Need more hill climbing power

[RustyKipper]

It's coming along albeit slowly. Its took 3 weeks of chasing BMS battery to get them to even send the new CST motor and controller. Unfortunately due to the poor packaging the motor wiring has been damaged, luckily the conductors seem ok even though the red and yellow wires are showing, I need to re-heat shrink them somehow.

I laced the motor into the rim yesterday and looks to be running nice and true. I couldn't get the controller to work, it seems without a display I have to link some of the wires that normally go to the display, I think 36V to lock and Rx to Tx, so might try this tonight. Then I just need to save up for some bigger Ah batteries, planning on 12 x 15Ah headway cells, I've bought one to see the size so am working out a battery enclosure. I could maybe reduce the shunt so that I can run the motor from my current 9Ah battery but wouldn't really gain much.

Planning ok keeping the front 250W motor for use around town / shared cycle ways ect but can use the rear 500W as well for the dreaded hills. The 250W motor stopped working on the way into work last week, I had to use the granny ring and pedal HARD, I managed 6 mph where I would normally do 10mph with the motor, it felt like pedalling with the brakes on! Very sweaty when I got to work, still did 30mph+ downhill! Turned out that the constant pounding of potholes fractured one of the pedal sensor wires.

I am however quite apprehensive about having 2 motors, if and when I get stopped by the boys in blue I need to do some serious blagging, like the rear motor is a regen brake, or maybe just have the rear 500W motor and re-label it 250W. I'm trying to keep the bike as stealthy as possible with some big rotors masking the motors but think my speed might give me away, I have done 40+ down one of the 20% descents before now without any motor assistance!

 

[mountain biker]

Sorry to hear about motor...I hope it can be replaced or repaired....so what's the word...did u do two motors...how do they work

 

[RustyKipper]

I’m getting very close fitting the second motor, the project is taking an age. The issue is that my current 9Ah battery won’t thank me for running a 500W motor yet alone 2 motors. I have the new cells ready but didn’t want to fit them over the back wheel as some of my commuting manoeuvres require a delicate touch, so I have been making 3 carbon fibre battery boxes to distribute the weight around the frame, they are now very close to being fitted, hopefully within the next couple of weeks.

I did throw the batteries in the rear carrier and go for a test ride a few months ago using both motors, I lashed up 2 throttles on the left hand side of the handlebar, they worked a bit like a plane or a boat, very cool but not very practical, something that did come to light was the amount of wheel spin from the from wheel upon hard acceleration so I am looking into cooking up some sort of traction control, this is also a big deal at the moment, my route home takes me through a woods and a couple of fields, in the mud the front wheel spins and drifts to one side or the other, twice I have nearly fallen into the river!

Hopefully the damage to the motor won’t be too much of an issue, I will put a few rounds of PVC tape around the damaded insulation to keep the damp out, I would prefer heatshrink but taking the wheel off after could prove a challenge. The internal insulation looks ok so will be safe at least, unfortunately the spring is damaged beyond repair.

 

[RustyKipper]

OK guys, after many months my AWD super hill climber is finally up and running, specs as bellow;

Front Hub: SWXK 250W
Rear Hub: Bafang CST 500W
Lower battery box: 2 x 15Ah Headway
Mid battery box: 4 x Headway 15Ah
Rear battery box: 6 x Headway 15Ah and 60/100A bms
Front controller: 6 FET CON61 mounted to steering stem
Rear controller: 12 FET CON121 mounted to outside of rear battery box
Battery Voltage: 36V
Total battery weight: 10Kg
Front brake: 203mm Disc / Avid BB7
Rear brake: 200mm Disc / Avid BB7
Front light: Magic shine 1000lm
Total bicycle weight: 33.5Kg (20Kg at rear wheel, 13.5Kg at front)

Front motor works solely from crank sensor and is used for shared cycle ways, pathways and were the road surfaces are particularly awful, there is a bypass switch on the handlebar to switch the crank sensor out so obstacles and pedestrians can be safely negotiated.
Rear motor is operated by throttle on left had side of handlebar to enable gear changing with right hand.
Machined brake levers enable the standard kit type switched brake lever bodies can be used with MTB type levers
Machined adaptor plate to mount rear calliper to frame and enable use of 200mm rear disc
All battery boxes Plywood / Carbon fibre composite
Steel hoop on handlebars for front light mount and carbon fibre box containing the battery isolator switch and IP67 charge socket.
Battery charger is on a timer so I don’t have to trudge out in the rain before going to bed to turn it off.

The reason for the AWD were due to the very hilly terrain I have on my daily 25 mile per day commute in and out of central Sheffield. Also there is a very muddy uphill track across a farm field that requires both wheels to be driven as rear wheel only just results in wheel spin.
The ride into Sheffield is predominately downhill but the road is quite high altitude and is directly looking at the Pennine range so there is often a fairly savage headwind. The home commute is 700 – 800 foot climb depending on my route, fine on a Sunday morning but not at the end of the working day when I’m tired and hungry.
I have done 4000 miles now on the front motor alone before recently adding the rear motor and larger battery packs, this 250W motor cruised at about 18-19 mph with fair pedal effort and gave an average speed of about 16 mph according to the computer. Battery consumption has been around 14.4Wh/mile. The fastest I have ridden is 42 mph downhill head down pedalling like crazy and squealing like a girl!


Results with the new twin motor setup:

Bit of a mixed bag really. Cruising speed is very good, on the flat (ok there isn’t any round here but flatish) with a decent pedal input it seems happy at between 22 and 24mph, and takes a noticeable gradient for this to drop. The rear motor does take a fair bit of juice from the battery, it seems to be averaging about 21 Wh/mile from looking at the charge profile. I turn the front motor off above 18 mph as it will be spinning uselessly, I have always done this, in fact I have found in the past using throttle only I can get an extra 30% range.
The CST motor is very quiet and very smooth although the power comes in a bit abruptly sometimes.
It is quite hard to get both motors to work simultaneously, I think the Headways suffer from pretty appalling voltage sag, so if the front motor is running the rear will not engage unless I am doing close to the front motors maximum speed so the current tails off or I pull one of the brake levers. I think this may be compounded by the front controller having a 19A shunt mod.
It does climb hills quite well, it seems to handle a 13% hill (doesn’t sound much in %) at around 16 – 18 mph with hard pealing, from memory doing this on a regular non e-mountain bike would be about 3- 4 mph.
For the last 4000 miles when using the little SWXK 250W I have used a slightly different route as per my original post. I found that the cars would queue up behind me waiting to pass then clog it going up the hill leaving me in a thick black choking cloud of diesel smoke, this seemed somewhat unhealthy! I now ride an extra 4 miles further out in the sticks, the roads are both quieter and have a lesser gradient, the steepest parts are around 13% but there is less of an urgency to climb them.
Downsides of my awd setup are the heavy power consumption meaning the battery pack needs charging at work which I was hoping not to do. The biggest issue is down to the roads, in the dark it is quite impossible to miss all the potholes and the bike really crashes over them, I’m going to either break a wheel or the frame or myself. A lot of the roads are like the surface of the moon, others are like spending half an hour riding over a cattle grid with the odd missing rung, also the frame (aluminium) is flexing alarmingly with the rigid mounted batteries.
So in conclusion I’m happy with the performance and the looks, even the weight balance seems quite good, if all batteries were over the back wheel it would be a right handful. But it’s just not practical on the roads of the North of England for a daily commute.
I’m wondering about a mid drive next with a mid frame mounted battery ( not Headways) so the front and rear of the bike will be able to handle the potholes better, also it would make fixing punctures in the pitch dark easier! I do however have reservations about how long the chain (9 speed) will last with the extra power, currently the chain is badly stretched after 2 or 3 months. I think the mid drive motor would have a easier time as it won’t be bashed over pot holes and the gearing would be better. The SWXK groans and vibrates the handle bars when climbing at less than 9 mph.
The battery packs are heading for the for sale section soon to fund the next modification.
As a tool this bike with a 250W motor has worked flawlessly as a means of commuting, so much so that using the car is very much a last resort even in the pouring rain we’ve had for the last few months. The little 250W motor is starting to show some wear and tear now, the bearings are getting quite noisy with quite a bit of play, the wheel is not as round or true as it once was.

Interestingly running both motors and pedalling like a demon gets the 14 mile home journey completed in 45 minutes, using the 250W motor only gets me home in 50 minutes....Hmmm

 

[craneplaneguy]

A fellow aircraft builder friend of mine who works with carbon fiber a lot, real carbon fiber, discovered a look a like. It's vinyl sheeting he gets in a roll, and self adhesive. When properly adhered to a thin aluminum sheet or tube (where it's not practical to use the real deal CF), you would swear the part is CF! It's strictly cosmetic, just for looks, but doesn't weigh anything.

Great looking work, I like all the cut out's/lightening holes you did.

 

[RustyKipper]

View attachment 1Check out my tool kit, lots of holes to make it lighter!

The annoying thing is my carbon is real but looks totally fake!

anyone know why sometimes my pictures won't show when I upload them?

 

[d8veh]

It looks great. There's a company in London called Insatinternational.com that will make a custom battery for you using 18650 cells. He has all the different ones from Sony, Samsung and Panasonic, so you can get whatever power or capacity you want. They made a 36v 30 cell high power pack for me for a Brompton conversion. It cost £210 including BMS and shipping. Other cells would have been cheaper.

Do you really need two motors? I ran a 500w CST at 36v 30 amps, which gave enough torque to climb the very steep hills we have around Telford. I also have a 2WD with a pair of Q100H's at 15 amps each that will eat any hill.

 

[RustyKipper]

I'll definitely look at them for a battery that's a good price, I chose the Headways as I thought they would run two motors easily.... but boy are they heavy!

Do I really need 2 motors? not really, I do need to pass through muddy wooded areas and a ploughed field but in reality the bike gets so clogged with mud and I look like a motocross rider when I get home so generally take a longer route to avoid these area's in the winter, 1 motor would work fine but 500W is just too heavy in a wheel. I spent several weeks before Christmas with the 500W motor fitted in the back wheel but not connected, I needed it so I could fit a rear disc brake as every time it rained the oil would wash off the chain and onto the rim, the rear brakes would stop working then the front pads would wear so fast I would have to stop on the way home to adjust them. Even just with the weight of the motor in the back the ride was a lot worse, on 2 consecutive nights I compressed my spine and jarred my kidneys (well bad stuff was going on inside) 250W is not enough when I'm climbing hills out in the sticks, 500W is way better, its going to be hard to go back to 250W.

 

[wineboyrider]

Your ride and terrain screams mid drive. A BBSHD with proper gearing would probably getr done.

 

[Phil G]

I would like to post my experience with hill climbing as this was a subject I wanted information on before I made the conversion of an old aluminum bike.
My +20km trip involves a 9.3km climb from about 12mts to 396mts and this can be achieved within 30min depending on wind conditions
(the next 6km steep descent takes 10min, no pedaling nor motoring and a lot of fun!). Maximum gradient on this road is 15% according to mapometer.com.
Bike weight around 25kgs.
My weight around 80kgs.
Motor: GNG 36v 350w brush-less mid-drive (stock kit with stock controller, no modifications)
Battery: Ping 36v 15Ah (over this hill, with this weight and motor, the range I estimate to be around 30kms)
The range is an estimate but I have traveled up to 28kms round trip over this hill before recharging.
Gearing: 7 speed 14T – 34T. On the flat I can average 35 to 37kmh top speed.
As an aside, I took up this mode of travel because at the age of 58 I discovered the pain in my knee was due to osteoarthritis.
My doctor and physiotherapist said that the pain could be relieved by bicycling because it will builds muscle tone and give space to the joint.
And its working

 

[RustyKipper]

Hi Phil, that’s really interesting about your knee, I’m in my early fifties and my left knee is in quite bad shape, I had to give up driving a manual car in favour of an automatic so I didn’t think for a minute that I would be able to cycle again but found as long as I took it fairly easy the pedalling did not aggravate my knee, in fact now I’m riding 200Km a week my knee has been better than it’s been for years, I thought I must have been imagining it 

I’m definitely looking for a mid drive, I like the sound of the GSM CD 250W motor, My commute is pretty manic, lots of kerb jumping, pot holes and joggers wearing headphones so probably best to stay legal in case of a conflict hence 250W.
Also I don’t want an lcd, if I look down at the handlebars..bang..I’ve hit a pot hole ,glass bottle or a broken car spring or some clown has pulled out in front of me so might stick with my current controller, it has 3 power levels that I can control with a finger switch on the handlebars without looking, not sure how well it will work with the CD motor but that’s part of the fun of building your own e-bike isn’t it, the experimenting.

It’s good to see your reel world figures, on the flat I’m cruising slightly slower than you at 28 – 32Kmh, I think this is about the point where the motor runs out of steam, it does however mean I’m pulling almost no current at this speed so it’s good for range.

That’s quite an impressive climb up to 396m! My steed would be lugging badly at that kind of gradient, it would be showing its displeasure by the motor vibrating the handlebars!

Currently I have a nine speed cassette so could do with changing to a seven speed for the stronger chain.

 

[Comfortzone]

RustyKipper - GSM CD from Woosh Bikes UK ? I have one but after securing the wires where they exit from the motor with a tiewrap inside the case,
the motor locks solid when trying to move off.
That sounds like a winding short, but woosh lost interest in my email on the subject, so I backshelved the GSM CD while I fitted a front wheel magicpie4.
The GSM has little waterproofing, if any, just scrappy bathroom sealant inside the motor case. I'm hesitant to rip apart the motor case- but thats whats needed to investigate thoroughly.

 

[RustyKipper]

Yes GSM CD from Woosh Bikes UK, that does indeed sound like a short, obviously you have tried to spin the motor with the wires completely disconnected?

It would be interesting to know where the fault is, ie the motor windings or the cables shorting to the case, obviously if you take it apart you can't send it back.