£900 for conversion, can I do cheaper and or more powerful?

[zilali]

I recently bought a bike from a local shop which I really love, it's comfy and a joy to ride. see https://www.bristolbicycles.co.uk/product/hybrid-bike/
So the same company also makes e-bikes. https://www.bristolbicycles.co.uk/product/e-city/
After a recent illness and sharp decline in energy levels, I'm looking to convert my current bike to an e-bike. The company says they can convert my bike to the above e-bike for 900 pounds. It looks like the specs are ...

Motor: Bafang 43v 250W geared rear hub motor, 45Nm torque
Battery: 450Wh, 43v rear rack battery pack containing Samsung lithium-ion cells. 2-year warranty.

My question is, is this good value? If I were to do the same myself could I potentially make a bike that goes further and faster for the same price (n.b I'm willing to break the laws a little)? Or just as good but for much cheaper? The bike they have does look very clean in it's wiring (e.g. can't even see a controler) and I wonder if I could achieve that at home.
I have very little mechanical experience so don't want to do anything too complex, but I am willing to get my hands a little dirty.

What do you guys think? Thanks!

 

[vfr400]

43v is a strange voltage. I guess that it's a 12S battery, so the motor gets about 20% more torque than it would with a 10S (36v) one. The motor speed isn't indicated. You'd have to have a look at one and see what code number is on it to get an idea of the speed.

I think the price for the kit and fitting it isn't bad, but I have some reservation. I'd like to see the control system. is it a crappy LED control panel or an LCD one, and which type? That can make a big difference to how nice the bike rides. Also, with a rear motor, I'd want a battery in the triangle to balance the bike better.

A nice 48v battery can be had for about £350, a nice controller is about £70 and a motor wheel is about £200 -£250. By the time you've bought ancillary items, you'll be up to £700, but it'll be a lot better kit at the expense of having to figure out how to connect it up, soldering a few connectors and things like that. You can buy ready-made kits from places like Woosh, though I don't know the prices. It depends what you want.

Make a list of your performance requirements, then we can make more specific recommendations.

 

[Nealh]

As you are in Brizzy pop in to Revolution works (BS4 1ET) to test out their Friction drive kit bike it may or may not surprise you.

 

[zilali]

Thanks for the replies guys...
So my performance requirements are...

• Probably 250W power (would be nice to have potential to upgrade to 500W if i find it's too low without buying a whole new kit)
• Won't be tackling too many hills, mostly flat.
• Longer distance massive advantage but for now 30ish miles on the flat would be great.
• Would be great to get power when cycling faster than 15mph limit on most e-bikes
• Would prefer not to be too DIY looking (e.g. controller in a saddle bag), nor anything too easily nick-able when I lock it up
• Relatively easy to install (so I guess this excludes mid-motors)
• Not too heavy would be nice too.

If you have any specific kit recommendations that would be great. Thanks
I will also check out Revolution works but I"m afraid distance might be a bit too low.

 

[Nealh]

Above 15.5mph e bikes will use more battery energy as you are then in to wind resistance territory even on a calm day.

 

[zilali]

Ah ok, well above 15.5mph would be a nice to have but not essential. Typically does going from 250W to 500W add a lot of weight to a kit?

 

[Woosh]

You need to understand nominal power and construction power.
Nominal power is printed on the label, usually 250W.
Construction power is what the manufacturers will guarantee that should you use that motor continuously at their maximum rating, it will perform continuously.
When you talk about construction power, 250W motors are usually geared hub motors with 120mm diameter, giving about 45NM maximum torque.
350W motors are usually larger geared hub motors with 140mm diameter, 55NM maximum torque.
500W motors are even larger geared hub motors with 160mm diameter, 65NM maximum torque.
Above 500W, they are usually even larger direct drive motors.
For crank drives, 250W motors give about 80NM at the chainring, 350W give 100NM at the ring, 500W give 120NM at the ring.

You may want to know why manufacturers can fit a motor built for 500W construction power to a bike and specify it as 250W nominal. The answer is you don't need more than 200W to hold on to 15mph. Same situation when you have a car with 5L engine and drive around in a 20mph zone.

Typically does going from 250W to 500W add a lot of weight to a kit?

No, about 1kg.

 

[zilali]

You need to understand nominal power and construction power.
Nominal power is printed on the label, usually 250W.
Construction power is what the manufacturers will guarantee that should you use that motor continuously at their maximum rating, it will perform continuously....

No, about 1kg.

Thanks for the detailed reply, so would you recommend any kits in the 250W to 500W range?

 

[Woosh]

no. There is really no need to buy an illegal kit.
Define which characteristics you need (maximum torque, cassette for freewheel, weight, budget, optimised speed) - members will advise you which components you'll need and why.

 

[zilali]

Hi, so charateristics would be...

Maximum torque: I couldn't say, but if it helps I just rode a Raleigh Array prebuilt and the toque was good enough. I'll be riding up a few hills but not excessively so.

Cassette for freewheel: 8 speed

Budget: I have 1000 pounds but would like to spend a lot less than that. I'd be happy spending 700ish, even happier spending less.

Optimised speed: Not exactly sure what you mean by this.

 

[Woosh]

the Array has 45NM Suntour motor, 11AH battery (400WH), torque sensor.
The equivalent is my TS kit XF08C with 13AH battery.
It will cost you £529.
You can have a bigger battery capacity if you like, the same kit with 17AH costs £629.
https://wooshbikes.co.uk/cart/#/product/uid-223-xf08c-ts13ah/xf08c-ts-rear-hub-kit-26700c-with-13ah-battery

If you want a throttle, you'll need a cadence sensor kit. It's cheaper (£499 with 13AH) but does not give the same riding experience.
https://wooshbikes.co.uk/cart/#/product/uid-121-xf08c-13ah/xf08c-rear-hub-kit-with-13ah-battery
If you want more torque, the DWG22C kit will give you 40% more.
If you want lightweight, the Aikema 85SX will do that.

My kits are by no mean the only choices but that gives you an idea what you can get.

 

[Woosh]

Optimised speed: Not exactly sure what you mean by this.

this is where you like to cruise at. Typically 15mph.

 

[zilali]

thanks for the speedy reply, I will look into those

 

[zilali]

the Array has 45NM Suntour motor, 11AH battery (400WH), torque sensor.
The equivalent is my TS kit XF08C with 13AH battery.
It will cost you £529.
You can have a bigger battery capacity if you like, the same kit with 17AH costs £629.
https://wooshbikes.co.uk/cart/#/product/uid-223-xf08c-ts13ah/xf08c-ts-rear-hub-kit-26700c-with-13ah-battery

If you want a throttle, you'll need a cadence sensor kit. It's cheaper (£499 with 13AH) but does not give the same riding experience.
https://wooshbikes.co.uk/cart/#/product/uid-121-xf08c-13ah/xf08c-rear-hub-kit-with-13ah-battery
If you want more torque, the DWG22C kit will give you 40% more.
If you want lightweight, the Aikema 85SX will do that.

My kits are by no mean the only choices but that gives you an idea what you can get.

So I'm interested in these kits but I'm wondering if it would be suitable for my bike as my current bike has 3 chainrings on the crank set (if that's the correct vocab), therefore would your geared hub motors not be better? Not exactly sure the benefits of getting a torque sensor kit.

The other thing I am wondering about is if the battery and other components are quite stealable when I say, lock it up in town? Prebuilt bikes seem to have a lock and key for the battery, is this an option?

Finally, if I get in a pickle putting it all together is it easy to find a bike shop to help? I spoke to one e-bike shop about kits but they said they wouldn't install them.

 

[sjpt]

Geared hub give less wear on the drivetrain and generally a little better for a commute and regular jaunts. Serious off road or big hills benefit from crank motor.

Torque sensors work by multiplying up the effort you put in; typically 50% on lowest assist (you put in 2/3 total, it puts in 1/3) up to 300% on highest assist (you put in 1/4, it puts in 3/4). Some give more on highest. This gives a very natural pedal experience, and on start the motor kicks in almost as soon as you put pressure on the pedals which is good for uphill start over a junction.

Cadence sensor just detects that you are pedalling, and the motor then gives effort based on your assist setting. One good thing there is ghost pedalling; as long as you turn the pedals the motor does its thing even with no effort from you. Helpful if you are tired at then end of a long ride, or have any disabilities that can lead to quick exhaustion. Hill starts can be a little awkward as you don't get any assist till around 1/2 turn of the pedals.

Almost all kits have lock and key for the battery. The battery remains locked all the time unless you remove it for charging (can charge inside or on bike).

Might not be that easy to get a bike shop to help, but people on this forum will. If you can do regular maintenance you can fit a kit.

 

[zilali]

If you want a throttle, you'll need a cadence sensor kit. It's cheaper (£499 with 13AH) but does not give the same riding experience.
https://wooshbikes.co.uk/cart/#/product/uid-121-xf08c-13ah/xf08c-rear-hub-kit-with-13ah-battery
If you want more torque, the DWG22C kit will give you 40% more.
If you want lightweight, the Aikema 85SX will do that.

My kits are by no mean the only choices but that gives you an idea what you can get.

Hi Whoosh, So I just took the e-city bike (top of thread) for a test ride and it was a lot of fun. I realised I would prefer to buy a candence sensor kit than a torque sensor kit, so it looks like the XF08C Rear Hub Kit would be best for me. A few questions though if you don't mind...

My frame is big enough for a downtube battery but only has 2 holes (instead of 3 required for the kit), would it be better to get a rear rack battery instead, or would attaching it via 2 holes suffice?

Is the 17ah battery significantly heavier than the 13ah battery? I couldn't find the watt hours of each of these on your site too.

I'm a bit confused about the role of the cassette, does this come with the kit or is it something I buy separately?

On your site it says your kits are out of stock yet they are still live on the online shop? Would the above kit be available to buy now?
Cheers

 

[Woosh]

My frame is big enough for a downtube battery but only has 2 holes (instead of 3 required for the kit), would it be better to get a rear rack battery instead, or would attaching it via 2 holes suffice?

no. If you have a crank drive kit, then yes, you can drill a hole through the aluminium battery base and 2 holes would have suffice. If you have a hub kit, the controller is integrated into the aluminium base, so you can't drill through the aluminium base. You will have to drill into your downtube and fit the rivnuts (two are supplied with the kit). You will need a 6.5mm or 7mm drill bit but don't have to buy anything.
If you don't want to drill into the downtube, I will have the lighter G20 and G30 kits that don't need drilling end of August/beginning of September.

https://wooshbikes.co.uk/2020/battery/G20.jpg

https://wooshbikes.co.uk/2020/battery/G30.jpg

They are extremely lightweight, the G20 weighs only 1.3kgs, G30 1.8kgs. The G30 costs the same as the 13AH HL battery, the G20 costs £50 less.

Is the 17ah battery significantly heavier than the 13ah battery? I couldn't find the watt hours of each of these on your site too.

No. Both weighs roughly the same, 3.1kgs. The 13AH is made with Samsung cells, the 17AH with Panasonic cells.

I'm a bit confused about the role of the cassette, does this come with the kit or is it something I buy separately?

Look at the rear sprockets on your bike. If you have 8-speed or more or have a quick release, it's a cassette. Otherwise, freewheel.
Rear hub motors can have one of the two lids: one with thread for screw on freewheels and one with a freehub body for cassettes.
If you don't intend to re-use the old screw on freewheel or cassette, it does not matter, you just buy a new freewheel or cassette to suit your gears and motor. We tend to use motors with freewheels on our bikes because in years to come, the freehub mechanism may need replacing and you may have to send the motorwheel back to Southend for that. Whereas you can replace the freewheel yourself.

On your site it says your kits are out of stock yet they are still live on the online shop? Would the above kit be available to buy now?

We are currently out of stock until the next shipment arrives, ETA 03-August.
There is no deposit. I usually ask customers to give me enough information to either advice or interpret what is needed then pass on the information to Andy. He will check all the information we have, pictures of the bike, of the handlebars and bottom bracket are very much needed to avoid potential problems. He then ring you to confirm all the details like cable lengths before preparing your kit.
You only pay when the kit is ready to go.