20" front wheel hub motor, gearing questions !

[eHomer]

Having had mixed successes so far, I'm now thinking of electrifying my recumbent bike.

It's a long wheel base Burley Limbo, with a 20" front wheel and 26" rear wheel.

I realise the traction on the front wheel will be much less than the rear as it has so little weight on it.

Never the less, I would prefer to fit a front hub motor as I don't want to lose any of the gearing range in the nine speed hub.

I've so far converted a 250w 36v geared front wheel 700c hybrid, and a 750w 36v direct drive 26" rear wheel mountain bike.

For this project, I like the idea of a direct drive for quietness, but don't want the drag when pedaling with the motor off.

I've had a look around, and I'm wondering what is the highest wattage 36v front motor with planetary gearing and dragless freewheeling ? Would it be 350 watts ? This Ebay item is a 36v 350watt front wheel kit for £239.26 bin Latest 36V 350W Front Wheel Electric Bicycle Conversion Kits with LCD Display | eBay

My big concern is that if the same motor is supplied in 20, 26 and 28" rims, then would it be undergeared in the 20" size ? Or do they do something inside the motor ? Would I still get 15 to 18 mph ?

It's from Conhismotor, who I'm a little nervous about as well, as I still have their controller unit (and replacement), neither of which have I managed to get working at all.

So, (still waffling away here, sorry), can anyone recommend any alternatives ? The main object is to have the option of electric assist on the recumbent, hence using the front wheel, which could be quickly replaced with the standard wheel.

350watts might give me a slight edge over the 250, and yet still be completely dragless.

 

[Cyclezee]

Hi eHomer,

I have just sent you a PM.

Regards,

 

[banbury frank]

Hi If a customer came to me I would recommend the Bafang CST motor on the rear you can fit your existing freewheel and not loose traction in the wet Also there new sine wave controller and display

And the option off 36 v or 48 v with the controller so you can spin the motor faster with 48 volt


Bafang 36V500W CST Rear Driving Hub Motor - BMSBATTERY

S-LCD1 E-Bike LCD Meter - BMSBATTERY


S12S 500W Torque Simulation Sine Wave Controller - BMSBATTERY

KU63 Controller Case - BMSBATTERY

The ultimate set up


Frank

 

[shemozzle999]

This lists the circumference of your tyre, so you can calculate the minimum rpm of the motor you require to travel @25kph.

BikeCalc.com - How to calculate Bicycle Wheel Size

 

[Alan Quay]

BMS battery have the front version of the BPM in 350 watt, 328 rpm, 20 inch rim. You could almost certainly run it above 350 watt with right controller, how far you could push it before it fails I dont know for sure. I would guess 500 w would be fine.

According to my calculation, 328 rpm on 20 inch rim will be about 5400 mph. Then I did it again, and got 18mph (ish)

 

[jerrysimon]

Have you considered one of these. They are popular in recumbent bike. No power monsters but more than enough assistance to make pedaling easy.

Nice freewheel light and almost silent. Tongxiin 35V, 250W, 290RPM (easily get you to 18mph). You can buy them direct from China with controller, display panel etc for around £200 (suggest you buy two as shipping is the same so brings cost of each unit down to about £100 for just the motor or £150 with other bits). You can just buy the motors and then buy a programable controller to set you preffered settings.

Meets all your requirements of less drag, quiet, easy to remove etc. The one shown is the narrow 80mm one with 28H. They normally come in 100mm spacing with 36 flange holes.

This is their web site.

http://www.h9.com.cn/index.asp


Regards

Jerry

 

[eHomer]

Thanks everyone for the very rapid and helpful replies.

I'm now working my way through them and the links, but one quick question, how much does it cost to get a hub motor mounted into a 20" alloy front wheel, labour and parts ?

 

[Alan Quay]

BMS website is slow at the moment, but the BPM from them comes in a rim already, and they will do a 20 inch rim. About £140 delivered.

 

[jerrysimon]

Thanks everyone for the very rapid and helpful replies.

I'm now working my way through them and the links, but one quick question, how much does it cost to get a hub motor mounted into a 20" alloy front wheel, labour and parts ?

Depending on where you live I might be able to help you with a wheel build. I have been building small wheels 16-20" with front hub motors for a little while now

I am based in Cambridge.

Jerry

 

[Deleted member 4366]

You don't have to worry about messing up your gearing with a rear motor. The Q100C has a cassette spline 201 rpm., or you can use one of my MXUS cassette motors, which are about 250 rpm, if you want a bit more speed. Bafang also make a lightweight cassette motor, but I've not seen any for sale yet. Keyde make one ifyou want to take a chance on the reliability.

 

[jerrysimon]

Just to say I have been using a Keyde front hub motor with a programmable controller/throttle for the last three months on my daily commute and its been fine.

Like the Tongxins providing you keep the current limited to the max 12A for the Tongxins and around 8A for the Keyde they work perfectly in my experience.

Checkout the Keyde web site

www.keyde.com.


Regards

Jerry

 

[eHomer]

I've now explored some of the suggestions (thanks).

The BMS 350 watt, 328 rpm BPM 20" front wheel at £140 delivered is certainly one favourite.


...thanks for the offer of help with the wheel building Jerry, but I live in North East Norfolk, so about 120 miles away.


The 201rpm Q100c with cassette spline is a good parallel thought, it would get the drive wheel where the weight is, and it could still be a quick changeover to the unpowered original wheel if the gear cluster is the same.

I'm not sure if I'm reading the BMS website right on the Q100c, on the link Q100C CST 36V350W Rear Driving E-Bike Motor Wheel - BMSBATTERY for $109.18 (plus shipping), is that in a 26" rim ?

Does the cassette take an eight speed gear cluster ?

 

[Alan Quay]

You have to select the rim size at the bottom, (confusingly), and I would assume that the cassette spline will be standard, so you can put whatever you like on there. Cost me about £15 last time I bought an 8 speed.

 

[Deleted member 4366]

I've just looked at your bike again. It looks like it has narrow forks, which would rule-out most front motors. Did you check them?

 

[eHomer]

You have to select the rim size at the bottom, (confusingly), and I would assume that the cassette spline will be standard, so you can put whatever you like on there. Cost me about £15 last time I bought an 8 speed.

Yes very confusing, thanks for putting me straight Mike. Getting it in the wheel for that price certainly makes it really attractive.

I've just looked at your bike again. It looks like it has narrow forks, which would rule-out most front motors. Did you check them?

No, the photo is deceptive, the front forks are actually 100mm between dropouts.

I'm now mulling over the choice, front or back, but with BMS 500w 36v as the constant.

Another thought is at the back of my mind too, I still have the Hase recumbent trike, and that has 20" wheels all round, so a 20" front would keep my options open for that too. There's an incredibly expensive one on Ebay at the moment that's steadily rising with bids: HASE Klimax 5k

If I ever did switch the front wheel motor to that, my standard Hase Lepus would be a very similar setup. (in the 9 grand new league... wow...)


I'm still hoping as well that maybe my replacement Conhismotor controller and LCD display might work with a different 36v hall effect motor too, if it was some weird incompatibility with my other bike's motor.

 

[jerrysimon]

£900 is not really that expensive for a decent electric bike. A decent long range battery would cost £300-400.

Regards

Jerry

 

[RobF]

There's a poster on CycleChat who is trying to get rid of a couple of recumbents and a load of bits and pieces.

Everything Recumbent to go | CycleChat Cycling Forum

 

[eHomer]

Robf, Thanks for the cyclechat post link, quite a bargain for £1500 for the whole lot, but as the repliers have said, few people would want everything, except maybe a dealer.


Jerry, yes, £900 would be cheap, but I think it might go much higher. The seller says it was 9k new. A bit silly with no reserve maybe, it could go much lower at this time of year.

 

[jerrysimon]

I missed the 9K comment, yikes!

Jerry

 

[eHomer]

BMS website is slow at the moment, but the BPM from them comes in a rim already, and they will do a 20 inch rim. About £140 delivered.

I'm confused with the BMS website again !

All things considered, my best and most adaptable option was this 350watt 328rpm BPM motor already fitted in a 20" rim.

I can't find anything like that price of £140 delivered on the BMS website though.

The BPM 36V350W Front Driving E-Bike Motor Wheel with 328rpm and 20" rim at BPM 36V350W Front Driving E-Bike Motor Wheel - BMSBATTERY is $134.88

Whenever I put it in the basket though, the cheapest shipping is $166.54, which brings the total to $301.42, which is £187, and I guess the customs and it's "handling fee" will add another £50 or so, making £237....

JerrySimon's suggestion of a complete 20" kits via ebay then become more attractive, like this one Latest 36V 350W Front Wheel Electric Bicycle Conversion Kits with LCD Display | eBay

The whole lot except battery, for £238.94 delivered (though again, UK Customs might add a chunk to that).

It's from Conhismotor too, so makes me a little nervous, especially as their positive feedback on ebay is only 93% on over 500 sales.