Extra gears on a Wisper

[Mussels]

I have all the gears I need on the Wisper but not all the gears I would like. I accept that with a rear hub motor I'm not going to get more than the 7 speed freewheel that is there, struggling to squeeze an 8 speed in wouldn't really improve things much.
So I'd like to change chainrings but all the normal ways to fit a front mech seem to be useless on the Wisper.
I can't use a braze on mech as there's no brazed on mounting point, are they even possible on an Aluminium frame?
I can't use a clamp on mech as the battery sits snugly to the seat post.
I can't use an underslung mech (for full suspension bikes with little seatpost) because it needs a special fitting on the down tube.
There are threaded holes on the seat tube to take the pump holder and I guess I could make a braze on fitting that clamps there, it would be a lot of work and no guarantees that it is strong enough.
I imagine many other bikes have the same problem, Synergie, Ezee etc. Anyone any ideas on how this could be done?

 

[flecc]

If the bottom bracket is standard, the Schlumpf two speed speed drive or mountain drive will do the job:

Schlumpf at BikeFix

A great solution, but at a very high price.
.

 

[Mussels]

If the bottom bracket is standard, the Schlumpf two speed speed drive or mountain drive will do the job:

Schlumpf at BikeFix

A great solution, but at a very high price.
.

Did I mention my budget doesn't stretch to the cost of a new bike.

 

[flecc]

Did I mention my budget doesn't stretch to the cost of a new bike.

No, but I did warn of the price.

Florian Schlumpf obviously rates his invention and quality Austrian engineering highly.

Your problem is common to the eZee models and many others, and a solution for a front derailleur is possible. What's needed is a thin bar attachment that clamps to the foot of the down tube from the headstock, with adjustable length, and the other end a lined yoke that goes against the seat tube ahead of the battery. That could carry the front derailleur chain channel and changer.

Although I've never seen one, I understand that at one time Shimano made front changers that mounted at the side of the bottom bracket, basically a mechanism mounting plate that was held in place by the BB locking nut. That would also be ideal of course. It might be possible to fabricate one of those.

Here's a pic from a US patent application showing the same idea:

Drawing
.

 

[torrent99]

Did I mention my budget doesn't stretch to the cost of a new bike.

In passing I've thought of this...(I can't use 1 gear let alone 14!) If you can get a clamp on that will fit around the downtube, then you could just have a higher battery! Put a block of foam underneath to stop the battery banging on the deraileur bracket. Of course this might not work if your seat is low (mine is on the max setting of a 400mm seat post so I can slide the battery in and out without touching the seat ).

This lack of easy downtube access is a real problem on rocket launcher style bikes. For example the most commonly available child seat style (e.g. the Hamax kiss) needs a downtube clamp too.

 

[flecc]

Found the Shimano one on this site now.
.

 

[Mussels]

Although I've never seen one, I understand that at one time Shimano made front changers that mounted at the side of the bottom bracket, basically a mechanism mounting plate that was held in place by the BB locking nut. That would also be ideal of course. It might be possible to fabricate one of those.
.

I looked at those and thought it was the answer but I found they needed to bolt on to the downtube so the frame had to be designed for it.
Edit: I have found that the braze on required can be replaced by a Problem Solvers E-clamp which would bring the price for the whole mech up to about £50-£60, that's affordable but I think hard to find and hard to fix if it breaks. It may need a special BB as well, I need to do some more reading as I certainly can't afford it all now.

In passing I've thought of this...(I can't use 1 gear let alone 14!) If you can get a clamp on that will fit around the downtube, then you could just have a higher battery! Put a block of foam underneath to stop the battery banging on the deraileur bracket. Of course this might not work if your seat is low (mine is on the max setting of a 400mm seat post so I can slide the battery in and out without touching the seat ).

This lack of easy downtube access is a real problem on rocket launcher style bikes. For example the most commonly available child seat style (e.g. the Hamax kiss) needs a downtube clamp too.

I have hit a wall with the child seat problem as well but given up on that for now.
Raising the battery would work for me as I have the seat as high as it goes, problem is I need to be able to lock the battery to the bike and this won't work unless I modify the battery. If I can work out a way to lock the battery so it's not easily forced that may be the way ahead, time to think and ponder....

 

[flecc]

I looked at those and thought it was the answer but I found they needed to bolt on to the downtube so the frame had to be designed for it.

Yes, but i wonder if a clip could be used on the downtube to provide a support point in lieu?
.

 

[Mussels]

Yes, but i wonder if a clip could be used on the downtube to provide a support point in lieu?
.

I edited my post as you wrote this, I found the answer above.

 

[flecc]

I edited my post as you wrote this, I found the answer above.

That's good, at least it's more hopeful now and not in millionaire territory.
.

 

[Mussels]

That's good, at least it's more hopeful now and not in millionaire territory.
.

This will hopefully be my summer project now, I want to have good weather to break down in if (when) it goes wrong.