Component help needed..

JakeJ

So I'm currently pricing up some components for a frame that I'm planning on building up for when the warmth returns, I won't say summer because this is England..

Now I thought most things were pretty straight forward, however this doesn't seem to be the case..

My first question is about front Derailleur's..

Now I keep seeing the term 'braze on' or 'band on' ect.. but I've not seen a braze off ect.. So are they all braze on?

Not that I know what braze on actually means, if anyone could shed some light?

Now the next part also about front Derailleur's..
I was just about to add one the my basket and I see that there's two options for sizes.
I had no idea that they also came in different sizes, nor that it mattered if you're running 10 speed or 11 speed.

I'll be changing to 11 speed anyway so that part isn't important, not that I can see what difference it makes on the front.

Anyway, so my two options are.. 28.6/31.8.mm & 34.9mm I have no idea what these measurements are referring to.

But If I say that I'm looking to use the Ultegra R8000 crankset in a 52/36, does that affect which size Derailleur I have to use?


Bicycles, who'd have thought they'd be so complicated?

Thanks.
Jake.

i.bhamra

A braze-on derailleur mounts directly to the frame via a fitting point welded to the frame.

http://www.wiggle.co.uk/shimano-105-5800-braze-on-front-derailleur/

A band-on mech has an attached circular clamp so it can be fitted to a frame that does not have the mounting point welded to the frame.

http://www.wiggle.co.uk/shimano-ultegra-6700-band-on-front-derailleur/

The different sizes you are seeing refer to the band-on derailleurs and in particular the external diameter of your down-tube where you would attach the derailleur.

Braze-on derailleurs can be converted to fit frames suitable for band-on by way of an adapter.

https://www.evanscycles.com/shimano-6700-ultegra-di2-front-derailleur-band-adapter-28-6-31-8mm-EV152950

The main difference between 11 speed and 10 speed will be the width of the cage (either could be made to work work but would recommend getting the correct one for your chain).

Depending on the size of largest chain ring you simply move the derailleur up or down the mounting point on the down tube so the cage clears the chainring by a coupl of mm.

dj58

i.bhamra wrote:

A braze-on derailleur mounts directly to the frame via a fitting point welded to the frame.

http://www.wiggle.co.uk/shimano-105-5800-braze-on-front-derailleur/

A band-on mech has an attached circular clamp so it can be fitted to a frame that does not have the mounting point welded to the frame.

http://www.wiggle.co.uk/shimano-ultegra-6700-band-on-front-derailleur/

The different sizes you are seeing refer to the band-on derailleurs and in particular the external diameter of your down-tube where you would attach the derailleur.

Braze-on derailleurs can be converted to fit frames suitable for band-on by way of an adapter.

https://www.evanscycles.com/shimano-6700-ultegra-di2-front-derailleur-band-adapter-28-6-31-8mm-EV152950

The main difference between 11 speed and 10 speed will be the width of the cage (either could be made to work work but would recommend getting the correct one for your chain).

Depending on the size of largest chain ring you simply move the derailleur up or down the mounting point on the down tube so the cage clears the chainring by a coupl of mm.

Just to clarify, when you refer to the FD mounting point on the down tube, you really mean the seat tube. The down tube is the diagonal tube located between the head tube and the BB. I'm sure you are aware of that and have just mixed up the terminology.

cycleclinic

buy a braze on FD and a braze on adapter then you have a FD that can be swapped to a different bike. there should only be braze on FD's.

keef66

I bought a carbon frameset with a braze on mount for the FD. I wanted to transfer the groupset from my alloy bike which appeared to have a band-on mech, so I bought a new braze-on front mech.

Then when I stripped the alloy bike I discovered that it actually had a braze-on FD with a band-on adapter :roll:

(The new one was shinier so I kept it anyway. And you never know when a spare front mech might come in handy. Been in the drawer for nearly 5 years so far....)

i.bhamra

DJ58 wrote:

Just to clarify, when you refer to the FD mounting point on the down tube, you really mean the seat tube. The down tube is the diagonal tube located between the head tube and the BB. I'm sure you are aware of that and have just mixed up the terminology.

Thanks! Silly mistake. Hope the OP doesn't try mounting a mech to his downtube....