Convert a double-motorized wheel electrical bike

[steelzhu]

As we all know, when a bike turns left or turn right, the front wheel should be faster than the rear wheel.

I didn't know this and after thinking about it for a while now, still can't visualize why this is true. Can someone help out here and offer up a quick explanation or link? Thanks!

For example: If you ride a bike and turn around, you will find the front wheel is always in outside and the rear wheel is always in inside.

BW my problem is just happen when I want to turn around on a narrow street unless I cut off one of the hubmotor.

 

[teklektik]

For example: If you ride a bike and turn around, you will find the front wheel is always in outside and the rear wheel is always in inside. If you can turn right/left fron wheel 90 degree then riding, you will find just front wheel moves and the bike turns around.
BW my problem is just happen when I want to turn around on a narrow street unless I cut off one of the hubmotor.

Okay - that was very clarifying. You are talking about very low speed steering (by turning the bars) not cornering (by leaning) while at speed.

In that situation Jeremy's remarks about DD vs gear motor are spot on.

 

[steelzhu]

Someone give me a suggestion:
"This is one of the main design problems with 2WD bicycles and motorcycles. You might consider wiring a suitable resistor into the rear wheel throttle signal wire. I'd consider starting with a 5-10% decrease in rear wheel throttle signal voltage (you might try testing this with a variable resistor). An overall decrease in rear wheel speed would seem to limit the apparent advantages of having a 2WD bicycle. However, the front wheel would (hopefully) still offer traction if, and when, the rear wheel loses grip. Btw, 2WDbike designs offer little, if any, increases in top speed. Improved acceleration and traction are what 2 and 4WD designs excel at. "
But I still want to Maybe I can get a switch with the hall sensor to controll the rear hub motor on/off when I turn left/right.

 

[Lebowski]

I think the key to an e-bike with 2 motors is to have 2 controllers each with torque based throttle, operating of 1 throttle.
In such a configuration the speeds of the 2 motors can be independent of each other. Each motor will produce
the torque as requested by the rider, independent of wheel speed.

The controller IC I developed (see http://endless-sphere.com/forums/viewtopic.php?f=30&t=36602) has all the options
you need for a good 2 motor e-bike. With 2 controllers build around my IC's, one controller can be connected to the
throttle on the handle bars. The second controller then receives the throttle signal over a (3 or 4 wire) CAN bus.
Each wheel can be configured independently for what it's maximum torque is and how it responds to the throttle.

 

[d8veh]

I think that you'r going in completely the wrong direction. I'm sure that your problem comes from the two massive gyroscopes on your wheels combined with steering geometry that means that you need high effort to get the bike to lean. I had a motorcycle that also didn't want to lean over, which I improved by fitting wider handlebars and changing my steering technique to apply concious counter-steering to make the bike lean over to initiate the turn. You'd be surprised how many regular cyclists/motorcyclists don't know that you apply effort to the handlebars to the right when you want to steer to the left. So my advise is to try positive counter-steering to initiate the turn, and if that works, fit wider bars to make it more natural.

 

[steelzhu]

I think the key to an e-bike with 2 motors is to have 2 controllers each with torque based throttle, operating of 1 throttle.
In such a configuration the speeds of the 2 motors can be independent of each other. Each motor will produce
the torque as requested by the rider, independent of wheel speed.

The controller IC I developed (see http://endless-sphere.com/forums/viewtopic.php?f=30&t=36602) has all the options
you need for a good 2 motor e-bike. With 2 controllers build around my IC's, one controller can be connected to the
throttle on the handle bars. The second controller then receives the throttle signal over a (3 or 4 wire) CAN bus.
Each wheel can be configured independently for what it's maximum torque is and how it responds to the throttle.

So good idea! I will learn it later. Maybe we can get a programe to let the 2 motors have the same torque not the same power or speed.

 

[steelzhu]

I think that you'r going in completely the wrong direction. I'm sure that your problem comes from the two massive gyroscopes on your wheels combined with steering geometry that means that you need high effort to get the bike to lean. I had a motorcycle that also didn't want to lean over, which I improved by fitting wider handlebars and changing my steering technique to apply concious counter-steering to make the bike lean over to initiate the turn. You'd be surprised how many regular cyclists/motorcyclists don't know that you apply effort to the handlebars to the right when you want to steer to the left. So my advise is to try positive counter-steering to initiate the turn, and if that works, fit wider bars to make it more natural.

If I can't fix the problem thoroughly. I think there are some ways to relieve the problem:
1. Let the front wheel faster than rear wheel
2. As you said: fit wider bars to make it more natural
3. Get a switch turn off the rear motor when turning.

 

[d8veh]

Try the counter-steering technique as it doesn't cost anything. When you want to make a significant turn, you give a big push on the handlebars in the opposite direction to what you want to turn. This force overcomes the gyroscopic force of the wheels and makes the bike lean over so that you can turn in the direction that you want to go. It sounds a bit weird, but when you try it, it'll make a lot more sense. I'm sure that your problem has nothing to do with speed of motors etc and it's only because of the rotational inertia of your rather heavy wheels - mainly the front one.

 

[teklektik]

For example: If you ride a bike and turn around, you will find the front wheel is always in outside and the rear wheel is always in inside. If you can turn right/left fron wheel 90 degree then riding, you will find just front wheel moves and the bike turns around.
BW my problem is just happen when I want to turn around on a narrow street unless I cut off one of the hubmotor.

If I can't fix the problem thoroughly. I think there are some ways to relieve the problem:
1. Let the front wheel faster than rear wheel
2. As you said: fit wider bars to make it more natural
3. Get a switch turn off the rear motor when turning.

I'm not entirely convinced that you have correctly identified 'the problem'. You seem to indicate that your difficulty lies only at very low speeds or when essentially walking the bike. However, you have what appears to be a fairly powerful bike with no means to moderate the power or remedy any throttle linearity issues. I suspect that a large part of the difficulty may be in trying to perform slow speed operations with a twitchy throttle - the same well-known issue other folks have with a single powerful motor. Before you pursue 2WD-specific modifications, I think you might benefit from spending time addressing more conventional bike issues. It's possible that with better low speed power control, any 2WD-specific issues may not appear as prominent.

For instance, I would recommend starting with a DPDT on-off-on toggle switch and wire up each half as a three-speed switch on your controllers. This should give you much more refined throttle control at low speed and may minimize some of your handling difficulty. If you still have some torque-steer problem remaining, you can unbalance the low speed controller settings to say 30% rear and 35% front - at low speed this will effectively reduce the rear throttle setting by 15% (30/35 = 85%).

 

[steelzhu]

Try the counter-steering technique as it doesn't cost anything. When you want to make a significant turn, you give a big push on the handlebars in the opposite direction to what you want to turn. This force overcomes the gyroscopic force of the wheels and makes the bike lean over so that you can turn in the direction that you want to go. It sounds a bit weird, but when you try it, it'll make a lot more sense. I'm sure that your problem has nothing to do with speed of motors etc and it's only because of the rotational inertia of your rather heavy wheels - mainly the front one.

Thanks a lot
When I turnning , my speed is very slow just like walk. And I have buit a e-bike with a front wheel hub motor, there aren't any problem.
So I think " gyroscopic force of the wheels" maybe is not the main reason.

 

[steelzhu]

As we all know, hydraulic brakes have a better braking performance than mechanical brake.Too many E-bike fans would like to use hydraulic brake replace of the normal brake. Usually we met some troubles in the process of their hydraulic brake conversion with papamotor kits.
1 Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake.
2 The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper.
3 Non-international standard adapter won’t be compatible with the disc brake rotor.
4 Hydraulic brake doesn’t have the function to cut off the motor power.
I will squeeze some time to mount a rear hydraulic brake (Shimano BR-M446) to my E-bike this weekend.

 

[steelzhu]

I drive at a fast start, and the top speed can reach 62KM/H on the street road.
[youtube]http://youtu.be/Sq5_KJdA2MM[/youtube]
May you can check detail info in http://endless-sphere.com/forums/viewtopic.php?f=2&t=45339

 

[amberwolf]

1 Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake.
2 The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper.
3 Non-international standard adapter won’t be compatible with the disc brake rotor.
4 Hydraulic brake doesn’t have the function to cut off the motor power.
I will squeeze some time to mount a rear hydraulic brake (Shimano BR-M446) to my E-bike this weekend.

You might want to peruse various ES threads where most of these things have been easily overcome, some with standard off-the-shelf items (including a hydro type inline ebrake switch).

Also, hydro braking might be able to be "harder", but it is not necessarily "better" than mechanical systems. Lower end hydros and higher end mechanicals often overlap in capability ranges.

 

[GrayKard]

As we all know, hydraulic brakes have a better braking performance than mechanical brake.Too many E-bike fans would like to use hydraulic brake replace of the normal brake. Usually we met some troubles in the process of their hydraulic brake conversion with papamotor kits.
1 Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake.
2 The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper.
3 Non-international standard adapter won’t be compatible with the disc brake rotor.
4 Hydraulic brake doesn’t have the function to cut off the motor power.
I will squeeze some time to mount a rear hydraulic brake (Shimano BR-M446) to my E-bike this weekend.

It's best to start a new thread and not change the topic in mid thread.

Gary

 

[steelzhu]

As we all know, hydraulic brakes have a better braking performance than mechanical brake.Too many E-bike fans would like to use hydraulic brake replace of the normal brake. Usually we met some troubles in the process of their hydraulic brake conversion with papamotor kits.
1 Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake.
2 The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper.
3 Non-international standard adapter won’t be compatible with the disc brake rotor.
4 Hydraulic brake doesn’t have the function to cut off the motor power.
I will squeeze some time to mount a rear hydraulic brake (Shimano BR-M446) to my E-bike this weekend.

It's best to start a new thread and not change the topic in mid thread.

Gary

You are right

 

[steelzhu]

Wow,Looking forward to see your new thread about hydraulic brake conversion

 

[Cyclebutt]

Try the counter-steering technique as it doesn't cost anything. When you want to make a significant turn, you give a big push on the handlebars in the opposite direction to what you want to turn. This force overcomes the gyroscopic force of the wheels and makes the bike lean over so that you can turn in the direction that you want to go. It sounds a bit weird, but when you try it, it'll make a lot more sense. I'm sure that your problem has nothing to do with speed of motors etc and it's only because of the rotational inertia of your rather heavy wheels - mainly the front one.

Thanks a lot
When I turnning , my speed is very slow just like walk. And I have buit a e-bike with a front wheel hub motor, there aren't any problem.
So I think " gyroscopic force of the wheels" maybe is not the main reason.

So.. how does it handle without throttle applied? Have you ridden around using pedal power only?

 

[steelzhu]

So.. how does it handle without throttle applied? Have you ridden around using pedal power only?

I just use 1 throttle to control 2 hub motors So 2 hub motors with almost the same speed.

 

[steelzhu]

As we all know, hydraulic brakes have a better braking performance than mechanical brake.Too many E-bike fans would like to use hydraulic brake replace of the normal brake. Usually we met some troubles in the process of their hydraulic brake conversion with papamotor kits.
1 Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake.
2 The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper.
3 Non-international standard adapter won’t be compatible with the disc brake rotor.
4 Hydraulic brake doesn’t have the function to cut off the motor power.
I squeeze some time to mount a rear hydraulic brake (Shimano BR-M446) to my E-bike this weekend.
Material configuration as below:
Bicycle (GIANT ATX690) *1
26inch Rear motorized wheel *1
Disc brake *1
Shimano BR-M446 hydraulic rear brake *1
Some necessary accessories

My solution to the above 4 questions:
Q1. Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake?
a Use F160 bracket to replace of the original R160 bracket.

b We have to make some modification on the basis of original brake bracket.

Q2. The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper?
a Shorten the original axle spacer to 18mm first.

b Due to the size of fixed brake caliper is too thick, it’s almost near to the hub motor cover. So we have to use a special designed 4mm spacer to lengthen the space.

Q3. Non-international standard adapter won’t be compatible with the disc brake rotor?
We use a special designed 10mm adapter, which is suitable for installing 44mm diagonal Shimano brake rotor

Installation steps:

Besides, we also install one pair of torque arms for the safety.

Q4. Hydraulic brake doesn’t have the function to cut off the motor power?
The Shimano446 brake handle can’t cut off the motor power, so we choose to install one right E-brake handle which can cut off the motor power directly.

 

[steelzhu]

As we all know, hydraulic brakes have a better braking performance than mechanical brake.Too many E-bike fans would like to use hydraulic brake replace of the normal brake. Usually we met some troubles in the process of their hydraulic brake conversion with papamotor kits.
1 Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake.
2 The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper.
3 Non-international standard adapter won’t be compatible with the disc brake rotor.
4 Hydraulic brake doesn’t have the function to cut off the motor power.
I will squeeze some time to mount a rear hydraulic brake (Shimano BR-M446) to my E-bike this weekend.

It's ready now! Anyone is interesting to it can check my new post : http://endless-sphere.com/forums/viewtopic.php?f=2&t=45707

 

[amberwolf]

http://www.endless-sphere.com/forums/viewtopic.php?p=664762#p664762

1 Hydraulic brakes can’t be mounted to the original bracket of their mechanical brake.
2 The space between the hub motor cover and brake rotor is not enough for placing the hydraulic brake caliper.
3 Non-international standard adapter won’t be compatible with the disc brake rotor.
4 Hydraulic brake doesn’t have the function to cut off the motor power.
I will squeeze some time to mount a rear hydraulic brake (Shimano BR-M446) to my E-bike this weekend.

You might want to peruse various ES threads where most of these things have been easily overcome, some with standard off-the-shelf items (including a hydro type inline ebrake switch).

Also, hydro braking might be able to be "harder", but it is not necessarily "better" than mechanical systems. Lower end hydros and higher end mechanicals often overlap in capability ranges.

 

[steelzhu]

Also, hydro braking might be able to be "harder", but it is not necessarily "better" than mechanical systems. Lower end hydros and higher end mechanicals often overlap in capability ranges.

hydro braking might be able to be "harder"--that's right I think it is better in 1000w ebike!

 

[steelzhu]

Sometimes I have to ride in the darkness. So I try to mount such a 9W 48V LED light on the bicycle.
This light helps a lot when we ride in the night.

 

[Samd]

Good info. Feels a bit like an advertorial though. :?

 

[steelzhu]

Good info. Feels a bit like an advertorial though. :?

I find many interesting threads in this forums. Special equipments and excellent DIY products.
Sometime I can get some new products from the factory and show to you. Any feedback or suggestion is helpful to me.
amberwolf , Jeremy Harris, teklektik and so on had given me many good suggestion and ideas in the thread "Convert a double-motorized wheel electrical bike".
Thanks a lot