Seat Stay Diameter Question

[cubalz]

Hello all! I have a 1999 F500 that I want to upgrade the front derailleur but I have no idea the diameter of the seat stay in order to get the correct clamp on size. The frame is a size large.

Any help would be appreciated!

Thanks!
John

 

[black lightning 1987]

I think you mean seat tube diameter. It will take a 31.8 mm clamp (some manufactures label them 32 mm). Be sure to get a derailleur that is compatible with your shifter. Generally speaking, same brand and same era - probably 9 speed in 1999.

 

[cubalz]

Yes that is what I meant. Thanks black lightning!

 

[cubalz]

Oh geez, I have decided to go with a bottom pull Shimano XT front derailleur but I am overwhelmed to say the least. I found a bunch of likely candidates on eBay but there are a ton of vintage 31.8mm triple chainring front derailleurs in scores of different model numbers: FD-M735 and FD-M737 (both Shimano XT 3 x 8 bottom pull) How would I know what one would be correct one? Is it possible to assume that any of those would work since they all feature the correct clamp and chainring number? I am beyond confused....

I have confirmed that it has a 3 x 8 drivetrain.

 

[black lightning 1987]

If you have rapidfire shifters I would stick with the same era XT front derailleur, that is: 8 speed. The newer 9 speed models may have been made for a different pull ratio. I think you would be safe with either M735 or M737 front derailleurs.

 

[cubalz]

Perfect, thank you so much for your help!!!!