Oxygen_H

Hi All.
Can anybody help me? I planned setup on my touring Shimano STI shifters. Bu I have mountain groups Chainrings (Deore). I know, that didn't comatible with each other. Is anyone solver this problem?
Yours trully, Viacheslav Besedin.
RUSSIA.
PS: sorry for my bad English.

Al1943

I have never tried this and could be wrong. Perhaps someone else can give you more help.
You may be able to use a "down pull" mountain type derailleur. The cable will need to pass under the bottom bracket. There will need to be a cable guide under the bottom bracket. Indexing will not be the same as mountain style shifters. Road bike triple STI shifters have 4 positions for the 3 chainrings. Mountain bike shifters and derailliers do not have the same spacing and throw ratios as road bikes.
I believe you may be able to make it work anyway.
Good luck, let us know how it turns out.

Al

Steev

You won't have any problems with the chainrings themselves, the incompatibility is with front deraillers. They are cheap, maybe just get a road series front derailler, 105 would be a good choice and it should all work fine.

bluehair

I'm not sure of your question. Do you already have mountain chainrings on a road bike or are you trying to put road drop bars on a mountain bike? If you have a road bike that already has a working mountain bike triple crankset on it, the front derailleur you have is fine. Shimano STI road shifters will work. If you are trying to put a mountain crankset on a road bike with STI shifters, you can do that, but you will need the correct front derailleur. The FD cage is shorter and wider for a mountain crankset than for a road crankset. I currently use an XTR crankset, an XT front derailleur and Ultegra shifters (9 speed) on my touring bike; it's a nice setup for hilly terrain. Your rear derailleur needs to be able to handle the new difference in total teeth if you only had a double crankset there to begin with. Good luck.

cs1

As mentioned before, any road STI compatible ft derailleur will work. The MTB front derailleur has a slightly different pull length and isn't compatible with the STI shifter. Good luck

Tim

Oxygen_H

Many thanks to all answered. Probably, the best decision use of the road derailleur will be valid. However seat tube diameter on my bicycle 31.8 I do not know diameter, whether there are road switches with such clamp diameter? Here still the interesting information which to me managed to be found: https://www.ctc.org.uk/DesktopDefault.aspx?TabID=%204068
Very yhanks, Viacheslav/

Michel Gagnon

Yes there are. That's probably close to the diametre of the seat tube of our tandem and I had no problem finding a road derailleur. That should be the case in Canada, U.S. and Western Europe at least.

If you have bottom pull, no problem in finding a road derailleur; with top pull (i.e. cable coming from the top), I have no idea.

As for compatibility, once you have a road derailleur, you should not have any shifting issues. One potential problem is the chain falling down "inside" the small chainring. If that's a problem, I would suggest installing a gizmo such as the n-gear Jump Stop.

Oxygen_H

Men, i resolve upon front road derailleur. But how about chainline? At my rear cassete and front mountain crancs and bottom bracket chainline is 47.5 . But road front derailleur has chainline 45. Is it a big problem?
Sincerelly yours, Viacheslav Besedin aka Oxygen_H

cs1

Our never ending quest continues. I'm sure someone here has attempted what you are trying to do. I have an old set of 7 speed RSX brifters that I want to mate to an old Deore 7 speed group myself. I am waiting to see the result.

Tim

HillRider

I did the conversion to drop bars with STI shifters on a '93 Trek 7000 rigid fork, hardtail MTB. The routing of the front derailleur cable didn't make substituting a road fd easy and the STI wouldn't index properly with the Deore LX fd. I wound up using a barcon shifter for the front.

cyccommute 

It shouldn't be. If you want you can always go with a shorter bottom bracket to move the chainline inward. Going from a 118mm bottom bracket to a 113 mm bottom bracket will bring you in the required amount. Read what Sheldon Brown has to say about chainlines first, however.