Electric conversion kit.

[[XAP]Bob]

Seems pretty free running when idle, it is internally geared, so it's not fighting the motor.

Excellent

No idea about the torque curve, but it is soft start - makes main roundabouts easy to negotiate......
Actually not really sure how to measure the torque curve at the moment...

Wasn't expecting you to measure it

Where I'm coming from (and this will prove that I'm not an electrical engineer) is on steep hills a 250W hub motor is essentially operating at a speed well below its rated 15mph. For example, some simple maths shows that on my local, mercifully not too long, 18% grade my ICE trike (all up weight of 90kg) needs about 300W for 4mph (sorry about the units), so I'm curious as to what a hub motor would put out at 25% of rated speed. I've read that some will exceed rated power under such conditions, using temperature sensing to stop internal melting (!) on long hills, but I suspect that's going to be specific to individual designs. (There are likely to be mechanical limits too.) So what I really want to know is how much assistance would I get in practice on said b*st*rd hill, as hill climbing is undoubtedly the area of weakness for my aging legs (and lungs) and the area where much time is 'lost'. If the assistance as such low speeds were 'small' then it's not really worth the hassle / weight (and I'd be better off fitting a Schlumpf MD to get a suitable crawler gear). Will be reading your experiences with interest!

Nice to hear about the soft start - are you just using it in throttle mode or do you have a BB pedal torque sensor for pedalec operation?

I suppose I could try and blag an extended test ride from a local e-bike dealer....

Pure throttle operation.
Going uphill remember that you are providing some power as well. I tended to be doing 13+mph - but I doubt any of my hills are at 18%.

If you can provide 150-200W as well the you are up over 400W..

Of course the real answer is 'try it' and the other answer is that you can get differently geared hubs - get one rated for a 26" wheel and use it in a 20" and you'll get better low speed performance.
The other 'obvious' solution is to wait until next year when ICE make their BB drive available (it was really good when I tested it - the pedal sensor was torque based, and really made the system very elegant).

[[XAP]Bob]

Seems pretty free running when idle, it is internally geared, so it's not fighting the motor.

Excellent

No idea about the torque curve, but it is soft start - makes main roundabouts easy to negotiate......
Actually not really sure how to measure the torque curve at the moment...

Wasn't expecting you to measure it

Where I'm coming from (and this will prove that I'm not an electrical engineer) is on steep hills a 250W hub motor is essentially operating at a speed well below its rated 15mph. For example, some simple maths shows that on my local, mercifully not too long, 18% grade my ICE trike (all up weight of 90kg) needs about 300W for 4mph (sorry about the units), so I'm curious as to what a hub motor would put out at 25% of rated speed. I've read that some will exceed rated power under such conditions, using temperature sensing to stop internal melting (!) on long hills, but I suspect that's going to be specific to individual designs. (There are likely to be mechanical limits too.) So what I really want to know is how much assistance would I get in practice on said b*st*rd hill, as hill climbing is undoubtedly the area of weakness for my aging legs (and lungs) and the area where much time is 'lost'. If the assistance as such low speeds were 'small' then it's not really worth the hassle / weight (and I'd be better off fitting a Schlumpf MD to get a suitable crawler gear). Will be reading your experiences with interest!

Nice to hear about the soft start - are you just using it in throttle mode or do you have a BB pedal torque sensor for pedalec operation?

I suppose I could try and blag an extended test ride from a local e-bike dealer....

It has been pointed out to me that torque is proportional to current, so a logging ammeter would be a useful thing in determining the curve...

[reohn2]

After some deliberation weve finally decided to go with the same people Bob went with,for a conversion kit for our Circe tandem:- http://www.electric-bike-conversions.co.uk/
We had a ride(in the car) to the showroom last week and was given a fair price for a front wheel kit with a 17ah battery mounted under a supplied rear rack,the whole kit weighs in at under 5kgs and should provide enough power for upto 50 miles depending on terrain.
The down side is they've no in stock of 20in front wheel kits for about five weeks,so we haven't ordered it yet but will be contacting them this week.
What concerned me was component failure,mostly motor or battery as these are the costliest bits,battery is the most expensive at £250,motor at £130 after that the most expesive bit was the lcd control panel at £50,the rest are peanuts by comarison, though Andy who I spoke to reckons all components are pretty reliable upto about 10k+miles,but as were no longer high mileage users and are able to choose our weather options we felt confident with this company after chatting with a very down to earth owner who knows his stuff,plus the whole kit is guaranteed for 12 months.
I'll be sending off an email and wait for the kit to arrive,watch this space for further updates

[groberts]

After some deliberation weve finally decided to go with the same people Bob went with,for a conversion kit for our Circe tandem:- http://www.electric-bike-conversions.co.uk/
We had a ride(in the car) to the showroom last week and was given a fair price for a front wheel kit with a 17ah battery mounted under a supplied rear rack,the whole kit weighs in at under 5kgs and should provide enough power for upto 50 miles depending on terrain.
The down side is they've no in stock of 20in front wheel kits for about five weeks,so we haven't ordered it yet but will be contacting them this week.
What concerned me was component failure,mostly motor or battery as these are the costliest bits,battery is the most expensive at £250,motor at £130 after that the most expesive bit was the lcd control panel at £50,the rest are peanuts by comarison, though Andy who I spoke to reckons all components are pretty reliable upto about 10k+miles,but as were no longer high mileage users and are able to choose our weather options we felt confident with this company after chatting with a very down to earth owner who knows his stuff,plus the whole kit is guaranteed for 12 months.
I'll be sending off an email and wait for the kit to arrive,watch this space for further updates

Glad to hear you're going to go ahead, it will be interesting to see how the kit performs on a tandem - I presume you'll need longer power and control leads? My own conversion continues to be excellent and has had a major positive impact, it's a real pleasure to getting some miles in again with a little assistance from my electric stoker from time to time; with the PAS you still get to cycle but just get a bit of relief where and when you need it. On the flat I mostly turn off the assistance completely or have it on a low setting - I have the LCD version + it's worth fitting the thumb throttle as an alternative quick squirt of power at critical moments too.

I't's still very early days but the kit seems good and the motor and wheel is well put together; I'll provide an update after a few months use. I would recommend getting the clip-type PAS sensor (which I'm using) that fits on the seat tube as well as the standard metal ring type as an option. I was told that the battery life is about x1,000 charges, so it is important to keep a record and maybe after say x900 maybe need to think about replacing or at least getting a spare. After three full charge cycles and using as outlined above I seem to be getting about 50 to 60 miles on varied terrain with the 17Ah version.

Let us know how you get on + good luck.

Graham

PS thanks to the moderators for the new Electric Bikes section

[reohn2]

Graham
Thanks for the pointers I'll bear them in mind andnas you say thanks to the moderators for this additional section to the forum,I'm sure it'll be a success

[[XAP]Bob]

1000 charges is about 4 years of daily recharging - assuming that the charge limit is approximately pro-rated (i.e. you can charge 2000 times if you charge from 50%-100% each time) then you might expect even more out of the battery.

If the 'life' is determined by the point at which capacity is at 80% then you might get significantly more, I don't know how fast capacity drops...

[Marc]

Of course the real answer is 'try it' and the other answer is that you can get differently geared hubs - get one rated for a 26" wheel and use it in a 20" and you'll get better low speed performance.

There are no 'differently geared hubs'. The gear ratio in 20" or 28" geared hub motors (of the same model) is always the same.
The difference is in stator winding (the number of copper wire windings around the stator) and hence the motor rpm per volt, that results in the speed difference.

1000 charges is about 4 years of daily recharging - assuming that the charge limit is approximately pro-rated (i.e. you can charge 2000 times if you charge from 50%-100% each time) then you might expect even more out of the battery.

Not exactly. Most battery cell manufacturers rate battery life by 500 full charging circles (from 2.7V to 4.2V) till battery capacity drops to 80%.
You can prolong (roughly double) the usable service life of a lithium battery by charging only to 90% (eg charge to 4.1V per cell, instead of 4.2V per cell).
To further extend service life, you don't deplete the battery down to 2.7V per cell, but only deplete the battery down to 3V per cell (about 20% of charge. Recharging at 3.2V per cell is even better.

I'm an ebike commuter for seven years now.
Hence I always give the advice to get a battery with at least twice the battery capacity you actually need for your commute.
You charge to 90% and recharge at 40-50%. As a rule of thump, this will quatruple the service life of your battery (its the same technic electric car manufacturers use) and even when the battery capacity is down to 60% after a couple of years, you're still able to use it for the commute.
Works for me.

Have a look here: http://www.ebikes.ca/tools/charge-simul ... ial-charge
The Charge Simulator (and charge profile 'generator') is a web application for the Grin Tech Cycle Satiator (arguably one of the best ebike chargers out there). http://www.ebikes.ca/product-info/cycle-satiator.html

[Geoff.D]

.......................
I'm an ebike commuter for seven years now.
Hence I always give the advice to get a battery with at least twice the battery capacity you actually need for your commute.
You charge to 90% and recharge at 40-50%. As a rule of thump, this will quatruple the service life of your battery (its the same technic electric car manufacturers use) and even when the battery capacity is down to 60% after a couple of years, you're still able to use it for the commute.
Works for me.

Have a look here: http://www.ebikes.ca/tools/charge-simul ... ial-charge
The Charge Simulator (and charge profile 'generator') is a web application for the Grin Tech Cycle Satiator (arguably one of the best ebike chargers out there). http://www.ebikes.ca/product-info/cycle-satiator.html

Thanks for this info. Straightforward for a non-electrical minded person like me.

[[XAP]Bob]

.......................
I'm an ebike commuter for seven years now.
Hence I always give the advice to get a battery with at least twice the battery capacity you actually need for your commute.
You charge to 90% and recharge at 40-50%. As a rule of thump, this will quatruple the service life of your battery (its the same technic electric car manufacturers use) and even when the battery capacity is down to 60% after a couple of years, you're still able to use it for the commute.
Works for me.

Have a look here: http://www.ebikes.ca/tools/charge-simul ... ial-charge
The Charge Simulator (and charge profile 'generator') is a web application for the Grin Tech Cycle Satiator (arguably one of the best ebike chargers out there). http://www.ebikes.ca/product-info/cycle-satiator.html

Thanks for this info. Straightforward for a non-electrical minded person like me.

It is good - but also quite hard to do anything with in most cases - I have no idea what the BMS does on my bike battery...

[Marc]

It is good - but also quite hard to do anything with in most cases

You just need a charger that doesn't charge your battery to 100%. Or monitor the charging voltage and pull the plug.

Actually, most (cheap) BMS need to charge the battery to 100% to do the cell balancing. It's quite enough if you only charge the battery to 100% for cell balancing every tenth or twentieth time (or once a month maybe).

I have no idea what the BMS does on my bike battery...

It keeps your battery healthy. Isn't that enough to know?

A BMS no rocket science. Depending how sophisticated it is, it:
- prevents the battery voltage to drop below a certain point (low voltage protection)
- prevents the battery to get charged to a too high voltage (over charge protection)
- keeps the battery cells at the same cell voltage (cell balancing)
- has a fuse

[[XAP]Bob]

Yep, but I have nonidea what the battery does - I think the charger just outputs a certain voltage, and changes the colour of an LED changes when there is sufficient back Voltage / insufficient current.
In the battery there is a fuse, some circuitry, and a power switch...

[Cunobelin]

Hi,
Please elaborate, I want one for er indoors so she can keep up
I gather that the battery is the biggest cost

On my Christiania.... £700

[hemo]

For commuting and general road riding or a town errand bike then a rear hub motor with pas/cadence sensor makes for a leisurely relaxed ride, if you are sportier cyclist then a mid drive is more like a normal bike and requires you to be in the correct gear and generally a better option for off-road riding.
Mid drives available in pas/cadence or torque sensor dirve.
Pas/cadence generally just needs a gentle pedal rotation for a boost in power where as a torque sensor delivers the power to match the effort you put in.

Hub kits are ideal if you like fettling and getting the spanners out, axles are 10 x12 mm so unlike most qr axles of 9mm do require the dropouts front or rear to be filed 3 or 4mm deeper so that the axle nuts actual tighten in the drop out properly. Also the axles have a small anti rotation washer with a right angled tab this also needs to sit in the drop out hence the need to file the drop out deeper, in addition if you are fitting to aluminium frames you should fit a torque arm as an aid to resist the hub from twisting out of the drop outs.
Not doing so could result in a nasty face plant in the event a hub drive should decide to twist out due to torque.
When mounting a hub drive the hub cable entry should always exit pointing down with the cable forming a drip loop this prevents water tracking in to the hub and seizing it up.

[Cunobelin]

Guessing that it won't fit a sclumpf hsd though

Technically 350W isn't road legal either...
I am considering a B version for the trike though. Which did you get?

You can put a double on a Shlumpf, by fitting the spider version and a ring on either side

[Tigerbiten]

You can put a double on a Schlumpf, by fitting the spider version and a ring on either side.

It's easy to fit double chainrings on all Schlumpf drives but it's the High Speed Drive that's not so simple in practice.
I run 54/38 chainrings on my HSD.
The 130 BCD spider on the HSD is only held in place by a circlip, so that limits the minimum chainring size to 38 teeth to start with.
Get the change wrong and put too much sideways pressure on the chainrings and you can pop the circlip.
So I treat the change between chainrings as another hub gear change and change under minimum load.
It's been a while since I last lost my drive, but I do lose a lot of momentum if changing going uphill.