Front Derailleur Adaptor

[AlanW]

I've decided to fit a 30/46 sub compact chainset onto my steel framed bike. However, the one slight problem l can see is that the front mech has a brazed on mount and the mech is already as low as it can go with the current 34/50 chainset.
Which means ideally l probably need to put a front mech extender on in order the drop the mech low enough.
Has anyone got any experience in doing this and if so was it successful?
There also seems to be a couple of options in the design of the adaptors, either parallel or with a 4 degree taper. What's the advantages or disadvantages with either?
I would have thought that a plain parallel one would do the job, as l only need to lower the mech by a few mm.
Any advice would be gratefully received before l start hacking everything to pieces !

 

[GuyBoden]

I've decided to fit a 30/46 sub compact chainset onto my steel framed bike. However, the one slight problem l can see is that the front mech has a brazed on mount and the mech is already as low as it can go with the current 34/50 chainset.
Which means ideally l probably need to put a front mech extender on in order the drop the mech low enough.
Has anyone got any experience in doing this and if so was it successful?
There also seems to be a couple of options in the design of the adaptors, either parallel or with a 4 degree taper. What's the advantages or disadvantages with either?
I would have thought that a plain parallel one would do the job, as l only need to lower the mech by a few mm.
Any advice would be gratefully received before l start hacking everything to pieces !

A few mm will probably not matter in the slightest, the chainrings will probably work ok.

 

[AlanW]

A few mm will probably not matter in the slightest, the chainrings will probably work ok.

I think you are right to be honest but just in case its not as crisp as it should be, lm exploring possible options.

 

[ianrauk]

Another recent thread here asking the same question

 

[AlanW]

A few mm will probably not matter in the slightest, the chainrings will probably work ok.

Well, I did 50 miles today with the front mech in the original position and it worked perfectly to be honest. I guess that the front mech is probably 10mm higher than you would normally have it, but it didn't appear to make any difference what so ever.

 

[Ajax Bay]

Great. Just be aware that with that vertical gap there's an increased risk of the chain over shifting and 'falling off' on the outside.
Mitigations: have the H limit screw so it only just allows the upshift (with the chain in smallest sprocket).
Don't up shift 'enthusiastically' and always with an ease off of pedalling force.
Also worth checking when cross-chaining in small small that the chain is vertically clear of the pin/bolt at the back of the FD cage, and if not avoid / recognise the sound.

 

[AlanW]

One step ahead of you, H screw wound in as close as l can get it, and yes, no swinging on the shifter when changing the front chain rings.