Running out of electricity on my ICE Q and spider for two chainrings?

[nobby]

I have fitted a Bafang 250W bottom bracket drive to my 2009 ICE Q and a 36V 15Ah battery with a Shimano Alfine 11 IGH in the rear wheel (similar set up to Aunty Helen whose blog has been a treasure trove, and I wish I had taken more notice about the speed sensor extension cables).
This is to be my return to touring cycling in the Welsh borders (I hope) and I've been thinking about what happens if I use up the battery before I have arrived at my night's rest - probably a campsite. With the Bafang standard 46T chainring my bottom gear is 23" and I need a lot less than that to get a camping loaded Trice up the many Welsh foothills.
Carrying a spare battery is an obvious solution but they are weighty, bulky & expensive items.
It is possible to get an after market spider for the Bafang which allows the fitting of two chainrings. They are available in 104 BCD and I have a pair of chainrings in 44 and 32T which will give me a sufficient gear range.
My thinking is that in the event of a dead battery I would move the chain across to the smaller chainring, manually, and adjust the chain tensioner to suit.

There's bound to be a flaw in my thinking and if anybody can point it out I'd be grateful. Cheers

[andrew_s]

"Chain tensioner" sounds like it's only intended to cope with chain wear (aka stretch), and in may not offer enough take up to cope with 12T plus wear.
If I'm correct, fit two quick links 6" apart, so you can easily remove the intervening section. You'll maybe also want to add some latex gloves and a quick link tool)

[nobby]

"Chain tensioner" sounds like it's only intended to cope with chain wear (aka stretch), and in may not offer enough take up to cope with 12T plus wear.
If I'm correct, fit two quick links 6" apart, so you can easily remove the intervening section. You'll maybe also want to add some latex gloves and a quick link tool)

Thanks Andrew. That's a clever idea

[Polar Bear]

There are people out there making bigger batteries.   Personally I'd carry a second battery if I needed more range.

[pdm]

Alternatively, you could always try a single speed chain tensioner, e.g.like this one, you can then fit a dérailleur on the front chain ring and use the whole range of gears at all times.....

[numbnuts]

It is possible here
https://www.youtube.com/watch?v=bpBxfhn0Px0&feature=youtu.be
adapter plate
https://ozo-electric.com/en/e-bike-kits/639-dual-chainwheel-road-kit-for-bafang-bbs01-bbs02-mid-drive-motor

[Kim]

There are people out there making bigger batteries.   Personally I'd carry a second battery if I needed more range.

+1

Any plan that involves deliberately running out of power is silly: If you can carry the deadweight, you don't need the assistance in the first place.

Carry more battery, ride less far, use more human power or stop and recharge.


As for chain tensioners, you can take far more liberties with capacity on recumbents.  On barakta's Sprint (which has the chain a few links too long so I can extend the boom to fit me), the weight of the slack chain in its tube creates enough tension to keep everything working properly in small:small as long as you don't backpedal too much.  You only use small:small to keep the derailleur from eating grass on campsites anyway.

[andrew_s]

Alternatively, you could always try a single speed chain tensioner, e.g.like this one, you can then fit a dérailleur on the front chain ring and use the whole range of gears at all times.....

That style of chain tensioner won't take up 6" of chain. Something with 2 idlers, as per a rear derailleur, would be needed (e.g. this Alfine tensioner), though where you'd fit it on an ICE Q I don't know.

[Kim]

Alternatively, you could always try a single speed chain tensioner, e.g.like this one, you can then fit a dérailleur on the front chain ring and use the whole range of gears at all times.....

That style of chain tensioner won't take up 6" of chain. Something with 2 idlers, as per a rear derailleur, would be needed (e.g. this Alfine tensioner), though where you'd fit it on an ICE Q I don't know.

Just use a derailleur, and remember to clean it occasionally.

[nobby]

There are people out there making bigger batteries.   Personally I'd carry a second battery if I needed more range.

+1
Any plan that involves deliberately running out of power is silly: If you can carry the deadweight, you don't need the assistance in the first place.

Carry more battery, ride less far, use more human power or stop and recharge.

As for chain tensioners, you can take far more liberties with capacity on recumbents.  On barakta's Sprint (which has the chain a few links too long so I can extend the boom to fit me), the weight of the slack chain in its tube creates enough tension to keep everything working properly in small:small as long as you don't backpedal too much.  You only use small:small to keep the derailleur from eating grass on campsites anyway.

The battery I have came with the kit and I would prefer not to buy another either as a replacement or as a spare.
I'm not planning on deliberately running out of battery but I am hoping to be covered against it happening. I'm told this battery is good for 40 mile but, presumably, that depends on person, weight carried and hilliness. Aunty Helen reported 75 miles over two days from her battery but I'm not sure what Ah that is. I'll be happy enough to cover 40 miles a day; that leaves time in the day for exploring history, topography and cafes.
"If you can carry the deadweight, you don't need the assistance in the first place." What do you mean by deadweight?

[nobby]

Alternatively, you could always try a single speed chain tensioner, e.g.like this one, you can then fit a dérailleur on the front chain ring and use the whole range of gears at all times.....

That style of chain tensioner won't take up 6" of chain. Something with 2 idlers, as per a rear derailleur, would be needed (e.g. this Alfine tensioner), though where you'd fit it on an ICE Q I don't know.

Thanks, I do have one of those in a box. If I go for the two chainring option I will fit it

[Kim]

"If you can carry the deadweight, you don't need the assistance in the first place." What do you mean by deadweight?

The additional weight of the non-functioning battery, motor, etc.

[nobby]

"If you can carry the deadweight, you don't need the assistance in the first place." What do you mean by deadweight?

The additional weight of the non-functioning battery, motor, etc.

Ah, thanks for that.