix.


The chainline with this BB and crank is supposed to be 43.5. However I found it to be less than that. More like 41-42. Also, the Q factor was less than it should have been. It was suposed to be 148mm and I measured it at 146mm. It was almost like the crank arms were further on the BB spindle than they were supposed to be. (This is ISIS so it wasn't like I had over torqued a square taper). 

I don't think it is a frame problem. I had a Klein Quantum Race that was fine with the old crank, then when I went to this crank/BB it had the problem. Then when I changed to a new Lynskey Ti frame, I still had the problem. 

However it seems I may have finally fixed it. I thought I had put a 1mm spacer on the drive side of the BB in the past, but I had not. I did that and installed a Dura-Ace 7900 (10sp) chain. That chain is about 0.8mm narrower than my old one. It now rubs slightly in the outer cog (but not enough to pull the chain up like it was before) and not at all in the 2nd or 3rd cog.


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## FatTireFred (Jan 31, 2005)

is the spindle length correct/accurate?


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## lemmy999 (Apr 6, 2004)

Yes, I had wondered the same thing, so that is why I took everything off to check. It was 108.2mm. 

However the Token BB I have on there is a little odd. The spindle on most ISIS BB seems to have a definite edge that stops the crank from being pressed on too far. Like this:










But the end of the splines on the Token are a little more rounded instead of having a definite stopping point for the crank arms.


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## FatTireFred (Jan 31, 2005)

the few ISIS BBs I've used were like the token


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## Visitor302 (Aug 6, 2005)

Sounds like a cross chain thing to me...
Instead of using the lower 3 cogs, go to the next chainring, then go to the top cogs. the gear ratios should be close.


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## lemmy999 (Apr 6, 2004)

If everything is perfect then the mid point between the two rings should line up with the #5 cog in the rear (I have a 9 speed cassette). My chainrings are spaced 3.5mm on each side of the mid point (7mm spacing between rings). So the plane of the small ring is 3.5mm inboard of the #5 cog. Rear cogs are about 4mm spacing I think. So the #7 cog (where I am starting to get chainring rub) is actually 1mm closer to the plane of the small ring (so it is LESS cross chain) than the #1 (or largest) cog. So if #7 is considered "cross chain", then the lowest gear on the bike is even more cross chained.


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## Touch0Gray (May 29, 2003)

Branford bikes sell .4mm and .6mm shims I believe. They are specifically for using a Campy 10 spd crankset with a 9 speed rear cogset. It works beautifully.


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## DrSmile (Jul 22, 2006)

I had a similar problem with Stronglight chainrings on a compact Campy chainset (all 10 spd). The spacing is definitely too small and the chain will catch on the larger ring on the lowest 4 gears. I added 0.6 mm spacers on the inside chainring (on a Campy chainset you can't add it to the outside chainring because of the arm bolt) and it now only rubs on the last 2 gears which is pretty normal. The chainline seems fine.


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## Al1943 (Jun 23, 2003)

I would try a 2 mm bottom bracket spacer and a 36 tooth inside chainring.
Both are easy to chainge and you won't even have to break the chain.


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## AndreyT (Dec 1, 2011)

I have a pretty much new 2012 Specialized TriCross Elite with 50/34 in front and 10-speed 11-32 in the rear. The chain has always been rubbing the big ring when crosschained. It is not really noticeable when riding and the chain does not catch anything (the inner surface of the outer ring is specifically designed for this), but the grease marks are there on the inner side of the ring.

A more important question would be: why do you care? This rubbing is perfectly normal. Moreover, this only happens when under severe crosschaining, which is not even remotely a normal riding configuration. I.e. it shouldn't really concern anyone at all. Are you really riding the small ring with "3 outer cogs" or were you simply playing with the shifters and noticed the rub?


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## Tucson_2011 (Nov 10, 2011)

DrSmile said:


> I had a similar problem with Stronglight chainrings on a compact Campy chainset (all 10 spd). The spacing is definitely too small and the chain will catch on the larger ring on the lowest 4 gears. I added 0.6 mm spacers on the inside chainring (on a Campy chainset you can't add it to the outside chainring because of the arm bolt) and it now only rubs on the last 2 gears which is pretty normal. The chainline seems fine.


I tried this on mine (Stronglite cranks/Campy 10 cogs/SRAM rings/10 speed SRAM chain) and had to decide whether the occasional dropping in between the front rings was worse than having the rub on the last two. I had to take out the .? mm spacers and now it rubs on the last two gears again, which as you say, is pretty normal, but it won't get caught in the front anymore. Crosschain frankenstein, I know,... but it works now. 30 speed touring bike, I am not in any races. Obviously, with so many gears and three rings the chainline is all over the place, but after many efforts on just the right wheel dish, and trying several different front rings it is dialed for the primary gears I use. And my criterion for stopping the experiment was for the middle ring to index all 10 of the rear cogs with no rubbing anywhere.


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## Drew Eckhardt (Nov 11, 2009)

AndreyT said:


> A more important question would be: why do you care? This rubbing is perfectly normal.


It needn't be. I don't have any rubbing in any gear combinations.



> Moreover, this only happens when under severe crosschaining, which is not even remotely a normal riding configuration. I.e. it shouldn't really concern anyone at all.


With a tight cassette and compact double instead of a triple it's completely normal.

Consider 50-34 x 13-14-15-16-17-18-19-21-23. Eschewing the fully cross-chained combinations the only overlap is in 50x21 and 34x14. With 10 cogs and a more traditional 12 first position cog 34x13 would provide a gear like 50x19 but still produce a lot of riding in that configuration.



> Are you really riding the small ring with "3 outer cogs"


All the time with a slight head-wind, false flat headed up-hill, or rest day.

Chain wear isn't any different than with a 40 ring which makes a more central 16-17 cog an ideal choice for 17-19 MPH cruising speeds.


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## cxwrench (Nov 9, 2004)

Drew Eckhardt said:


> It needn't be. I don't have any rubbing in any gear combinations.


it might not make noise, but the likelihood of it rubbing is high enough that both SRAM and Shimano make sure that it's spelled out clearly in their technical instructions. SRAM says the drivetrain may make noise, Shimano flat out says the chain will probably rub on the big chainring. if you don't have any rubbing, you're one of the rare few.


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## Touch0Gray (May 29, 2003)

cxwrench said:


> it might not make noise, but the likelihood of it rubbing is high enough that both SRAM and Shimano make sure that it's spelled out clearly in their technical instructions. SRAM says the drivetrain may make noise, Shimano flat out says the chain will probably rub on the big chainring. if you don't have any rubbing, you're one of the rare few.


or their frames are out of alignment!


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## Hanna (Dec 14, 2011)

I have 39/50 105 5600 crank. I always had a very slight rub with a 105 chain. I just switched to a DA chain and now it's gone. You could try that.


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## cxwrench (Nov 9, 2004)

that's more likely because you have a 'new' chain rather than on old one now. there is no difference in width between 105 and D/A. the new chain will have less lateral movement due to no bushing wear.


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## DrSmile (Jul 22, 2006)

FYI I did take some measurements before I installed the spacers on the Campy compact crank. With Stronglight Zicral rings, the spacing between the rings is 0.7mm less, and this is entirely due to the large ring being set inward compared to the Campy ring.With the 0.6mm spacer the Stronglight rings are now still 0.1mm closer than with the Campy rings, but this seems to be functionally fine. I am not dropping the chain between the rings that's for sure. Back in the days when rings were flat this would have been a lot easier!


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## Hanna (Dec 14, 2011)

cxwrench said:


> that's more likely because you have a 'new' chain rather than on old one now. there is no difference in width between 105 and D/A. the new chain will have less lateral movement due to no bushing wear.


I'm not a pro mechanic but isn't a 105 5600 chain 6.1mm and a new DA chain 5.88mm?


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## cxwrench (Nov 9, 2004)

well, that's .22mm. i can see that making all the difference.


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## Hanna (Dec 14, 2011)

The bottom line is I have a quiet drivetrain in every combination. I was just passing along something that worked for me. You said there is no difference and you where wrong. Then you come back with sarcasm.


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## cxwrench (Nov 9, 2004)

Hanna said:


> The bottom line is I have a quiet drivetrain in every combination. I was just passing along something that worked for me. You said there is no difference and you where wrong. Then you come back with sarcasm.


let me edit my comment then...yes, you are correct there is a .22mm difference in the width of those 2 chains. there is no way that that will make a difference in the chain rubbing the chainring or not. especially when the bike is on the road...too much vibration and movement going on for that small of a difference in width to matter.


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## Hanna (Dec 14, 2011)

I have a lot of respect for anyone no matter how insignificant it may seem to admit when they are wrong. Thank you for that. The rest is simply your theory or an educated guess. You should also know the 105 chain rubbed when it was brand new. I am the one who actually demonstrated in the "real world" that it worked. I'm well aware of the small difference between the thickness of the two chains. I'm just saying it worked for me and it may help someone else.


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## Wazgilbert (Nov 7, 2012)

I have just used this thread to (partially) resolve my problem with rubbing on stronglight rings on campy compact. I found that with the campy set-up of 50/34, I could use all of the 10sp combinations to the 12-25 cassette. With the stronglight rings i chose - 52/36, I had the last 3 sprockets causing small "ting ting" noises on the 3rd, rubbing on the 2nd and clashing on the last.
I bought some 0.6mm spacers - fitted them tonight, and now have moved the issue down to the last sprocket only, and this is a mild rubbing, nothing on the 2nd.
So if someone made a 0.8mm I'm sure it would be silent across the board.
Thanks for helping me to find out I'm not the only one with this to solve!
(note- as being an UT set-up I have swapped between std and compact many times and all the combos were usable until I wanted to have a middle-ground, using affordable rings, rather than buying a whole chain set for Campy's 52/36)


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## Touch0Gray (May 29, 2003)

two .4 equals .8


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## robt57 (Jul 23, 2011)

Try a 10 speed chain, and no master link, rather shimano/pin.
Maybe even an 11 speed chain? I am using 10 speed chain on a few 9 speed setups currently.

Although the 9S jockey pullys and 11 speed chain may balk.


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