Help! Looking for a lightweight and compact conversion kit

[Katrina]

I've got a Trek Domane AL2 that I usually ride around town.

Lately, I've been joining my friends on some trail rides, but mansome of these hills are brutal. I'm finding it tough to keep up on the steeper stretches.

I'm thinking about getting an e-bike conversion kit to give me a bit of a boost, especially since I don't need something with huge torque or a long range. I'm looking for something lightweight and compact—nothing too bulky.

Any recommendations would be great! Thanks a ton!!!

 

[Benjahmin]

Have a look at Topbikekit. Assemble your own kit from all the components, help available here. Battery can be UK sourced from Greenlance.
Woosh will supply complete plug and play kits.
You need to zone in on what you need. Hub(front or rear) or mid drive. Battery size dependant on your range requirments and terrain type.

 

[Peter.Bridge]

Generally mid drive conversions are stronger up off road steep hills, but tend to be heavier conversions. Hub drives are surprisingly capable, depending how steep the hill is, rider weight and how much pedalling effort the rider puts in. Is it "light" off roading or real mountain bike off roading ? Is there an example route we could check the maximum gradient

ETA : just looked up the domane AL2, looks like a very light bike, possibly use a lightweight hub coupled with a bag battery, maybe a Bafang G370 or Aikema AKM-75 or @Woosh are getting in a lightweight hub with built in torque sensor tongsheng 85ts

Help! - Converting folder bike to cassette

There seems quite a lot of 7 speed freewheel folding bikes with disc brakes (e.g. https://www.compass24.com/compass-folding-bike-20-inch-blue-415370/blue) which seems to get good reviews on bike forums. If I added a hub motor,.my only concern would be the smallest freewheel cog is 14t. If I...

www.pedelecs.co.uk

 

[saneagle]

Surely, if you want to go trail riding, an MTB would be better? Just buy the cheapest one you can find as long as it has disc brakes and a triangle frame. Ideally, it should have 26" wheels and 7- speed gears. When you have a motor of any sort, you don't need fancy gears or anything like that. With such a bike, you can fit a nice powerful but light Q100H/AKM100 rear freewheel motor. 15A KT controller and 48v downtube battery to get a reliable, durable and enjoyable ebiking experience. The whole lot should cost around £600. Keep your road bike for exercise.

 

[Katrina]

Have a look at Topbikekit. Assemble your own kit from all the components, help available here. Battery can be UK sourced from Greenlance.
Woosh will supply complete plug and play kits.
You need to zone in on what you need. Hub(front or rear) or mid drive. Battery size dependant on your range requirments and terrain type.

Thanks!!
I've done a bit of research, and I think a rear hub motor is the way to go for me. I'm worried about the handling with a front hub motor
For battery size, something like the Swytch bike air (7-10 miles) seems to meet my needs. I just want power on the uphills, but from what I've seen, most of the batteries on the market are just too big and heavy

 

[Katrina]

Generally mid drive conversions are stronger up off road steep hills, but tend to be heavier conversions. Hub drives are surprisingly capable, depending how steep the hill is, rider weight and how much pedalling effort the rider puts in. Is it "light" off roading or real mountain bike off roading ? Is there an example route we could check the maximum gradient

ETA : just looked up the domane AL2, looks like a very light bike, possibly use a lightweight hub coupled with a bag battery, maybe a Bafang G370 or Aikema AKM-75 or @Woosh are getting in a lightweight hub with built in torque sensor tongsheng 85ts

Help! - Converting folder bike to cassette

There seems quite a lot of 7 speed freewheel folding bikes with disc brakes (e.g. https://www.compass24.com/compass-folding-bike-20-inch-blue-415370/blue) which seems to get good reviews on bike forums. If I added a hub motor,.my only concern would be the smallest freewheel cog is 14t. If I...

www.pedelecs.co.uk

You're right! I think a hub motor could be just what I need. I mostly do "light" off roading, and the maximum gradient is around 20%.

Thanks for the suggestions tailored to my bike! You really seem to have a grasp on the lightweight options. I'm going to check out the products you suggested!

 

[Katrina]

Surely, if you want to go trail riding, an MTB would be better? Just buy the cheapest one you can find as long as it has disc brakes and a triangle frame. Ideally, it should have 26" wheels and 7- speed gears. When you have a motor of any sort, you don't need fancy gears or anything like that. With such a bike, you can fit a nice powerful but light Q100H/AKM100 rear freewheel motor. 15A KT controller and 48v downtube battery to get a reliable, durable and enjoyable ebiking experience. The whole lot should cost around £600. Keep your road bike for exercise.

Thanks for the detailed recommendations! I might consider getting an MTB or a gravel bike in the future, haha. For now, I'd like to stick with modifying my road bike because I still want to keep that speed on the flats.

 

[Peter.Bridge]

You're right! I think a hub motor could be just what I need. I mostly do "light" off roading, and the maximum gradient is around 20%.

Thanks for the suggestions tailored to my bike! You really seem to have a grasp on the lightweight options. I'm going to check out the products you suggested!

20% gradient is quite steep for a small hub motor, unless you are very light and providing quite a lot of pedalling input. The problem is that at very low speeds the motor is inefficient and won't provide as much assistance (and the controller will eventually overheat if that sort of gradient is sustained). That said, some of the hills marked as 20% are only that gradient for a short distance. I (105kg) cycle up one marked as 17% on my folding bike with a front hub (1.44 kg akm-75) and it's fine, but that is only around 100 feet of climbing. Make sure you get a motor that has a lower maximum speed if you want it primarily for hills (201 rpm for 700c wheels)

Woosh do battery bags which are light, I think the 36v 10Ah one is 1.8 kg

Let us know how you get on with your project - I'm really interested.

Here is a motor simulator for the very light Bafang hub (g370) going up a 20% hill, I have assumed you can generate 200 watts of pedalling power up the hill ! You also need to set the weight of bike and rider.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

It would overheat after 3.5 minutes

 

[Peter.Bridge]

Thanks!!
I've done a bit of research, and I think a rear hub motor is the way to go for me. I'm worried about the handling with a front hub motor:

I have done a couple of front hub conversions, but only on folding bikes. @Nealh uses a front hub G370 and has been very happy with it. I think the handling with a very light hub motor (eg 1.44kg akm-75) is very different to a heavier motor, and also will depend on the bike geometry and forks.

 

[Katrina]

OMG, you really know the stuff! You're absolutely right, for small hub motors, weight and pedal input are crucial for those long, steep climbs.
So, I'm curious, does the akm-75 do the trick for you? And that 1.44kg is super tempting!

 

[Peter.Bridge]

OMG, you really know the stuff! You're absolutely right, for small hub motors, weight and pedal input are crucial for those long, steep climbs.
So, I'm curious, does the akm-75 do the trick for you? And that 1.44kg is super tempting!

Well, there's people here a lot more experienced than me : @Nealh , @saneagle , @Bonzo Banana, @Woosh to name but 4. My experience is a 328 rpm akm-75 front hub motor in a 20" wheel folding bike. I didn't notice any difference in handling and even with the motor switched off I can cycle a 9 mile test circuit in nearly identical time in the converted bike without any motor assistance.

I am a little wary about putting a front hub motor on a lightweight road bike, but I think you would have to try it and see. Possibly get the motor with road bike rims ? - I would use a 201 rpm (for hill climbing) akm-75 front hub and a woosh bag battery. How heavy are you ?

 

[Katrina]

I have done a couple of front hub conversions, but only on folding bikes. @Nealh uses a front hub G370 and has been very happy with it. I think the handling with a very light hub motor (eg 1.44kg akm-75) is very different to a heavier motor, and also will depend on the bike geometry and forks.

I've been doing some digging. For a road bike, it seems like a rear hub motor might be the better fit...
I think the akm-75 you mentioned sounds pretty perfect for me! But it looks like it doesn't support the thru-axle

 

[Katrina]

Well, there's people here a lot more experienced than me : @Nealh , @saneagle , @Bonzo Banana, @Woosh to name but 4. My experience is a 328 rpm akm-75 front hub motor in a 20" wheel folding bike. I didn't notice any difference in handling and even with the motor switched off I can cycle a 9 mile test circuit in nearly identical time in the converted bike without any motor assistance.

I am a little wary about putting a front hub motor on a lightweight road bike, but I think you would have to try it and see. Possibly get the motor with road bike rims ? - I would use a 201 rpm (for hill climbing) akm-75 front hub and a woosh bag battery. How heavy are you ?

I weigh 60 kg.

 

[saneagle]

A rear motor would be better. Front motors lose traction on steep hills because all the weight goes onto the rear wheel. On grass or gravel or any other lose surface, the wheel will spin when you need the help the most. On the road, it's not too bad. Q100C is pretty light at 2.2kg. It's quite wide, but I've always managed to fit them OK; however, you'll probably need to dish the wheel a fair amount to get the rim central because the centre of the hub is offset to the left.

 

[Woosh]

But it looks like it doesn't support the thru-axle

The rear axle version (85TTS) is a very new product and is not in full production yet.
I will get samples for testing next month but won't have products for sale until March.
Please note that the normal version (85TS) has OLD of 135mm, the 85TTS has OLD of 142mm and also slightly heavier (1.9kgs instead of 1.6Kgs). The maximum torque remains the same, 35NM, perfect for 20" folding bikes.

 

[Katrina]

A rear motor would be better. Front motors lose traction on steep hills because all the weight goes onto the rear wheel. On grass or gravel or any other lose surface, the wheel will spin when you need the help the most. On the road, it's not too bad. Q100C is pretty light at 2.2kg. It's quite wide, but I've always managed to fit them OK; however, you'll probably need to dish the wheel a fair amount to get the rim central because the centre of the hub is offset to the left.

This one?
Do you hand-build the bike wheels yourself? Wheel building is quite a complex process!

 

[Katrina]

The rear axle version (85TTS) is a very new product and is not in full production yet.
I will get samples for testing next month but won't have products for sale until March.
Please note that the normal version (85TS) has OLD of 135mm, the 85TTS has OLD of 142mm and also slightly heavier (1.9kgs instead of 1.6Kgs). The maximum torque remains the same, 35NM, perfect for 20" folding bikes.

Wow! Will the OLD of 142mm also fit 20" folding bikes?

 

[Woosh]

Wow! Will the OLD of 142mm also fit 20" folding bikes?

The 135mm dropout is most popular. Still, It's possible to fit a motor with142mm dropout into a bike with a 135mm dropout. The solution depends on the donor bike.

 

[Katrina]

I've really learned a lot! Thank you very much!!

 

[saneagle]

Wow! Will the OLD of 142mm also fit 20" folding bikes?

I fitted one to a Dahon Jetstream 8, which has quite a stiff rear subframe. As I said, you have to dish the wheel quite a lot, which is why I'd recommend the freewheel version and 7-speed gears. 7-speed gears are very cheap if you want to change from anything higher.