Help - kit recommendations for Raleigh Twenty

[Bumtreq]

Hi All,

The current climate has me thinking about putting a motor on my little Twenty. See the photo link below. I suspect I'll be back at work in a couple of months (London) and want a bike for my daily commute. My flat to the office is approximately 3.5-4 miles each way, and it is quite flat. I'm a heavy rider, so I'm hoping for something with a bit more power. I have motorised five bikes in the past, but those were with 2 stroke motors when I was living in Australia. I'm very new to the world of electric bikes!

Any recommendations and suppliers would be greatly appreciated. I've seen a few kits floating around on Ali Express etc. but I'm not sure what the budget should be for this build. Looks like batteries are the killer!

http://imgur.com/a/2KU5oZv

Cheers
B

 

[Woosh]

Main problem is where you want the battery (36cm L x 10cm W x 10cm H).
If you can put it inside your Whiskey box, then the rest is easy.

 

[Bumtreq]

Hi Woosh,

More than happy for it to go in the Whiskey box, assuming it fits. I'd also be up for replacing the box if necessary. Would a front hub 20" kit be better than a crank positioned motor? Ideally trying to keep everything under £500.

Cheers

 

[Nealh]

d8veh/Vfr's old thread.

 

[Amoto65]

The current climate has me thinking about putting a motor on my little Twenty.

Hi, I have a Raleigh as well and have often thought of turning it into an electric bike, not sure about sorting the wheel size in a front hub motor with them being an odd size ie not a standard 20" (406) but (451) .

 

[Woosh]

Hi Woosh,

More than happy for it to go in the Whiskey box, assuming it fits. I'd also be up for replacing the box if necessary. Would a front hub 20" kit be better than a crank positioned motor? Ideally trying to keep everything under £500.

Cheers

A front hub motor will look nicer.
You need to check the dropout - measure the inside of the fork, between the two jaws. I hope it's standard 100mm.

 

[Nealh]

What ever motor/hub is used you will need to look for 300/328rpm to get the torque in a small wheel.

 

[Bumtreq]

Hi,
Would the smaller wheel not give it extra torque, therefore I’d be looking for higher rpm to gain top end? Maybe I’m misunderstanding something here.

Amoto65 is right, the wheel size will be off. Do they sell kits that include a 20” rim? Maybe that would be more suitable...

 

[Bumtreq]

Not too sure how wide the front is, but this is an image I found from when I first bought it. Unfortunately the bike is still at the office. I’ll walk to the office this weekend and cycle home with it.

 

[E-Pashley]

That takes me back - I remember snapping the frame on one of these while doing "wheelies" over a roundabout (40 something years ago)
The ground clearance is probably a bit low for a mid mount kit, and as already mentioned 20" seems to have changed size over the years. The front fork can probably be "tweaked" to 100mm .
In my opinion the best looking (but not the cheapest) option would be to have the front rim rebuilt onto an electric hub and hide the battery in that awesome rear box. Personally I'd find a different battery before I'd change that box - but that's just a personal opinion

BTW - smaller wheel = more torque - your pushing from the middle, not pulling from outside

 

[Bumtreq]

Sorry to bombard the thread, but would a mid mount motor (ie bafang 750/1000) work? The rear wheel has an internal 3 speed hub, so I’m thinking that would allow me to retain 3 gears to help move me along (6’3 115kg).

 

[sjpt]

Woosh do a 20" front XF07 kit: https://wooshbikes.co.uk/?hubkits

 

[E-Pashley]

Sorry to bombard the thread, but would a mid mount motor (ie bafang 750/1000) work? The rear wheel has an internal 3 speed hub, so I’m thinking that would allow me to retain 3 gears to help move me along (6’3 115kg).

I would recommend a mid drive kit (more torque) but you'd need to measure the ground clearance with the 20" wheels. Personally I'd use the tongsheng unit as it is smaller and the torque sensing setup will help protect those old hub gears. The down side is you need to put a bit of effort in to get assistance from the motor.
A 250 or 350 unit should provide plenty of grunt on this little bike. I think a 750W unassisted boost on this old bike would be scary (and brief).
As I mentioned before, I snapped one of these bikes before I was 10 years old - be gentle with her.

 

[WheezyRider]

Hi Bumreq, nice classic bike. Would be better if you could mount the battery on the down tube, in terms of balance. On my main bike I initially mounted the battery on the back rack, but it made the bike really tail heavy. So I 3D printed some brackets to go on the down tube to hold the battery and now the bike has a much better balance. Plus it allows me to use the back rack for cargo.

I would go for a front wheel kit. It's not ideal if you've got loads of power on the front wheel, but on a bike like this you don't need a lot of power and 250W is the legal limit anyway. Front wheel kits are really easy to fit and you don't mess up your rear hub and gears etc. You only have a short commute on the flat, so you don't need a lot of power. I've ridden mid drive e-bikes, but they are a lot more expensive and to me they feel unatural and are a lot of work to install compared to front wheel drive. Some people like them, but I think you need a high power model for it to feel ok, which is not what your bike would take. Go to a bike shop and ask to ride a mid drive bike to see what they are like. If you put a 750W Bafang mid drive on it, you will make the bike illegal and will probably break the bike. At peak power output, you could be putting far more more than 750W through the back wheel.

 

[Forty45]

I would think about uprating the brakes first. I have one of these (human powered only) and the old style side pulls don't inspire confidence at the best of times.

 

[Bumtreq]

I would think about uprating the brakes first. I have one of these (human powered only) and the old style side pulls don't inspire confidence at the best of times.

Sorry for the late reply. Any suggestions? I just rode the bike back from the office, worst day for it, but was the only time I was going to be near the office for the next couple of months. The brakes were terrible. Worse than I remember.

 

[Amoto65]

The brakes were terrible. Worse than I remember.

I agree the brakes are terrible, I have put some bmx brake blocks on mine.

 

[Woosh]

what is the tyre size?

 

[Amoto65]

what is the tyre size?

Tyre size is 451.

 

[Bumtreq]

I’ve been doing a bit more research and I might opt for a rear hub kit. Only because I don’t trust the front forks and any failure upfront could be dangerous on London roads (or any roads!).

Would this be an issue if the rear wheel is a slightly different size to the front? Also, any recommendations? I’m hoping for a 1000w as I’m quite a heavy rider, but open to options and suggestions.

cheers