I'm building up an old Peugeot frame with a modern 10 speed Hollowtech II setup. The rear spacing was reset to 130mm from 126mm when it got resprayed. Every seemd ok until I started setting the gears up, somethings not quite right with the chainline. At least I'm assuming its the chainline. On the big chainring and smallest sprocket the chain is rubbing against the next spocket but only on the top of the cassette. On the bottom the rear mech holds it in the right place and the dropout, hub, cassette and rear mech look perfectly in line. Chain is definitely a 10spd so its not a chain width issue and obviously this issue will be worse on small chainring. Is there supposed to be a spacer between the BB cup and the bb shell that I've missed?
What have I done wrong - modern Hollowtech II question
- Thread starter Kerplunk
- Start date
Hi Kerplunk 
I've had this issue on my Paganini for quite some time but ignored it until I read Spibbo's post re: the same issue. Spibbs figures his mech hangar is bent / misaligned and I agree.
I'll mention to you what I told him, " If the rear stays are reset from 126 > 130 then the hangar will kick out. A 4mm reset of the stays also alters the hangar line by a factor 4mm. If a reset from 130 > 126 then the hangar will kick in. Do you see what I mean ?
I also read somewhere in here recently that someone was having issues with the smallest sprocket constantly trying to jump up 1 because of the way the new style sprocket teeth are designed, as in self changing. Add this info to your re-spacing and you'll be very near to whatever it is thats actually causing it.
In Spibbs case, he used his LBS for the job, but thats no guarantee the lad who did it knew his stuff. I suspect that the real old guys in here will know what the problem is, especially the old frame builders. Sadly I don't know them yet .... but there's always time
I always knew of this kind of issue to be known as " accumulated error". 4mm on the stays = 1.3mm on the hangar = 0.8mm offset in the chain alignment at its worst ie: large ring / smallest cog. These figures are not accurate / real, just an example of how small details can make for a crap running mech in certain gears.
As a final thought, " I am finding that old frames haven't got the clearance on the rear stay for the 130 set wheels even when re-spaced because the angles are wrong / not designed to accomodate 10speed systems. They where designed for 6-7 speed. Its not just the spacing, but the shape of the rears. I have had 2 sets of 10spd 130 wheels touch the actual stay on the last cog, yet 9 speed miss ? BOTH 130 set wheels, yet more clearance because 1 set has 1 cog less. The wheels fitted fine, but the chainline couldn't clear the extra difference between 9 & 10.
Hope this helps some. Later Kerplunk, Laz.
I've had this issue on my Paganini for quite some time but ignored it until I read Spibbo's post re: the same issue. Spibbs figures his mech hangar is bent / misaligned and I agree.I'll mention to you what I told him, " If the rear stays are reset from 126 > 130 then the hangar will kick out. A 4mm reset of the stays also alters the hangar line by a factor 4mm. If a reset from 130 > 126 then the hangar will kick in. Do you see what I mean ?
I also read somewhere in here recently that someone was having issues with the smallest sprocket constantly trying to jump up 1 because of the way the new style sprocket teeth are designed, as in self changing. Add this info to your re-spacing and you'll be very near to whatever it is thats actually causing it.
In Spibbs case, he used his LBS for the job, but thats no guarantee the lad who did it knew his stuff. I suspect that the real old guys in here will know what the problem is, especially the old frame builders. Sadly I don't know them yet .... but there's always time
I always knew of this kind of issue to be known as " accumulated error". 4mm on the stays = 1.3mm on the hangar = 0.8mm offset in the chain alignment at its worst ie: large ring / smallest cog. These figures are not accurate / real, just an example of how small details can make for a crap running mech in certain gears.
As a final thought, " I am finding that old frames haven't got the clearance on the rear stay for the 130 set wheels even when re-spaced because the angles are wrong / not designed to accomodate 10speed systems. They where designed for 6-7 speed. Its not just the spacing, but the shape of the rears. I have had 2 sets of 10spd 130 wheels touch the actual stay on the last cog, yet 9 speed miss ? BOTH 130 set wheels, yet more clearance because 1 set has 1 cog less. The wheels fitted fine, but the chainline couldn't clear the extra difference between 9 & 10.
Hope this helps some. Later Kerplunk, Laz.
Cheers for the reply. Re-spacing was done at Bob Jackoson when they had the frame for a respray so it should have been done properly. Certainly to the naked eye it looks like dropout, mech and cassette are in line and parallel. There's no rubbing on the next sprocket at the bottom of the cassette so no catching and trying to jump a gear. If it was a dropout alignment issue I'd have thought (probably wrongly) I'd see a problem there.
As the rubbing is only as its leaving the cassette at the top I was thinking (again probably wrongly) that the major factor on the chain direction at that point is coming from the chainring thats pulling it round. Its not catching the sprocket by much so spacing the BB cup out a couple of mm will probably solve it. Just wondered if any else had had the same thing and managed to sort it out. I can't remember seeing a spacer in the BB box but its possible there was one and I've just not fitted something I was supposed to...
As the rubbing is only as its leaving the cassette at the top I was thinking (again probably wrongly) that the major factor on the chain direction at that point is coming from the chainring thats pulling it round. Its not catching the sprocket by much so spacing the BB cup out a couple of mm will probably solve it. Just wondered if any else had had the same thing and managed to sort it out. I can't remember seeing a spacer in the BB box but its possible there was one and I've just not fitted something I was supposed to...
chainline
here is an article which explains chainline in detail
http://www.sheldonbrown.com/chainline.html
zybernut
here is an article which explains chainline in detail
http://www.sheldonbrown.com/chainline.html
zybernut
Had a chat with LBS mechanic yesterday and although he said officially they don't recommend doing it for road bikes but they do it for MTBs. He very helpfully gave me a plastic spacer to try if I wanted to so will venture out into the garage tonight to see if it works.
Nice to know you have it sorted Kerplunk My only other thought would have been BB axle length. Again I'm having small issues with axle lengths that fitted 1 frame but won't transfer directly to another frame. Since I only re-build 70's-90's bikes with likewise kit I'd always assumed that BB shells where the same, but I'm now realising that some frames are 68mm and others 70mm. To my eye, the same, but to the chainset when fitted, 2mm too close to the bike, and a rear mech running like a naughty boy.
Later my friend, Laz.
My only other thought would have been BB axle length. Again I'm having small issues with axle lengths that fitted 1 frame but won't transfer directly to another frame. Since I only re-build 70's-90's bikes with likewise kit I'd always assumed that BB shells where the same, but I'm now realising that some frames are 68mm and others 70mm. To my eye, the same, but to the chainset when fitted, 2mm too close to the bike, and a rear mech running like a naughty boy.Later my friend, Laz.
