Hi,
I have a 18 speed Scott Road bike. I need a new Front Derailleur? My last one is all rusty. How do I select a new one. I am bidding on a Shimano XTR FD-M971? Will this work? How do you know which one will work? Will almost Front Derailleur work?
Thanks
Tim
Five things to note:-
1) Road bike or MTB
2) Triple or double.
3) Diameter of down tube or if "braze on" mounted.
4) Diameter of chainrings.
5) Top pull or Bottom pull.
You say road bike?
If you have road shifters (STI) then an MTB mech' (XT) won't work.
Road / MTB mech's have different pull.
Triple or double - self explanatory!
Down tubes have different diameters so need to note "band on " diameter.
(Some new mech's come with adapter rings. If "braze on" fitting then have to be braze on type.)
Large chainrings require a different front mech' than small ones. The curve of the "cage" is different.
Top / Bottom pull means the direction the cable takes to connect to the mech'.
MTB's tend to be top pull and road bikes usually bottom pull (but not always)
(Again some mech's have an adaption to work with either.)
Ride hard or ride home alone!
Hi,
I have a road bike.
I have three large sprockets
You can attach it on the frame of the bike.
I have no idea of the size of the chainrings- How do I figure this out?
Bottom Pull.
So when I look for a derailleur, how do I know if it is for a road bike and will it fit my bike?
Thanks for taking the time to answer.
Tim
The easiest and safest way is to buy and fit the same one.
Stick to the same manufacturer if possible. So if Shimano then get a Shimano.
Shimano have a "Road" range and an "MTB" range and if you look at any decent shops website they are usually listed under "road" or "MTB" headings.
Campagnolo only do "road" gears now as they dropped their offroad stuff.
If you are buying through the internet then check the description.
Check the "speed" rating (8/9/10 speed) but quite often there is no problem if you chose a 9 instead of an 8 speed.
If your buying from your LBS then ask their advice.
Edit: I see Joe has posted while I was writing, glad we are saying the same thing ?!?.
The size of the rings is just the number of teeth. So with your road bike I would guess your largest ring is around 50/52 teeth?
So the chances are you can use any of the Shimano "road gear" range within your speed rating.
If your chainset is say 46/36/26 then you might have to be more carefull with your choice.
Ride hard or ride home alone!
Loads of info here,http://cycle.shimano-eu.com/