Difference between Shimano road and MTB derailleurs (was: FD for close ratios)

[Craig]

Thanks for useful replies (extract below). As a general question,
what are the fundamental differences if any between Shimano's MTB
derailleurs, e.g. Deore, and their road gear, e.g. Sora, Ultegra? I
suppose weight, but what about geometry or other factors?


Russel Seaton wrote:
I just set up my half step plus granny touring bike with a Shimano
Sora double front derailleur. Chainrings of 45-42-20. Shifts OK.
Cost was about $11.50 for the derailleur from Nashbar. Surprisingly
the derailleur is able to handle the 25 tooth difference on the front
without the chain dragging on the bottom of the cage when in the small
cogs in back.


[email protected] (Craig) wrote in message news:<[email protected]>...
> My old bike had an Exage FD with triple chainrings 28, 34, 40 (it's
> very flat where I live).

 

[Jeff Wills]

[email protected] (Craig) wrote in message news:<[email protected]>...
> Thanks for useful replies (extract below). As a general question,
> what are the fundamental differences if any between Shimano's MTB
> derailleurs, e.g. Deore, and their road gear, e.g. Sora, Ultegra? I
> suppose weight, but what about geometry or other factors?
>

A good place to start:
http://www.sheldonbrown.com/harris/derailers-front.html
http://www.sheldonbrown.com/harris/derailers-rear.html

I've had no problem comingling Shimano "road" and "mountain"
derailleurs, within the limits that Sheldon explains.

Jeff