Full-Sized E-Trials

[heffergm]

Not to get too negative about it, but WOW is that thing ugly.

[gwhy]

Not to get too negative about it, but WOW is that thing ugly.

I guess your referring to the free-rider ? and not the trex :-)

[gasgasconvert]

I usually ride the bike for about 1 hour before I can detect any power loss, which means its done. I could add more battery capacity but I really like the light weight and my old body is pretty hammered after 1 hour. anyways.

I've built a lot of electrics, cars, bikes, trucks, etc and the first question is ALWAYS how long will it run. And there is never an easy answer because,just like a gas engine, it depends a lot on how hard you ride. But for me anyways, the run time is more than adequate, but I don't compete. There are other issues that would need to be addressed if one wanted to run with the big dogs. But as you all know, there is a big gap between just riding for fun in your back yard VS a pro event. For instance, I did not concern myself with water issues. The motor is quite exposed which helps with air cooling but would certainly have issues in competition.

When I look at the designs done by Scorpa and GAS GAS, they have clearly done a better job of making their electrics water (and idiot) proof.

I'll try to get a video up showing its performance. I think its pretty compelling using electrics for practice bikes. It will wheely up any hill very easily. Before I converted it, I rode it for a day and was reminded how incredibly hard it is to modulate the clutch throttle and brakes simultaneously. The electric is very easy in this regard.

[gasgasconvert]

Nostroke, thank you for the posts. I have a Gas Gas TXT 280 that I would like to convert, your many posts contain details of your conversion, would you be so kind as to recommend a basic conversion list of components? Motor, controller, batteries, etc? Thank you.

[nostroke]

The short list, as it were, is this:

1) Use a pancake style permanent magnet motor such as those made by Agni (the best), or Perm 120 (now Heinzman?), Briggs and Stratton E-Tek, or similar. I use brush motors because brushes never actually wear out and the controllers are cheaper (golf car stuff, such as Alltrax 400 amp, 60 VDC max (48 nominal). Also Sevcon, Curtis and others with similar power. You NEED 400 amps or it will be anemic.

2) You should try to direct drive from motor to rear sprocket if possible to get proper gearing, which depends on the motor's voltage constant (kV). Other wise, you may need a stage of reduction gearing, which means a belt or gearset. Both are heavy and prone to reliability issues if not done properly.

3) You have to come up with your own battery and BMS and charger. No simple task but do-able on the Interwebs. The pack should be able to discharge at least 400 amps for brief glorious periods of say 5 seconds. In other words, this is an intermittent, not continuous requirement. Same with the motor, in terms of thermal issues. If this bothers you, you will need a water cooled motor and fan cooled batteries, but I don't see a need for either in this application.

4) Magura and Domino both make twist grips for this application and they both kinda suck IMHO but they work fine most people, a bit twitchy control-wise though, as they are 1/4 turn..

There's more......

[gwhy]

The short list, as it were, is this:

1) Use a pancake style permanent magnet motor such as those made by Agni (the best), or Perm 120 (now Heinzman?), Briggs and Stratton E-Tek, or similar. I use brush motors because brushes never actually wear out and the controllers are cheaper (golf car stuff, such as Alltrax 400 amp, 60 VDC max (48 nominal). Also Sevcon, Curtis and others with similar power. You NEED 400 amps or it will be anemic.

2) You should try to direct drive from motor to rear sprocket if possible to get proper gearing, which depends on the motor's voltage constant (kV). Other wise, you may need a stage of reduction gearing, which means a belt or gearset. Both are heavy and prone to reliability issues if not done properly.

3) You have to come up with your own battery and BMS and charger. No simple task but do-able on the Interwebs. The pack should be able to discharge at least 400 amps for brief glorious periods of say 5 seconds. In other words, this is an intermittent, not continuous requirement. Same with the motor, in terms of thermal issues. If this bothers you, you will need a water cooled motor and fan cooled batteries, but I don't see a need for either in this application.

4) Magura and Domino both make twist grips for this application and they both kinda suck IMHO but they work fine most people, a bit twitchy control-wise though, as they are 1/4 turn..

There's more......

Just a couple of points :-)

Brushed motors are heavier and bigger compared to equivalent power of brushless (and normally a lot more expensive). Direct drive the the rear wheel from the motor is a very easy way to do it but there are more advantages in gearing the motor down before driving the rear wheel and the extra weight is worth it , you will still be lower weight than a brushed motor ).. the current that a controller needs to be able to deliver is also different on a brushless system , you adjust your required top speed go gain the torque you require and this also lowers the current needed ( this is far more complicated than this but this is the general idea..)

If I was building a conversion then I would go brushless all the way as it will work out cheaper in the long run, less maintainance, lighter and smaller .

( lighter and smaller is always good on a trials bike )

Magura and domino pot throttle are expensive and are both not to good for this application ( some will disagree with this ,,) stick with a hall type throttle or better still you can get a hall conversion that so you can use any normal cable throttle you like.

[nostroke]

Well, as usual, we can agree to disagree on several of these points. So much of this is subjective and we, silly humans that we are, tend to think that whatever we have done successfully is the way to go. The bottom line is that both GWHY and myself have built electric trials bikes that we really like. Building your own stuff, while daunting to most people, is extremely rewarding. I hate brushless motors, he loves 'em. I say tomAto, you say tomAHto.......

I still ride mine almost daily. Its a source of both pain and inspiration.

BTW, GWHY, where did you find the hall throttle? I have a friend with a electric bike rental track in the UK and he goes thru both brands of throttle pots like crazy...would love a non-contact hall device but never saw anything commercially available.

[gwhy]

:-) , I have used both types of systems and have hard data to support my claims but I do understand and agree that a brush less system can be much harder to get tuned in and is not always plain sailing. I make and sell coversion boxes for using regular cable throttles (they are my own design). I have also seen a similar device online that sells ebike stuff in China but don't know of anyone that has one from China. If you would like more info then drop me a pm.

[borus]

Well, as usual, we can agree to disagree on several of these points. So much of this is subjective and we, silly humans that we are, tend to think that whatever we have done successfully is the way to go. The bottom line is that both GWHY and myself have built electric trials bikes that we really like. Building your own stuff, while daunting to most people, is extremely rewarding. I hate brushless motors, he loves 'em. I say tomAto, you say tomAHto.......

I still ride mine almost daily. Its a source of both pain and inspiration.

BTW, GWHY, where did you find the hall throttle? I have a friend with a electric bike rental track in the UK and he goes thru both brands of throttle pots like crazy...would love a non-contact hall device but never saw anything commercially available.

Hi Nostroke, have you had a go on the EM?

[nostroke]

No but I would really like to ride one.

There is some personal history for me involved. Somewhere back in ~2003, my fledgling electric motorcycle company, ElectricMoto, was going to build bikes (The Blade) in France, at the Scorpa facility in Ailes. That whole idea never really panned out for several reasons but part of the deal was that I was to show the guys at Scorpa some of the electric propulsion basics. So I hooked them up with motor batteries and controllers from our Blades that we made there and one of their R&D guys packaged one into their trials chassis during the three weeks that I was there in France. It was pretty cool.

Fast forward about 10 years, Phillipe Arresten (SP?), who was CEO of Scorpa at the time, starts EM, making electric trials bikes! And it looks really nice. So yeah, I want to ride one big time!

[slip_kid]

It been over a year, are there any updates worth mentioning?

Great thread, thanks to all who contributed.

[Andy]

It been over a year, are there any updates worth mentioning?

Great thread, thanks to all who contributed.

 

EM have a presence at the World Championship riding the 125/International route. There were a couple in Andorra last weekend and another two here in Lourdes this weekend. If/when it gets to three riders then there will be a podium specifically for electric bikes.

 

They can't half nip on, but are a bugger to photograph because you can't hear them rev to prep yourself like you can with trad bikes.

 

 

[crazybond700]

New regulations: the trials riders must shout ''broap'' on photogenetic spots

[nostroke]

Ha. Personally, I'm waiting for a class for Nostrokes......

 

[nostroke]

 

I've added some capacity to my bike recently. Before I had a 14S 2P quick swap battery, using 10 AH Li cobalt pouch cells. Now I have a 14S 1P pack made from 27AH cells, same chemistry. So my capacity went up from 20 AH to 27 AH, or from 1.036 kWh to 1.398 kWh. Nearly a third more runtime. But they don't quite deliver the current as aggressively as the 2P pack. The chemistry is not quite as hot.

Edited June 30, 2016 by nostroke