Bicycle Mechanics - front derailleur clamp size?

Question: I am replacing the front deraileur on my 2002 Giant Iguana frame with a Shimano LX drlr. I am unsure of the clamp size as it comes in 3 different ones: 28.6 mm, 31.8 mm, and 34.9 mm. I have a 31 mm seatpost, and thats all the info i have. there is no info from the giant homepage, and my lbs (over the phone) didnt know, but guessed 31.8. i think it would be 34.9 with that size seatpost though yes? anyone with any info i'd appreciate it!

At another forum I frequent there is a member that works at Giant. I'll contact him and ask for you. Give me a little while to hear back from him.

In the meantime, rule out the 28.6 that's generally used on older thin diameter steel frames.

You could also just measure the thing if you've got a venier caliper. If not, wait a little and I'll try to find out!

L8R

Duh,

Take the existing one off your bike. The size should be stamped on the inside of the clamp!:rolleyes:

L8R

Originally posted by a2psyklnut
Duh,

Take the existing one off your bike. The size should be stamped on the inside of the clamp!:rolleyes:

L8R That works,as well as measuring the diamerer, or the circumference and doing the math.

Airborne,

Check out the Giant site. There is a link to see the Iguana's geometry as your looking at the general info for it. I believe it gives the diameter of the seat tube in millimeters. As long as this is the measurement at the front derrailleur clamp, you should be able to figure it out with this.

-Moab

Originally posted by moabrider47
Airborne,

Check out the Giant site. There is a link to see the Iguana's geometry as your looking at the general info for it. I believe it gives the diameter of the seat tube in millimeters. As long as this is the measurement at the front derrailleur clamp, you should be able to figure it out with this.

-Moab

thanks, but as i stated, nothing is on the site.

I haven't an Iguana, but my Giant has a 30.8 seatpost and uses the 34.9 clamp so probably...

Richard

This if from Sheldon Brown's site:

1 1/8" (28.6 mm) clamp on. (This is the traditional, standard type for most road bikes and older MTBs.
1 1/4" (31.8 mm) clamp on for mildly oversized seat tubes.
1 3/8" (34.9 mm) clamp on for oversized seat tubes, common on aluminum frames.

Just replaced mine on a Giant XTC NRS 2. It was 34.9.

thanks richard and dirt... that is very halpful and sounds on the money!:beer: