Which Donor Bike to start with?

[Klang180]

Hello Pedelecians (that will definitely catch on :S)

I have been thinking about making my own e-bike for a long time now. I don't want to go through the pre-made route partly because I like the idea of converting my own and two the power limits are too restrictive for what I want. I would like to go with a rear hub motor (but could be persuaded) of around 1000w.

I am however having a bit of a dilemma deciding what bike to build this conversion on maybe because I am not entirely sure of it's purpose. That aside though I wanted to get your opinions on the following three options which i think I have narrowed it down to.

1. A modern cheap(ish) MTB like a Giant Talon 3 or Trek Marlon 5. This will have modern MTB geometry 29 or 27.5 tyres and will enable me to go off road BUT will definitely be slower overall on road. I also worry that the aluminium frame will be too weak to take a rear hub motor? Is this correct?
2. A retro steel framed MTB like an Orange P7. This would have the old style geometry I am used to (currently ride a 99 GT Arrowhead) and would have a bullet proof steel frame but I wonder if all the other components like the forks will be up to a 1000w conversion?
3. A modern Hybrid like a Trek 7.5 or Specialized Sirrus. This would be the fatest on road option but limit me when it comes to off-road, something I am semi keen to do. Is this type of bike strong enough for 1000w hub motor through the rear?

I realise that a hub motor will change the feel of any bike significantly and make a MTB handle very differently but I accept that and would be using the bike just as much (if not more) on road. I also want to fit a rear rack so that I could use it for shopping etc. and this is half the reason I am justifying it at this stage.

So could I bother you to let me know which of the 3 above options you would choose and if I have missed anything at all?

Thanks so much for your time, if you need any further details let me know.

Gaz

 

[vfr400]

If you're going to go with one of those big heavy cheap direct drive motor kits, don't waste your money on any bike that costs more than £50. Look for one of those cheap catalogue bikes, ideally with a steel triangular frame and disc brakes. Buy it used. you can find them in second-hand shops, Ebay, Facebook ads, Gumtree, etc.

When you've installed the kit and ridden the bike, my recommendation will make a lot more sense to you.

Don't get a front motor because you'll hate it.

It might be an idea to tell us what you want to do with the bike so that we can give you other ideas on how to reach your ebiking nirvana.

 

[Klang180]

If you're going to go with one of those big heavy cheap direct drive motor kits, don't waste your money on any bike that costs more than £50. Look for one of those cheap catalogue bikes, ideally with a steel triangular frame and disc brakes. Buy it used. you can find them in second-hand shops, Ebay, Facebook ads, Gumtree, etc.

When you've installed the kit and ridden the bike, my recommendation will make a lot more sense to you.

Don't get a front motor because you'll hate it.

It might be an idea to tell us what you want to do with the bike so that we can give you other ideas on how to reach your ebiking nirvana.

Hello VFR400

Thanks for your reply. I'll admit i was going to go with that option as I don't have lots of money to spend but it seems that you may be saying that if you don't have the money to spend then perhaps it isn't a route worth taking?

I will definitely not get a front hub motor, I am sure of that.

As to what i want to do with ti. I suppose I really want it to replace my car in certain situations such as going to the shops to get food (hence the rack and panniers) and for getting to work but not getting there all sweaty. I know that a pre-built bike will do this with a 250w motor but I also want it to be fast and fun and a limit of 15.5mph doesn't cut it for me. I also started to fantasise that it might be fun to do a spot of zipping around some light off-road i.e. the type of stuff that would be borderline for a hybrid. Not full on MTB trails, just being able to go where a car can't without having to get off at every kerb etc. (No i am not going to be riding pavements, I just mean when there is an obstacle).

I have come to this forum to get an honest opinion so I do appreciate any feedback I get even if it is basically "don't do it". I don't want to invest time and money in a project that turns out was never really going to be properly realised anyway. What is the realistic minimum spend for a bike that will do the above, go over 15mph for at least 25-30miles and last more than a couple of months? I may as well ask now!

Thanks

 

[Raboa]

I would look at this police auction site to see if any of them suit.

Bumblebee Auctions

 

[Woosh]

if you want to go up in power, you need to scale up your budget to keep to the same level of comfort and performance.
Hanging an unspung 7kg weight on a 14kg bike will make handling awkward compared to a 3kgs-4kg crank drive motor.
On top of the motor weight, more power requires a bigger and heavier battery.

 

[KirstinS]

A 500w bbs mid drive seems like a good solution for what you want.

You can easily play about with settings for assistance above 15mph

Depending on the gearing ratios you can climb a vertical cliff or get some serious speed

Choose some crossover tires. I like schwalbe smart Sam's. They have a smooth central tread and knobblier outers.

I can do 40 miles all over the south downs or simply commute to work on the cycle paths.

 

[vfr400]

Those direct drive kits are cheap, but they're not very good. Don't get me wrong. I'm not an ebike snob. I'm just trying to make you aware of what they're like.

Many people want to go fast. I've built 45 mph ebikes and ones with over 6KW of power. I'm a motorcyclist, so used to going very fast on two wheels. These are my thoughts based on my experience. A bicycle is OK up to about 24 mph, though 20mph makes a good modal speed. When you go faster than that, you get various problems. Firstly, the car and other drivers can't conceive of a bike going that fast. Their experience tells them that bikes are slow, so they treat you as if you're going slow, like overtaking and cutting in just before a junction, roundabout, etc; pulling out from side roads right in front of you; etc. This means that you have to concentrate very hard - much more than when on a normal bicycle or motorbike. Secondly, tyres and brakes are insufficient to maintain traction. It's fine when you're on a straight road doing 30 mph until that car pulls out in front of you or cuts you up. After some time, it all just becomes too tedious and you'll be thinking about other solutions. I can tell you that riding a 30 mph bicycle is nothing like riding a normal bicycle at 30 mph.

Then you have the problem of police cars. Every time you see one, you'll be wondering whether they'll notice your massive pancake motor, which is clearly illegal. It's almost certain that they won't notice, but your guilt will always make you worry.

Those motors are unbelievably heavy. They draw a lot of power and so you need a powerful (heavy) battery to go with them. Your bike will no longer be comfortable to pedal without power from the motor. Basically, you convert a bicycle into an electric motorcycle that has insufficient brakes and tyres to deal with its momentum.

The cheapest kits have pedal sensors included, but the controllers only have one setting, which is maximum power when you pedal, which in most cases is not what you want, so you can forget about fitting the pedal sensor and use just the throttle instead, which sounds great if you come from motorcycling, but it's not the same on a bicycle and is not easy to control the power how you want it. The more expensive kits have LCDs with the controller. They're much better because they have 5 power levels for the pedal assist.

Although the kits are cheap, you need an expensive battery to power them. You can use a cheap battery, but it won't last long.

Range is very poor. You can get about 10 miles per 10Ah of battery provided that you don't use full power very often.

The rear motors don't have splines for cassette gears, so if you have a decent bike, you have to downgrade to freewheel gears, which means a maximum of 7 speeds or probably 5 speeds. that will probably mean that you need new shifters and derailleur. that's one of the reasons that I recommend fitting these kits to cheap bikes.

A front motor should only be fitted in steel rigid forks because aluminium drop-outs are not strong enough on their own. You have to add double torque arms, which is more expense and involves more complication for the installation.

If you fit one of these kits to a decent bike, you'll completely negate all the good things in that bike that you paid for. Why would you want nice light-weight wheels, frame etc., when you've just added 12kg to the bike? Everything that makes a decent bike good becomes completely irrelevant when you fit those kits.

Now that I've said all that, those kits can still be a suitable option, but only if it meets your needs. I know some people that have them and are happy, but none of them ride around at 30 mph. If you want to go ahead with the project, use a cheap donor bike, use good grip tyres that are at least 2" wide, get a decent battery, fit good quality hydraulic brakes and don't use it in stop-start traffic.

 

[vfr400]

I have come to this forum to get an honest opinion so I do appreciate any feedback I get even if it is basically "don't do it". I don't want to invest time and money in a project that turns out was never really going to be properly realised anyway. What is the realistic minimum spend for a bike that will do the above, go over 15mph for at least 25-30miles and last more than a couple of months? I may as well ask now!

If you're thinking about a 20 mph cruising speed, I'd say £550 to £600 for a Yosepower cassette motor kit and decent battery. You need a 48v kit and I think Yose Power always seem to have stock problems with them. To source the same stuff from alternative (Chinese) suppliers will cost maybe £750. The 36v Yose Power kits are good for cruising at something like 18 mph unless you pedal hard.

 

[Klang180]

A 500w bbs mid drive seems like a good solution for what you want.

You can easily play about with settings for assistance above 15mph

Depending on the gearing ratios you can climb a vertical cliff or get some serious speed

Choose some crossover tires. I like schwalbe smart Sam's. They have a smooth central tread and knobblier outers.

I can do 40 miles all over the south downs or simply commute to work on the cycle paths.

Hello Kirsten

That could be a good option and one i may explore. I am torn at the moment between making a good bike that'll last or just making a fast first time bike but i will look into the mid drive.

 

[Klang180]

Those direct drive kits are cheap, but they're not very good. Don't get me wrong. I'm not an ebike snob. I'm just trying to make you aware of what they're like.

Many people want to go fast. I've built 45 mph ebikes and ones with over 6KW of power. I'm a motorcyclist, so used to going very fast on two wheels. These are my thoughts based on my experience. A bicycle is OK up to about 24 mph, though 20mph makes a good modal speed. When you go faster than that, you get various problems. Firstly, the car and other drivers can't conceive of a bike going that fast. Their experience tells them that bikes are slow, so they treat you as if you're going slow, like overtaking and cutting in just before a junction, roundabout, etc; pulling out from side roads right in front of you; etc. This means that you have to concentrate very hard - much more than when on a normal bicycle or motorbike. Secondly, tyres and brakes are insufficient to maintain traction. It's fine when you're on a straight road doing 30 mph until that car pulls out in front of you or cuts you up. After some time, it all just becomes too tedious and you'll be thinking about other solutions. I can tell you that riding a 30 mph bicycle is nothing like riding a normal bicycle at 30 mph.

Then you have the problem of police cars. Every time you see one, you'll be wondering whether they'll notice your massive pancake motor, which is clearly illegal. It's almost certain that they won't notice, but your guilt will always make you worry.

Those motors are unbelievably heavy. They draw a lot of power and so you need a powerful (heavy) battery to go with them. Your bike will no longer be comfortable to pedal without power from the motor. Basically, you convert a bicycle into an electric motorcycle that has insufficient brakes and tyres to deal with its momentum.

The cheapest kits have pedal sensors included, but the controllers only have one setting, which is maximum power when you pedal, which in most cases is not what you want, so you can forget about fitting the pedal sensor and use just the throttle instead, which sounds great if you come from motorcycling, but it's not the same on a bicycle and is not easy to control the power how you want it. The more expensive kits have LCDs with the controller. They're much better because they have 5 power levels for the pedal assist.

Although the kits are cheap, you need an expensive battery to power them. You can use a cheap battery, but it won't last long.

Range is very poor. You can get about 10 miles per 10Ah of battery provided that you don't use full power very often.

The rear motors don't have splines for cassette gears, so if you have a decent bike, you have to downgrade to freewheel gears, which means a maximum of 7 speeds or probably 5 speeds. that will probably mean that you need new shifters and derailleur. that's one of the reasons that I recommend fitting these kits to cheap bikes.

A front motor should only be fitted in steel rigid forks because aluminium drop-outs are not strong enough on their own. You have to add double torque arms, which is more expense and involves more complication for the installation.

If you fit one of these kits to a decent bike, you'll completely negate all the good things in that bike that you paid for. Why would you want nice light-weight wheels, frame etc., when you've just added 12kg to the bike? Everything that makes a decent bike good becomes completely irrelevant when you fit those kits.

Now that I've said all that, those kits can still be a suitable option, but only if it meets your needs. I know some people that have them and are happy, but none of them ride around at 30 mph. If you want to go ahead with the project, use a cheap donor bike, use good grip tyres that are at least 2" wide, get a decent battery, fit good quality hydraulic brakes and don't use it in stop-start traffic.

Hey VFR

Thanks for this thorough and well thought through response. I can see that maybe it isn't the right option for me to go down the cheap route. My only remaining idea on this front would be to potentially get a cheap motor to get me started but then invest in a decent battery from the off. Ok this means I will be paying a lot more but presumably the battery can then be swapped to another bike and I can upgrade the motor (and probably bike too). I have an old mountain bike i could use but even if i got a newer bike i would never buy new as it just doesn't get you good value.

The points you make about riding on the road are all really good points and something I hadn't actually fully appreciated. I mean i am very expereinced at riding bikes and have some scooter experience but take your point about the weight of these bikes and the feeling of worrying about th police and other drivers. Even now i find that drivers are desperate to get around me even if i am already going 20mph so wouldn't envisage doing any more than that on road. It was really more to enable me to go to work on a quieter but hillier route and not get there dripping. I also liked the idea of a few thrashes around gentle off road but I guess with a much changed feel to the bike it might not be all that fun.

Really starting to feel I might go the mid drive route but with that I am worried about limits and the wear on the components as I've heard it is very tough on chains and the drivetrain in general.

More research is required obviously, thanks to all.

 

[Klang180]

Hey VRF, are these hub kits for example any good?

48V350W E-bike Hub Motor Conversion kit Electric Bike Kit Rear Wheel 26" Black | eBay

Find many great new & used options and get the best deals for 48V350W E-bike Hub Motor Conversion kit Electric Bike Kit Rear Wheel 26" Black at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

BAFANG 48V 500W Rear Hub Motor Cassette Freewheel Conversion Kit For DIY Ebike | eBay

Find many great new & used options and get the best deals for BAFANG 48V 500W Rear Hub Motor Cassette Freewheel Conversion Kit For DIY Ebike at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

 

[sjpt]

It was really more to enable me to go to work on a quieter but hillier route and not get there dripping.

A conventional (legal) 250w kit (front, mid or rear) will do that. They can actually generate much more on hills than the nominal power, which is a continuous power.

 

[vfr400]

Hey VRF, are these hub kits for example any good?

48V350W E-bike Hub Motor Conversion kit Electric Bike Kit Rear Wheel 26" Black | eBay

Find many great new & used options and get the best deals for 48V350W E-bike Hub Motor Conversion kit Electric Bike Kit Rear Wheel 26" Black at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

BAFANG 48V 500W Rear Hub Motor Cassette Freewheel Conversion Kit For DIY Ebike | eBay

Find many great new & used options and get the best deals for BAFANG 48V 500W Rear Hub Motor Cassette Freewheel Conversion Kit For DIY Ebike at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

Both those kits are good. The first one is Yose Power that I mentioned, but it's the freewheel version. That normally means 7 speeds max, so you have to do something with your shifter. If you any more speeds than that on the donor bike. The Bafang kit will be plug and play. I'm not so familiar with that controller, but Bafang stuff is normally pretty good.

Don't get too hung up on the power stated in the listing. All motors in that size range give about the same power. it's the controller that decides how much power you get, which is related to battery volts times the current written on the controller.

Also, the top speed doesn't depend on power. It depends on how the motor is wound. You can have a low power motor that spins very fast or a high powered motor that won't get you past 15 mph. The Yose Power kit is around 260 rpm,which will give you a 20mph cruising speed. The Bafang kit says 470 rpm. I don't believe that. If it is that speed, it's not suitable. It'll overheat and be very inefficient. The picture shows a label with 20" written on it and they mention 40 km/h, which would be about right for a 470 rpm 20" wheel. You need to ask them the rpm or speed of the motors for the bigger wheels and pray that they know what they're talking about. Most of these suppliers don't have a clue about these things, so be careful.

Nothing is simple, is it?

 

[Klang180]

Both those kits are good. The first one is Yose Power that I mentioned, but it's the freewheel version. That normally means 7 speeds max, so you have to do something with your shifter. If you any more speeds than that on the donor bike. The Bafang kit will be plug and play. I'm not so familiar with that controller, but Bafang stuff is normally pretty good.

Don't get too hung up on the power stated in the listing. All motors in that size range give about the same power. it's the controller that decides how much power you get, which is related to battery volts times the current written on the controller.

Also, the top speed doesn't depend on power. It depends on how the motor is wound. You can have a low power motor that spins very fast or a high powered motor that won't get you past 15 mph. The Yose Power kit is around 260 rpm,which will give you a 20mph cruising speed. The Bafang kit says 470 rpm. I don't believe that. If it is that speed, it's not suitable. It'll overheat and be very inefficient. The picture shows a label with 20" written on it and they mention 40 km/h, which would be about right for a 470 rpm 20" wheel. You need to ask them the rpm or speed of the motors for the bigger wheels and pray that they know what they're talking about. Most of these suppliers don't have a clue about these things, so be careful.

Nothing is simple, is it?

Thanks that is very interesting. I was thinking watts means speed and hadn't considered the speed aspect, I will do now though. 20mph sounds decent so may consider that one, thanks for all of your input it has been invaluable and certiabnly got me closer to a decision.

 

[Ten98]

The yosepower 350W rear wheel kit was what I got, I shoved it on a bog standard Halfords "hybrid" bike that I got for £200 and I'm absolutely loving it! The motor is tiny, you can barely notice it's there.
I tried someone else's front wheel kit and it was awful, like a skittering hamster and not good through the front shocks on the bike. Definitely worth the extra effort to put it on the rear wheel, it's like it pushes you up hills from behind.

20mph is plenty as others have said any faster than that and you risk both motorists not anticipating your speed and also the police inspecting your potentially not street-legal bike.

 

[Jayfdee]

I originally converted an old Orange P7 with a rear hub cheapie, it is very heavy,repairing a puncture is a pain, and as others have noted it is hungry with th battery.
My second build was on a new Giant ATX with a Bafang crank drive,it is way way better.
My recommendation is the crank drive route on a cheap new bike,it does twice the mileage on the same battery,handles well, is light enough to lift over obstacles.
I went for 250W and upped the controller to 18amps,done over 1000 trouble free miles.
Good luck with whatever you choose.

 

[Nealh]

I originally converted an old Orange P7 with a rear hub cheapie, it is very heavy,repairing a puncture is a pain, and as others have noted it is hungry with th battery.
My second build was on a new Giant ATX with a Bafang crank drive,it is way way better.
My recommendation is the crank drive route on a cheap new bike,it does twice the mileage on the same battery,handles well, is light enough to lift over obstacles.
I went for 250W and upped the controller to 18amps,done over 1000 trouble free miles.
Good luck with whatever you choose.

It sounds like you are comparing chalk vs cheese.
The cheap hub probably is a 1000w D/D hub (it is very heavy is a clue and gives the game away) inefficient compared to a lighter geared hub (about 3 - 3.5kg ).
Comparing a D/D with a mid drive BBS 250w is no comparison so it will prove to have better range.
For most riding a good geared hub I find is a match for a mid drive and far more reliable.

Again not what is better a mid drive or hub but just from personal experience I prefer a hub all day long, others will always prefer a mid drive it is purely down to preference. To make a valid comparison products need to be similar, a geared hub and mid drive are a lot more closely matched then a D/D motor comparison.

 

[vfr400]

IMHO, hub motors are way better than crank motors for commuting and general travelling. A crank-drive has some advantages in some situations, like very steep long hills or serious off-road use. I can generalise by saying that hub-motors are more reliable, quieter, cheaper and more user-friendly than a crank-motor. Hub-motors also reduce the load on the entire drive system, while a crank-drive multiplies it significantly. That also has an effect on running costs and overall reliability of the bike.

The crank motor has the advantage of being able to deliver its power at whatever speed you want, so you can go slow one day and fast the next, while as a hub-motor needs to be chosen to run with best power and efficiency at your modal speed.

 

[Klang180]

The yosepower 350W rear wheel kit was what I got, I shoved it on a bog standard Halfords "hybrid" bike that I got for £200 and I'm absolutely loving it! The motor is tiny, you can barely notice it's there.
I tried someone else's front wheel kit and it was awful, like a skittering hamster and not good through the front shocks on the bike. Definitely worth the extra effort to put it on the rear wheel, it's like it pushes you up hills from behind.

20mph is plenty as others have said any faster than that and you risk both motorists not anticipating your speed and also the police inspecting your potentially not street-legal bike.

Thanks for this, very interesting indeed. It seems that maybe I will go for that one in that case as I don't really need anything over 20mph and it will give me the ability to use a bike where i might have previously only thought about using a car i.e. trip to a shop with a load. It also makes the whole thing less of a daunting process as although going a couple of miles to the shops on a normal bike is no big deal sometimes you just cannot be bothered.

I think i will look into this kit as VFR and yourself both seem to rate a good quality rear hub over a mid drive, all things considered of course.

Thanks so much to all of you. If nothing else I know to stay well clear of those DD hubs!

 

[Klang180]

I originally converted an old Orange P7 with a rear hub cheapie, it is very heavy,repairing a puncture is a pain, and as others have noted it is hungry with th battery.
My second build was on a new Giant ATX with a Bafang crank drive,it is way way better.
My recommendation is the crank drive route on a cheap new bike,it does twice the mileage on the same battery,handles well, is light enough to lift over obstacles.
I went for 250W and upped the controller to 18amps,done over 1000 trouble free miles.
Good luck with whatever you choose.

I appreciate your take on this and will bear this in mind but I think that a good quality geared hub may be the best for my budget and circumstances. Knowing me though this won;t be my last bike and I will soon be "investing" time and money into another project in which case a mid drive will most likely be my preferred option!