2WD in snow

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RustyKipper   100 W

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2WD in snow

Post by RustyKipper » Jan 15 2021 2:59pm

OK, I took my special winter 2WD (2 x 250W hubbies) with studded tyres on the 14 mile trek to work this morning only to find it hopeless in the snow, it was about 5 inches deep :shock: there was absolutely no steering, coming home the roads were sheet ice and the grip was out of this world, it was almost like riding on a dry road!
I figure that there is too much power being sent to the front wheel so its constantly breaking traction, I'm going to fit a pot on the handlebars tomorrow to reduce the throttle signal to the front motor but wonder if there might be a better way such as limiting the current, might be a bit tricky as I would have to vary the shunt resistance.

Had a bit of a hairy moment riding home, I was hoofing it down a country road way too fast when the road suddenly turned into frozen slush, I completely lost control, I was doing well over 20mph throwing the steering one way then the other trying to stay aboard but with each lump of ice I would ricochet in a different direction, it was at that point I realized that the rear brake cutoff wasn't working so couldn't cancel the cruise control so was speeding up and knowing if I used the front brake I would be straight on my face, in the end the bike slid sideways into the frozen snow covered verge letting me have enough stability to use the front brake and regain some control and carry on.....that was exiting :P :P :P
2017 Cotic BFE hardtail MTB
Sram 9 speed twist grip
CST rear drive
5P10S 16Ah home built battery with built in block heater
Con121 12FET controller
Sapim 2.3mm black stainless steel spokes
Sunringle 26 inch rims
26 x 2.1 Swarble Marathon Mondail tires
650gm downhill inner tubes --essensial
Shimano Zee 4 pot calipers front and rear
200mm / 203mm rotors
Thudbuster suspension seat post -- essensial
150 Mile per week muddy commute

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motomech   1.21 GW

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Re: 2WD in snow

Post by motomech » Jan 15 2021 10:00pm

I ran dual Cutes for almost a decade. Tried many configurations and started w/ one throttle/2 controllers and different ways to provide "differential" power. None of that really worked very well for me.
In the end, I just did it the simplest way possible, 2 Batt.s, 2 controllers and 2 throttles.

viewtopic.php?f=2&t=88304&p=1288657&hil ... s#p1288657
Motomech '11 Motobecane Fathom team, frt. mounted, recycled SWX02 from a Jump rental, 14S (52V nom.) Turnigy LiPoly, PSW Power 9-FET 20A controller. Mean Well HLG-320H-54A, Schwalbe Marathon's, 27 to 28 MPH.

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amberwolf   100 GW

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Re: 2WD in snow

Post by amberwolf » Jan 16 2021 2:28am

I'll second the separate throttles. It doesn't take long to make it second nature to control the front and rear separately; I used them paired with the same end's brake levers--front motor and brake on right, rear motor and brake on left, for CrazyBike2. Worked even in just-starting-misting rain conditions with car oil slicks on the road, etc., as well as in the flooding rain conditions (high enough to make the sidewalks invisible).

Way back I had an idea for something that would monitor torque on the front motor via a special torque-arm setup with a strain-gauge in it, and if the torque didn't go up with the current for that controller, it'd rollback the throttle to prevent wheelspin. It would have a secondary sensor for wheelspeed to compare front and rear wheel speeds, and if they differed by more than a certain tiny percentage, the same thing would happen. I never messed with designing and trying it, because it was complicated and separate throttles worked fine for me.

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LeftieBiker   100 kW

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Re: 2WD in snow

Post by LeftieBiker » Jan 16 2021 3:21am

You aren't running too much pressure in the tires, are you? What kind of studs?
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RustyKipper   100 W

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Re: 2WD in snow

Post by RustyKipper » Jan 16 2021 8:38am

I thought about 2 throttles but I'm kind of short of real-estate on the handle bars and I'm trying to keep it simple.

I've added a thumb operated pot on the right side of the bars that I can operate with my thumb so giving me a range of 0 - 100% of what's getting sent to the rear.

I took the bike out earlier today but the roads are just sheet ice and frozen slush with no fresh snow so couldn't test it properly, but man was I enjoying it!! especially the wide mouthed looks I was getting from people who could barely stand up 8) While I was concentrating I kept pressing the throttle instead of the brakes which did not have the desired effect (scream if you want to go faster) :shock: hence trying to keep it as simple as possible.

What I may of forgotten to mention is that where I live is VERY hilly, in these conditions only 4x4's can get up the hills, the steepest is getting on for 20%. I've ridden this bike up this very hill after the ice has been polished by dozens of cars trying to get up, the bike didn't even notice the ice.

My one issue is that I hate the controllers I'm using, I think they are CON611, they have a very annoying 'throttle lag' I've used CON61's in the past and these were great.
Throttle pot.JPG
Throttle pot.JPG (1.88 MiB) Viewed 409 times
(Yellow button is the cruise set)

Edit. Tires are swarble marathon winter, pressure probably slightly high at 40 psi (rating 30 -70psi), once on the main roads I have several miles of clear tarmac so want to preserve the studs as much as posible.
2017 Cotic BFE hardtail MTB
Sram 9 speed twist grip
CST rear drive
5P10S 16Ah home built battery with built in block heater
Con121 12FET controller
Sapim 2.3mm black stainless steel spokes
Sunringle 26 inch rims
26 x 2.1 Swarble Marathon Mondail tires
650gm downhill inner tubes --essensial
Shimano Zee 4 pot calipers front and rear
200mm / 203mm rotors
Thudbuster suspension seat post -- essensial
150 Mile per week muddy commute

fatty   100 W

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Re: 2WD in snow

Post by fatty » Jan 16 2021 6:49pm

amberwolf wrote:
Jan 16 2021 2:28am
Way back I had an idea for something that would monitor torque on the front motor via a special torque-arm setup with a strain-gauge in it, and if the torque didn't go up with the current for that controller, it'd rollback the throttle to prevent wheelspin. It would have a secondary sensor for wheelspeed to compare front and rear wheel speeds, and if they differed by more than a certain tiny percentage, the same thing would happen. I never messed with designing and trying it, because it was complicated and separate throttles worked fine for me.
Modern controllers can mitigate wheelspin directly via overspin protection (Adaptto, maybe PV next-gen?) or acceleration limit (ASI/Grin, Nucular).
Don't take advice from:
there is no difference between a mean well CC/CV power supply and a device sold as a charger. they operate in EXACTLY the same way
Testing has demonstrated that ordinary rim brakes thermally outperformed all but the best disc brakes...You'll always add weight and cost, while not equalling the capabilities of comparable rim brakes, if you use discs

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amberwolf   100 GW

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Re: 2WD in snow

Post by amberwolf » Jan 16 2021 11:22pm

They have a way to monitor speed of two controllers and compare them to a "difference limit"? If not, I'm not sure how they would be able to do this kind of "traction control".

If they just have an "overspeed" protection, that won't do what's needed for this purpose. That kind of protection only prevents spinning a motor faster than some limit, typically to prevent motor or drivetrain damage from spinning faster than a certain RPM.

fatty   100 W

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Re: 2WD in snow

Post by fatty » Jan 18 2021 12:28am

amberwolf wrote:
Jan 16 2021 11:22pm
,They have a way to monitor speed of two controllers and compare them to a "difference limit"?
Adaptto and Nucular can network. While true two wheel traction control would compare and correct, and I'm certain they don't, but see below...
amberwolf wrote:
Jan 16 2021 11:22pm
If they just have an "overspeed" protection, that won't do what's needed for this purpose. That kind of protection only prevents spinning a motor faster than some limit, typically to prevent motor or drivetrain damage from spinning faster than a certain RPM.
While the traditional meaning of motor overspeed protection is the traditional rpm limit as you say, Adaptto and PV instead mean an acceleration limit as per the other controllers. Adaptto has explicitly described their overspeed protection as traction control, and PV is claiming the same for the next-gen. But in the absence of greater detail, we should call all these features "acceleration limit".

In this use, the controller simply monitors motor acceleration in rpm/s. The motor acceleration limit can be configured for what full throttle with hot battery produces while maintaining traction.
If the driven tire later loses traction under throttle (burnout, gravel, ice), the motor will 'skip' to a higher rpm, exceeding the acceleration limit, and the controller should roll back or cut power to regain traction.
Don't take advice from:
there is no difference between a mean well CC/CV power supply and a device sold as a charger. they operate in EXACTLY the same way
Testing has demonstrated that ordinary rim brakes thermally outperformed all but the best disc brakes...You'll always add weight and cost, while not equalling the capabilities of comparable rim brakes, if you use discs

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amberwolf   100 GW

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Re: 2WD in snow

Post by amberwolf » Jan 18 2021 1:00am

Ah...that would probably be sufficient for this usage. :)

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motomech   1.21 GW

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Re: 2WD in snow

Post by motomech » Jan 18 2021 1:27am

Back to the Fred Flintstone approach. I would point out to the OP, that I use "left-hand" throttles occupying the space where the frt. chain-ring shifter was.
Motomech '11 Motobecane Fathom team, frt. mounted, recycled SWX02 from a Jump rental, 14S (52V nom.) Turnigy LiPoly, PSW Power 9-FET 20A controller. Mean Well HLG-320H-54A, Schwalbe Marathon's, 27 to 28 MPH.

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RustyKipper   100 W

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Re: 2WD in snow

Post by RustyKipper » Jan 18 2021 7:10am

motomech wrote:
Jan 18 2021 1:27am
Back to the Fred Flintstone approach. I would point out to the OP, that I use "left-hand" throttles occupying the space where the frt. chain-ring shifter was.
I do exactly the same so that I can change gear when under power on steep hills or accelerating into traffic, the front chain ring shifter has been relocated to under the seat.
2017 Cotic BFE hardtail MTB
Sram 9 speed twist grip
CST rear drive
5P10S 16Ah home built battery with built in block heater
Con121 12FET controller
Sapim 2.3mm black stainless steel spokes
Sunringle 26 inch rims
26 x 2.1 Swarble Marathon Mondail tires
650gm downhill inner tubes --essensial
Shimano Zee 4 pot calipers front and rear
200mm / 203mm rotors
Thudbuster suspension seat post -- essensial
150 Mile per week muddy commute

User avatar
RustyKipper   100 W

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Posts: 115
Joined: Apr 13 2015 5:40am
Location: South Yorkshire UK the land of flat caps and wippets

Re: 2WD in snow

Post by RustyKipper » Feb 03 2021 7:46am

Bit of an update,

I managed to get some miles on the 2x2 this morning, we had about 3 inches of snow yesterday but it was way to dangerous riding on the freeway as it was a full on blizzard, driving the 4x4 I couldn't see a thing so if I was on a bike I would of ended up somewhat dead. Any how, this morning was a different story, so, news on the thumb control.... it works an absolute treat, the bike was unrideable before slithering every which way but loose when the front was getting the same power as the rear, the thumb control is a bit fiddle to set so I might replace it with a 2 or 3 position switch a bit like a hill decent control in 4x4x's.

Tonight should be interesting as I have to climb a steep mud hill at a farm with a significant camber that people and horses can't even walk up, my rear wheel drive bike will only just make it up with knobbly tires, even so it's usually crabbing sideways for nearly 1/4 of a mile, with a small amount of front drive it should be much easier....tune in soon to see if it works.

Edit.

2WD rocks!! It gets up the muddy incline with ease, I can dial in the right amount of power to balance grip and steering, still getting a surprising amount of rear wheelspin (snow tires not knobblies) and still clawing my way up side ways but man is it fun :P
2017 Cotic BFE hardtail MTB
Sram 9 speed twist grip
CST rear drive
5P10S 16Ah home built battery with built in block heater
Con121 12FET controller
Sapim 2.3mm black stainless steel spokes
Sunringle 26 inch rims
26 x 2.1 Swarble Marathon Mondail tires
650gm downhill inner tubes --essensial
Shimano Zee 4 pot calipers front and rear
200mm / 203mm rotors
Thudbuster suspension seat post -- essensial
150 Mile per week muddy commute

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