Stupid FD Clamp Question

[tuxbailey]

I have always been curious about this but never found the answer. Since my teacher always said that there were no stupid questions...

I have a Chorus FD. It is mounted to a Shimano clamp. So is the FD a Brazed on or Clamp on?

OTOH, how do I find out the size of the clamp if I want to jump on any nice deals on the classified section.... This is for the 2005 Merlin Extralight

[Skenry]

You have a braze-on deraileur.

As for the clamp size, someone here will know off the top of their heads, but why not just measure to diameter of the seat tube? I'd guess a 28.6mm.

Scott

[vqdriver]

der is a braze on.

clamp size is on there somewhere. if not visible on the outside, then probably stamped on the inside of the clamp. this may or may not also be the same size as your seatpost clamp size.

[tuxbailey]

Thanks. I guess it will be 28.6mm since the seatpost is 27.2.

[Louis]

I have a Chorus FD. It is mounted to a Shimano clamp. So is the FD a Brazed on or Clamp on?

The FD is called a "braze on" FD because it's designed to be bolted to a brazed-on bracket. However, since some (most?) frames do not have a brazed-on bracket, component manufacturers also make clamp-bands that duplicate the geometry of the braze-on at the FD interface, allowing you to use the braze-on FD on a non-braze-on DT.

Non-braze-on frames that don't have funky DT cross-sections are more versatile, because you have more flexibility in locating the FD, allowing you to match a wider range of chainring combinations. With the braze-on you're limited by the height of the slot.

[bikinchris]

The Shimano braze on adapter has the size on th einside of the band. There are only three sizes. 28.6 (which is no longer available), 31.8 and 34.9mm. If you have a 28.6mm tube and want to use a Shimano clamp you will require a spacer. The seatpost size has NOTHING to do with the diameter of the front derailleur clamp.

[oldpotatoe]

The Shimano braze on adapter has the size on th einside of the band. There are only three sizes. 28.6 (which is no longer available), 31.8 and 34.9mm. If you have a 28.6mm tube and want to use a Shimano clamp you will require a spacer. The seatpost size has NOTHING to do with the diameter of the front derailleur clamp.

BUT there are many 28.6 clamps made, like the Problem Solver one...

[AngryScientist]

i have a lot of opinions:)

it is my opinion that all men who do at least ANY work mechanical in nature (like work on bikes) should own a nice measuring caliper. pretty basic ones can be had for relatively cheap money and they take the guess work out of little things like this. i've had one since college, and really use it more often than i would have ever thought.

tis the season, treat yourself:)

http://www.hornady.com/store/images/P/050075-Steel-Dial-Caliper-New.jpg

[vqdriver]

i really use it more often than i would have ever thought.



i agree

[Don49]

Thanks. I guess it will be 28.6mm since the seatpost is 27.2.I assumed that on a Serotta and was wrong. You really want to double check.

[DHallerman]

I have always been curious about this but never found the answer. Since my teacher always said that there were no stupid questions...

I have a Chorus FD. It is mounted to a Shimano clamp. So is the FD a Brazed on or Clamp on?

OTOH, how do I find out the size of the clamp if I want to jump on any nice deals on the classified section.... This is for the 2005 Merlin Extralight

I have a mid-1990s Merlin Extralight, and the front derailleur clamp is 35.0mm (aka, 34.9mm).

There is no real relationship between seatpost diameter and front derailleur clamp diameter.

[tuxbailey]

I have a mid-1990s Merlin Extralight, and the front derailleur clamp is 35.0mm (aka, 34.9mm).

There is no real relationship between seatpost diameter and front derailleur clamp diameter.

Ok...

I don't have AS' nice caliper (which I will definitely get) I took a piece of wire and measure the approximate circumference of the clamp area and it is about 110-115mm. That yields the OD to be about 35mm.

So I guess 34.9mm is the winner here.

[AngryScientist]

So I guess 34.9mm is the winner here.

that's what my Merlin uses, though its not an XL