Front mech.

[KM2]

I’m wanting a front mechanism where the clamp is at the bottom of the mechanism, or a clamp for a brazed on mechanism where the clamp is at the bottom. Does that type exist, has to be for a compact or 53 big ring, so no mountain bike mechs, I guess. Can be flat plate old style, that doesn’t matter.

[gaz]

Shimano RSX.

No knowledge of seller or item, just a vague memory of RSX (mid 90s), seems to fit your description.

[Brucey]

'top swing' mechs (ie. with a low band and an elevated cage) are commonplace in the world of MTBs but not so much outside of this, I would expect careful analysis to show if there is anything else to worry about. I think you will be lucky to find any top-swing FD that is designed for chairings over 48t or so.

ps. I wonder if you could make the mech of your dreams by (say) welding a cage from one mech (which will handle 53t) to the workings of another (eg. an RSX)? A 'Frankenmech' of this sort might be the only way of getting what you really want.

[KM2]

Thanks with your description, something like this might do
Shimano FD-TX800 Tourney TX Front Derailleur, Top Swing, Dual Pull

Seems to do a 48t.
Just need to match tube diameter

[gregoryoftours]

That Tourney mech is not designed for road chainline and cable pull if that's what your setup is, it might work fine if you're lucky or might need a bit of futzing about to get it to work as well as possible, including possibly buying one with an oversized clamp and using/making an asymmetric shim, and altering the cable pull with cable clamp alteration. Also 48 is quite a bit away from 53.

[gregoryoftours]

Shimano RSX.

No knowledge of seller or item, just a vague memory of RSX (mid 90s), seems to fit your description.

This looks like the best bet to me if clamp size is compatible as it is an actual road mech. Will hopefully work chainline/cable pull wise and also accommodate larger road size chainrings.

[Brucey]

Shimano RSX.

No knowledge of seller or item, just a vague memory of RSX (mid 90s), seems to fit your description.

This looks like the best bet to me if clamp size is compatible as it is an actual road mech. Will hopefully work chainline/cable pull wise and also accommodate larger road size chainrings.

this may all fall down because RSX may have run a very MTB-eque chainline and from memory the big ring on an RSX triple is 46t.

[KM2]

I did put compact or 53 ring. Done my calculations and 53 minimum big ring.
So 53/39 would be the minimum.(small wheels)
Thanks for your help. I think I can sort it from here.
Trying to remove a 3*7/8 hub system.
Would need an 11/12/13/14/15 then increase jumps.

[gaz]

this may all fall down because RSX may have run a very MTB-eque chainline and from memory the big ring on an RSX triple is 46t.

Tech doc for FD-A410 which I think gives the chainline as 37-51mm. It does not give info on chainring sizes but if's pictured with a 36-46 double and the curve of the cage suggests it can handle something larger. Of course the pic could be illustrative rather than to scale and A410 is not A416.

[peetee]

I’m wondering why you need this combination.
Is it because a bottle cage mount is in the way, perhaps?
It could be that a brazed-on style mech and separate mount will get you away from a bottle cage boss.

[KM2]

The bike structure is not compatible with any other type of mech. It could bridge the structure and bolt on. But is it too much work.???

I’m just piddling about trying to remove the drag of a hub gear.

[tatanab]

Similar circumstance. A conventional front mech shoehorned in place. Cable is routed through the noodle, under the bottom bracket and back up to the mech. A clubmate with the same frame has used a top swing mech with the same cable routing. Both work fine. My mech is very close to the fat main tube, but if there was insufficient room I could have fitted a smaller ring than the current 52.

[Brucey]

surely you just need a better hub gear?

FWIW if you do decide to fit a FD, I suggest fitting a BO mount to the frame. It looks like you could do with some extra braze-ons anyway, so you could perhaps get it all done at the same time.

[Brucey]

100_1563.JPG
Similar circumstance. A conventional front mech shoehorned in place. Cable is routed through the noodle, under the bottom bracket and back up to the mech. A clubmate with the same frame has used a top swing mech with the same cable routing. Both work fine. My mech is very close to the fat main tube, but if there was insufficient room I could have fitted a smaller ring than the current 52.

can you be done for 'cruelty to cable hangers'? That is undoubtedly ingenious, but had I wanted to do something similar, I would probably have welded or brazed something directly to the 'v' pipe/noodle tube. Being steel, this ought not be too difficult to do.

[slowster]

I suggest you do some measurements, e.g. how high would the derailleur need to be for your proposed outer chainring size. For each extra tooth the chainring radius increases by ~2mm.

You might be able to achieve what you are seeking by fitting a front derailleur clamp adapter for braze on mechs, and mounting a front derailleur dropper upside down. There are a few such products, and I expect they vary a bit in how much lower (or higher) they could position a braze on front derailleur.

https://www.spacycles.co.uk/m8b0s106p26 ... Mech-Clamp

https://www.spacycles.co.uk/m8b0s106p51 ... On-Dropper

https://www.sjscycles.co.uk/gear-spares ... r-dropper/

https://www.sjscycles.co.uk/gear-spares ... ter-el344/