BHBiker

Anyone can tell me the difference between the two? A lot of the FD in eBay are braze on types,...why is that? what are the advantages over the other type? Is the other type a clamp-on type? thanks for the help guys!

Retro Grouch 

If your bike has a braze on for the front derailleur, that's what you have to get.

If your bike doesn't have one you can either buy a clamp on front derailleur or use a braze on front derailleur along with a separate clamp.

Clamp-ons generally give you a little more freedom to locate your front derailleur a little bit higher or lower. That can be useful if you decide to install a compact crankset onto a bike that was designed for a traditional crankset.

BHBiker

in that regard, are braze-on types reserved for those higher end models? or is it just a design variance? thanks again

capwater

Nothing to do with it. Many bikes with fatter seat tubes go with braze-ons with an adapter clamp. Every carbon bike I've encountered also uses a braze-on with an adapter bolted into the seattube.

HillRider

Carbon bikes usually come with bolt-on front derailleur tabs since the seat tubes aren't round so no clamp-on or clamp-on adapter will fit.

On steel, Al or Ti frames (with round seat tubes) you can buy clamp-on adapters in any of the three common diameters which allow you to use any braze-on style derailleur.

oilman_15106

If you have any intention of moving your components to another bike or upgrading in the future, go with a braze on der. and appropriate band clamp. Will be cheaper in the long run.

terry b

Lots of generalizations in these threads. I have 4 carbon bikes, 2 with braze-on and two without - so much for rules of thumb. There is acorrelation to tubing shape though - oddball tube shapes require braze-on and this is true regardless of farme material. Of course this doesn't explain the round tube metal bikes I have with braze-ons.

Aside from tubing shapes, builders use braze-on FDs for reasons known to them. There is no design advantage one way or another. If your bike has the tab - you need a braze-on. As has been said, if your bike does not have the tab you can either buy the derailleur with correct clamp for your seat tube or you can buy a braze-on and the correct band clamp. Either way works just fine.

BHBiker

Thanks a lot. The reason I am asking is that a mate of mine mentioned that braze-ons are common to higher end carbon bikes which I found to be a weird generalisation. Thnaks again

BHBiker

its good to have this forum around. Its separates fact from fiction, at least for a semi-newbie like me it does.

HillRider

It's still a "rule of thumb", it just isn't universally true. Carbon frames made with round carbon tubes and either lugs or bonded joints can use a clamp-on fd since the seat tube is (wait for it...) round. However, most molded and a lot of bonded carbon frames have flaired, aero or other shaped seat tubes and must have a "braze-on" tab. And, it isn't universally true that metal frames have round seat tubes either so some of them have braze-on tabs out of necessity.

Older high-line steel frame bikes, even though they had round seat tubes, often came with braze-on (in this case it really was brazed on) fd tabs because braze-on fittings in general were the sign of a superior frame and the more the better. Also there was a minute weight savings with a braze-on fd.

BHBiker

so far my learnings on FD 101: clamp ons are used more often than not on round seat tubes but is not always the case. braze ons are also used but not as much as clamp ons unless they want to save a few milligrams.

braze ons are used on non circular/round tubes for aero type seat tubes for obvious reasons. With the advent of aero designs such as the P3 etc etc ,..there is a need to have braze on type FDs. Its alos good for saving a bit of weight (no matter how small.

Bothbraze on and clamp on are equally useful and there is not much differential advantage amongst the two except for some weight savings. DID I understand it right?

Blue Jays

Hi All-

To further throw additional confusion in the mix, very high-quality custom titanium models such as those offered by Tom Kellogg / Spectrum / Merlin are built with seat tubes designed specifically for clamp-on front derailleurs. Apparently this is done to ensure maximum strength in the bottom bracket area.

~ Blue Jays ~

HillRider

Right, and Litespeed, which used to have braze-on fd tabs on it's higher line Ti frames, dropped them a few years ago and uses clamp-on fd's on everything except it's TT/Tri frame.

terry b

I think custom builders design and build for clamp-on because it's a pain in the neck to braze on a tab which offers absolutely no benefit to the owner of the frame. Why bother doing the extra welding when there are a million clamp-on options?

At the same time most custom builders offer braze-ons such as a derailleur tab at an upcharge. I suspect that reflects the cost of the extra work in materials and time. I've had this very discussion with 4 different builders who have done bikes for me and the answer is always "why bother?"

There is no appreciable weight saving since you're trading a steel FD tab for an aluminum clamp. Performance-wise - no difference.

Barabaika

Advantages of braze-on front derailleurs:
* don't squeeze thin-wall seat tubes. High-end butted steel tubes can be very thin, and plastic tubes flex.
* look better
* don't leave marks on the paint when are moved. For example, you go from a standard crankset to a compact; ugly.
* less components

HillRider

OK but brazing or welding the tab causes a heat-affected zone right where the tube is the weakest. One of the reasons butted tubes are thicker at the ends is to have enough strength after the brazing or welding heat has done it's damage.

vpiuva

Stick around a little longer

Barabaika

There are many other braze-ons on a frame. One more, one less.
Frame builders usually use low-temperature silver brazing for braze-ons.
The better a frame builder, the quicker and safer he will braze.

Though, putting a braze-on depends more on a frame builder's preference like holes in the top tube for the brake cable.