Chain rub?

Stephenjames

Hi,

Could anyone please help me? I am having trouble eradicate 'chain rub' from my Dura Ace 10 speed (mechanical) drive train on my Litespeed Tuscany. It would seem that no matter how finely I tune front derailleur there is always 'rubbing' either on the inside or outside of the cage. Could anyone give me a heads up??

Thanks Steve.

StillGoing

What everywhere? Which combinations of gearing give you chain rub.

trailflow

Are you using the trim function ?

mallorcajeff

Bet the rear hanger is slightly out of alignment. No matter how much you fiddle it wont ever be right if the hangers bent. You dont need to crash or bang it to bend it. My time trial bike used to always do it and was forever straightening it as it would just flex under full efforts and bend. Turns out it was made of cheese, bought another one and never had the same issue. If you dont have the tool run it to your lbs and ask em to check it (30 second job)

mallorcajeff

Ignore that, missed the bit where it said front deraileur haha

Anonymous

I had an old Tiagra front mech that did a similar thing. When I took the chain off and tried to fine tune it, I noticed that the chain ring wasn't moving right. I could see it wobbling from left to right ever so slightly. I had to replace the whole front chain ring set to fix the problem.

Not saying you have the same problem but its something to consider.

rafletcher

Stephenjames wrote:

Hi,

Could anyone please help me? I am having trouble eradicate 'chain rub' from my Dura Ace 10 speed (mechanical) drive train on my Litespeed Tuscany. It would seem that no matter how finely I tune front derailleur there is always 'rubbing' either on the inside or outside of the cage. Could anyone give me a heads up??

Thanks Steve.

Chain rub in what combination? Big - big - yep, you'll get it. Small - small - yes again. Because those are combinations that are "extreme" and not regularly used. Though it seems only old folk like me believe in mechanical sympathy, and others think all gears should be available with no issues. So get SRAM where the front mechs "yaw" to get round this issue.

Bozman

With Dura-ace you don't get trim but if it's set up correctly you don't tend to get much rub even on big big. On the old 7800 I had no rub at all on one set up, you could drop that chain in the forbidden zone(53/25) and you just get a bit of chain noise due to the alignment.

trailflow

My Dura Ace 7900 has a trim on the small front ring. I can run small/small without any chain rub.

Bozman

trailflow wrote:

My Dura Ace 7900 has a trim on the small front ring. I can run small/small without any chain rub.

There isn't any trim on 7900.

trailflow

Yes there is. They must have revised the left shifter at some point. I'll make a video to show you.

This thread confirms it aswell.
http://weightweenies.starbike.com/forum ... =3&t=88674

Stephenjames

Thanks for all your kind replies. Basically there is chain rub on the outer and inner front derailleur cage in gears 1 and 10. When using top gear there is no chain rub at all. I live in hilly Devon and use a lot of the small gears so it would be really useful if I could eliminate the chain rub. When using the small chain ring there is chain rub on either extreme of the cassette. I have been told it is possible to get rid of the chain rub, just takes a bit of skill and fore-thought. If anyone can help me I would be most grateful. Thanks.

rafletcher

Stephenjames wrote:

Thanks for all your kind replies. Basically there is chain rub on the outer and inner front derailleur cage in gears 1 and 10. When using top gear there is no chain rub at all. I live in hilly Devon and use a lot of the small gears so it would be really useful if I could eliminate the chain rub. When using the small chain ring there is chain rub on either extreme of the cassette. I have been told it is possible to get rid of the chain rub, just takes a bit of skill and fore-thought. If anyone can help me I would be most grateful. Thanks.

I'd expect there to be rub small/small, but not small/big under usual circumstances. Maybe you should learn to change to the big ring when halfway down the cassette to avoid small/small?

trailflow

Stephenjames, Are you using 7800 or 7900 Dura Ace ?

It sound like the low limit screw isn't set correctly. Put the chain on the small front ring and lowest gear (biggest cog) at the back. Then try slowly turning the low limit screw outwards. You should see the front cage move to the left. Leave a gap of around 0.5/1mm from the chain and inner cage

For the other end of the cassette, you may a have trim function on your left shifter. Basically you can nudge the front derailleur to the right slightly if you do a gentle sweep of the left shift lever. You will feel and hear a smaller click before the big shift up onto the big ring. You may have to play around with the cable tension. If you have a barrel adjuster installed then use it.

Plenty of tutorials around the web on how to properly set up a front derailleur and lots of videos to guide you on youtube.

Stephenjames

Hiya trailflow,

Thanks for the heads up. I am using Dura Ace 7900. I don't think there is any 'trim' to speak of. I will check out the youtube vidoes and see if I can get my head around it. Thanks once again for advice.

Mad_Malx

If you have a band-on front derailleur you might want to check that the derailleur is aligned in parallel with the chainrings.

JayKosta

It might be that the sides of the cage are bent slightly inwards.
Is the gap at the opening the same as at the top?

Jay Kosta
Endwell NY USA