E-Type front derailleurs and alternatives

[Mussels]

In my quest for more gear range I have been looking at fitting an extra front cog but that's difficult because the battery on my pedelec sits flush to the seat post leaving nowhere to fit a derailleur clamp. Then I saw e-type fittings which are designed not to need the seat post and to allow radical frame designs. I thought it was fantastic until I saw it needs a special thread in the seatpost, if that isn't there then the Shimano version needs a special clamp around the seat tube. That's right, to fit a special front mechanism which avoids the need for a seat tube you need to put a clamp on the seat tube!
So does anyone have any experience of these, maybe a different brand that attaches differently or something that attaches to the downtube instead?
Or how about a wildcard option that isn't practical for manufacturers but would do the job, I'd probably be quite happy using a stick with a hook on it if feasable.

 

[flecc]

I've never found anything suitable Mussels, but a very different approach is the Schlumpf drive system, a two speed bottom bracket change. Three types are available:

Schlumpf drives

They do have some drag but can solve lots of gearing problems, though very expensive.
.

 

[Mussels]

I've never found anything suitable Mussels, but a very different approach is the Schlumpf drive system, a two speed bottom bracket change. Three types are available:

Schlumpf drives

They do have some drag but can solve lots of gearing problems, though very expensive.
.

I like them and if I though they were ideal I wouldn't mind paying that when it's time to change the current cogs. However the ratio is fixed and I can't be sure that it will be suitable with the rather restricted rear options and then the high price makes it an expensive gamble.
The extra bracket for the e-type mech fits at the base of the seat tube so it may fit with minor modification but I was hoping that there may be a solution out there that uses a keyed BB or similar to avoid the need for a frame mounting at all.
I have toyed with the idea of having a double chainwheel and not bothering with the mech but instead just leaning over and moving it by hand when I get to a hilly section, is that likely to fall off a lot?

 

[flecc]

I have heard of an attachment that fits around the bottom bracket end and has an arm for the front changer. I've never seen it though, but it could seem to solve the seat tube problem.

Manual changing should be ok, quite a few have done this in the past. However, it might be possible to devise a mod on a front changer to allow it to be hand lever operated from above, with it secured to the front of the seat tube using a jubilee clip, since that would clear the battery.
.

 

[Mussels]

Chainwheel to the limit

I've done some calculations and reckon I want 36 and 52 tooth chainwheels, is that too much of a jump to be practical?
I'm planning to ditch the megarange freewheel* and put the commonly available 14-28 freewheel on the back, then I should be able to remove a couple of links for that and I'm hoping the chain won't get too slack whilst on the smaller chainwheel. Does this make sense?

* By the time I've made my mind up and get round to this I'll have probably done a couple of thousand miles so may as well change it all.

 

[flecc]

36/52 should be ok, possibly a bit slow to climb upwards. The chain length won't be a problem since a 52 to 24 triple isn't unknown, and a 48 to 24 triple common.
.