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The Eagle

Push Bike Electric Conversion, Anyone Done This?

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I was thinking of converting my push bike (bog standard 26" Halfords mountain bike with aluminium frame, 24 gears, front suspension and front disk brake) to an electric bike, as here where I live it's all hills.

I have been doing some research in conversion kits but the choice is bewildering so I'm a bit lost.

Has anyone done this and can give some good pointers?

Any recommendations of good kits, good motors (500W seems best for my needs), durable battery packs and anything else related would be most welcome.

I will only be using the converted bike on tarmac, no off-road use.

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Plenty of information on this site: http://www.pedelecs.co.uk/content.php

There are some knowledgeable people using the forum there too.

Yes, that's one of the forums I came across during my research, it has useful info but some of it is way over my head due to extensive use of acronyms that I have no idea what they mean.

Also many of these forums appear to be oriented more towards hard core bikers so needs and expectations seem to differ from mine (for example US forums seem to focus on 1000W 48V motors which are illegal over here).

I think that for road use the legal limit is 250W.

Luckily in Switzerland (where I currently live) it's 500W with the additional provision that engine support cuts out when the bike has reached 25km/h.

I was thinking of a 500W motor not because of speed but because I want adequate power to go effortlessly up-hill. B)

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Have a look at the "commuter booster" google it. works by spinning a radio controlled motor onto the tyre. very hard to get hold of one though.

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My wife used to use a Heinzmann (sp) powered hub and NiCad battery. All retrofitted to a cruddy hybrid.

Worked fantastically and kept her mobile when she had to lug around a trailer full of children and shopping (we live in a valley so there's a hill wherever you're headed - except the beach).

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Have a look at the "commuter booster" google it. works by spinning a radio controlled motor onto the tyre. very hard to get hold of one though.

Interesting thanks, but like you say unfortunately it doesn't seem to be readily available.

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i owned a Heinzmann/ NiCD converted full-size folding mountain bike (dahon matrix) for a while built by Kinetics of Glasgow.

it was 250W street-legal but had no problems going up hills -- i believe it peaked at 400w or so for short bursts -- and i lived in a hilly area then.

i ended up selling it as i was living in a terraced house at the time and despite being a folder, it was still a heft to get it though the house.

made a 50% profit over what i originally paid on ebay, it being pretty much a one-off, and Heinzmann + sanyo cells are well-regarded.

it was fun while i had it but wouldn't be any use to me now as i've since moved to a south coast town that is almost entirely on the flat!

... although i do now have a side entrance.

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Best bet at the moment is probably picking up a ready built second hand with working motor and upgrading the battery pack. If you go for hub drive quite a lot of issues with mounting in the forks and not ripping the dropouts apart, sizing etc. Mounted to the rear - more issues with mouting and fit, getting a wheel re-spoked either way maybe.

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Best bet at the moment is probably picking up a ready built second hand with working motor and upgrading the battery pack. If you go for hub drive quite a lot of issues with mounting in the forks and not ripping the dropouts apart, sizing etc. Mounted to the rear - more issues with mouting and fit, getting a wheel re-spoked either way maybe.

I did look around for second hand ebikes but there are very few available locally and they cost as much or more than a conversion kit (and the ones I saw were only 250W). Also I don't really want another bike cluttering up my place.

If I get a hub motor I would certainly get it already fitted inside a wheel, I would only do the mounting onto the bike which should be ok, I mean I have experience with changing and fixing bike tyres so swapping out the wheel with a new one shouldn't be a problem.

Heinzmann motors have so far been mentioned twice in this thread and I see they are made in Germany which should mean better quality than the Chinese motors that I see everywhere, but I'm struggling to find resellers who sell Heinzmann motors locally.

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I did look around for second hand ebikes but there are very few available locally and they cost as much or more than a conversion kit (and the ones I saw were only 250W). Also I don't really want another bike cluttering up my place.

If I get a hub motor I would certainly get it already fitted inside a wheel, I would only do the mounting onto the bike which should be ok, I mean I have experience with changing and fixing bike tyres so swapping out the wheel with a new one shouldn't be a problem.

Heinzmann motors have so far been mentioned twice in this thread and I see they are made in Germany which should mean better quality than the Chinese motors that I see everywhere, but I'm struggling to find resellers who sell Heinzmann motors locally.

Have a look at kinetics' website.

http://www.kinetics.org.uk

EDIT: oops, looks like kinetics don't do the Heinzmanns anymore.

this is why they are superior though,

Heinzmann kit

- All Heinzmann hub motors are brushed-DC motors - the type Heinzmann have tested extensively and know are tough and reliable. These drive a two-stage gearbox, which drives the wheel through a roller clutch - so there’s absolutely no drag when the motor is not being used, and because the motor is brushed it’s also very smooth - there’s no “cogging” (notchiness in the power).

- All Heinzmann motors are built to the same basic plan, for front or rear wheel fitting. The motor is spoked directly into the rim,

So why is the Heinzmann motor so good? Read on, and be warned - this may get a bit technical!

- The Magnets: The magnets in a motor are one half of the torque-producing system - they produce the magnetic field which the coils act against. The stronger a field you can fit into a small space, the better. Heinzmann only use the best quality rare-earth magnets, for the highest possible magnetic flux density.

- The Coils: The coils are the other half of the system - and the trickiest bit! The trick is to fit as many coils in as possible, able to carry the largest current you can manage. Heinzmann’s coil designs are very sophisticated (and very secret!), but manage to squeeze in a lot more power than all the textbooks say is possible - up to 3 horsepower in some motors!

- The Bearings: The bearing which a motor and gearbox run on are vital - they are going to get a lot of abuse and no maintenance! Heinzmann only use genuine SKF sealed bearings, not cheaper far-eastern imitations.

- The Gears: The gears are the only real wearing parts in a motor and gearbox, so they have to be good. Heinzmann’s are made out of hardened steel, with a helical tooth pattern to reduce wear.

- The Castings: Although it’s bigger than a standard hub, there’s no superfluous metal in the Heinzmann hub - everything is machined down to save weight without sacrificing strength.

- The Thermistor: This is the bit almost all other systems miss out! The Heinzmann motor has a built-in thermistor which keeps an eye on the motor temperature.

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I did look around for second hand ebikes but there are very few available locally and they cost as much or more than a conversion kit (and the ones I saw were only 250W). Also I don't really want another bike cluttering up my place.

If I get a hub motor I would certainly get it already fitted inside a wheel, I would only do the mounting onto the bike which should be ok, I mean I have experience with changing and fixing bike tyres so swapping out the wheel with a new one shouldn't be a problem.

Heinzmann motors have so far been mentioned twice in this thread and I see they are made in Germany which should mean better quality than the Chinese motors that I see everywhere, but I'm struggling to find resellers who sell Heinzmann motors locally.

From what i've read before it seems the Heinzmann are excellent motors but expensive.

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I was thinking of converting my push bike (bog standard 26" Halfords mountain bike with aluminium frame, 24 gears, front suspension and front disk brake) to an electric bike, as here where I live it's all hills.

I have been doing some research in conversion kits but the choice is bewildering so I'm a bit lost.

Has anyone done this and can give some good pointers?

Any recommendations of good kits, good motors (500W seems best for my needs), durable battery packs and anything else related would be most welcome.

I will only be using the converted bike on tarmac, no off-road use.

As an alternative could go down the weight weenie route. Super lightweight carbonfibre frame and forks, lightweight quality wheels, carbon parts all around. could get it under a stone in weight (decent 2nd hand bike) for the same price as a good electric kit and bike. Would be better for riding downhill too. Would still be hard work uphill but quicker than just a heavy mountainbike.

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I looked into this last year; my bike is a Cotic Roadrat with a Shimano Alfine rear hub (no derailleur/sprockets).

After a bit of research decided it was generally simpler to get an electric hub motor front wheel rather than muck about with fitting a powered rear wheel due to possible gearing compatibility issues.

Ebay UK are selling 26 inch and 700c "8fun" brand front wheels for £429 all in including battery, wiring and controller. They are Chinese made but had a few recommendations from the ebike forums. Disc brake compatible versions available, battery is waterbottle shaped and carried in the bottle holder on your down tube.

This seems quite good value, didn't get one in the end, still might though. No connection with sellers.etc.

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would need the front forks beefed up though otherwise would snap the dropouts with the torque.

Good point though don't recall reading anything about this; Roadrats however are known for their chunky, fugly forks plus the front dropouts are angled forward (to stop the disc brakes torquing the wheel out under heavy braking) so prob not an issue for me :-).

Another advantage of a front powered wheel is that with the rear powered wheels you usually have to mount the battery on your rear carrier which to me is ugly and puts a lot of weight on the back, stressing the wheel and losing carrying capacity.

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would need the front forks beefed up though otherwise would snap the dropouts with the torque.

Yes, that's the other thing, I'm undecided whether to get a front wheel motor or a rear wheel motor. I'm tending towards a rear wheel motor as that seems the better choice, although I'm afraid of compatibility issues which seem more likely on the rear.

With regards to the battery pack I was thinking about a bottle type one that can be attached in place of a drinking bottle inside the frame triangle. Any opinions on that?

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if i were building a new electric bike today i'd probably base it on a pared-down lightweight single-speed (freewheel) hybrid with either a hub motor in the front or one of the new friction-drives on the rear,

such that it could all be easily removed to leave me with a lightweight traditional bike.

gears are overrated.

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if i were building a new electric bike today i'd probably base it on a pared-down lightweight single-speed (freewheel) hybrid with either a hub motor in the front or one of the new friction-drives on the rear,

such that it could all be easily removed to leave me with a lightweight traditional bike.

gears are overrated.

depends where you live. but i know where you're coming from.

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I looked into this last year; my bike is a Cotic Roadrat with a Shimano Alfine rear hub (no derailleur/sprockets).

After a bit of research decided it was generally simpler to get an electric hub motor front wheel rather than muck about with fitting a powered rear wheel due to possible gearing compatibility issues.

Ebay UK are selling 26 inch and 700c "8fun" brand front wheels for £429 all in including battery, wiring and controller. They are Chinese made but had a few recommendations from the ebike forums. Disc brake compatible versions available, battery is waterbottle shaped and carried in the bottle holder on your down tube.

This seems quite good value, didn't get one in the end, still might though. No connection with sellers.etc.

I used to run an electric bike. Used a kit I bought from a place in Cambridge (think it was something like The Electric Transport Shop). It used an 8fun motor 350W I think. The 24V lithium battery I got with the kit was rubbish so I bought a 36V Nimh battery from 50 cycles. My 24 Volt controller coped just fine with 36V (I checked inside to verify the capacitors were rated at min 50V). I also bought a 36V controller from ecrazyman on eBay as a replacement/spare.

I fitted the kit to a cheap steel frame mountain bike as I needed to bend the rear forks a bit to fit the motor. It was a rear wheel motor kit and would only accept a 5 to 7 speed rear gear (I don't think any will take the 8 or 9 speed rear cogs) . Even with a 6 speed gear it was still about 145mm wide which is more than the usual 130mm rear forks on most mountain bikes.

I mounted the battery in a custom made bracket which I put on the downtube using the water bottle mounts. I used the throttle that came with the kit and didn't have a pedal operated sensor as many kits do.

The bike was really fast, easily capable of 22-24mph on the flat with no pedalling. It made short work of hills too. The only problem was range. I could do the 15 miles to work in 48 minutes flat if I gave it lots of throttle all the way. That would discharge the battery and I would have to charge it up during the day at work (bit of a pain as I had to carry the charger with me - they were £50 each so I should have bought another). The same route on my non-assisted bike would take me around 1hr 15 mins so the electric kit chopped of 27 mins which is not bad.

Overall the battery and motor made the bike really heavy (it wasn't that light to start with). I think I would have preferred a properly designed ebike. It would also have been more of a long term prospect if I had a shorter journey to work so I wouldn't have to faff about with charging the battery during the day. Adding in the fact that I had to drag the monster bike through the house from the garden each day to get it out meant that it was a fairly short lived hobby.

Also if I had a shorter journey to work I don't think I'd bother with an ebike since they don't handle very well with all that weight. They also don't ride we'll when you aren't using the throttle. The motor produces some resistance or drag when turning with no power, the bike just does not freewheel that well. I think this is true of all ebikes.

If I got one again I would go for a much higher capacity battery. Mine was 9Ah and I would think a 15Ah+ battery would be a more sensible option. However a higher capacity battery may be too heavy. One that works through the gears like the Panasonic motors may be a better option too. As someone mentioned earlier a friction drive type thing may be an option as then you could totally remove the kit and use it as a normal bike.

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Thanks gardener, that's an interesting first hand experience report.

Did you ever weigh your kit? How much weight did it add?

I have seen some 500W motors that only weigh 3kg and 6/8Ah LiFePO4 battery packs that are also around 3/4kg so my estimate would be that the whole conversion could weigh around 8kg which I don't think is that much, especially considering that my bike has an aluminium frame so is rather light to begin with.

On the other hand I have seen that cheaper ebikes are around 25-30kg (which is considerably more than I expect my converted bike would be) while the more expensive ones cost way too much for my budget.

With regards to motor resistance, I read that that's only the case with direct drive motors not with geared motors (correct me if I'm wrong).

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Heinzmann kit

- The Gears: The gears are the only real wearing parts in a motor and gearbox, so they have to be good. Heinzmann’s are made out of hardened steel, with a helical tooth pattern to reduce wear.

Thanks for the details, I just spoke to a local ebike specialist and he also confirmed that Heinzmann motors are very good quality and therefore very durable, the problem is they are a lot more expensive than even the reputable Chinese alternatives (fair enough, I guess you get what you pay for) and more importantly the fact that they use hardened steel gears is not purely positive.

While hardened steel gears are next to indestructible (which is great), the problem is (according to the specialist I spoke to) they produce a rather loud whiny noise during use (no stealth ebiking with these motors). Did you notice this?

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Thanks for the details, I just spoke to a local ebike specialist and he also confirmed that Heinzmann motors are very good quality and therefore very durable, the problem is they are a lot more expensive than even the reputable Chinese alternatives (fair enough, I guess you get what you pay for) and more importantly the fact that they use hardened steel gears is not purely positive.

While hardened steel gears are next to indestructible (which is great), the problem is (according to the specialist I spoke to) they produce a rather loud whiny noise during use (no stealth ebiking with these motors). Did you notice this?

yes, mine was noticeably hummy under throttle.

but no drag when idle.

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Thanks gardener, that's an interesting first hand experience report.

Did you ever weigh your kit? How much weight did it add?

I have seen some 500W motors that only weigh 3kg and 6/8Ah LiFePO4 battery packs that are also around 3/4kg so my estimate would be that the whole conversion could weigh around 8kg which I don't think is that much, especially considering that my bike has an aluminium frame so is rather light to begin with.

On the other hand I have seen that cheaper ebikes are around 25-30kg (which is considerably more than I expect my converted bike would be) while the more expensive ones cost way too much for my budget.

With regards to motor resistance, I read that that's only the case with direct drive motors not with geared motors (correct me if I'm wrong).

I never weighed it but I would estimate it to have been over 30 kilos. That's an awful lot more that my 13 kg mountain bike (minus all the extra stuff carried eg water, pump etc).

My motor was a geared one and it still had drag, not terrible drag but enough to notice. Perhaps it wasn't mostly actual drag from the motor but more the cheap bike I mounted it on. Either way it just didn't seem to freewheel down a hill as well as my nice Marin with a new quality drivetrain.

My battery was HEAVY. Not sure of the exact kg but it felt like a ton, definitely more than 5kg, probably 7 or 8kg.

I think one of the Panasonic motors that mount near the bottom bracket and thus leave your quality shimano hubs and freewheels alone might be a better bet.

I think unless you can get a very lightweight bike you may be disappointed. Anything that's too heavy compared to a nice quality MTB or hybrid is going to handle like a pig and won't really feel like a bike. If you can keep the weight down and accept that you will not be going off road at all (especially as you'll want slicks or near-slicks to reduce rolling resistance to a minimum) then I reckon you could make a nice ebike. It won't be cheap though.

Try as many out as you can before you buy.

Oh, I also had a kit where the motor mounted on the back wheel via the spokes and drove the bike that way. Can't remember the name of it but that was quite good. It was incredibly noisy though and that put me off a bit. On balance I preferred the hub motor kit which was pretty stealthy, with only a slight low pitched whine.

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the problem with hub motors as others have pointed-out is that you need beefy forks which necessitates a heavy bike.

the new rear-wheel friction motors that engage only when throttled, on the other hand, should be able to work on a lightweight frame.

i don't think they are suitable for extended power-on, and they probably slip in the rain but i would anticipate using mine for short bursts (up hills or to get up to speed) and only in the dry (i'd get the bus otherwise!).

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I think one of the Panasonic motors that mount near the bottom bracket and thus leave your quality shimano hubs and freewheels alone might be a better bet.

From what I could find out (correct me if I'm wrong please) the Panasonic motors can't be retrofitted, the frame must be designed to accommodate them.

I just weighted my bike and it's 14.2 kg, so if an ebike kit adds another 8kg I think the handling would still be acceptable, especially since the heavy parts would be placed rather low, motor in the rear wheel hub and battery attached to the bottle holder inside the front triangle of the frame.

Surely weak forks are only an issue when using a front wheel hub motor?

I haven't read anything about potential frame robustness issues with rear wheel motors (at least not with 500W motors).

---

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