GNG mid drive Trials bike build

[Whiplash]

Parts loosely assembled , still need buffing, the pics dont do the carbon justice but you get the idea, I cant do final assembly untill I recieve the new controller since its a bit bigger and I may need to change some things to get it to fit.
Kinda thinking about doing the seat in carbon as well but that might be overkill?

Unbelievably cool! I would definitely do the seat in carbon to match! That's the best looking trials build to date! Should be really fun! I would love to do something similar with rear suspension for trail riding out here! I have some awesome goat! trails and my current bike with the MAC mid mounted climbs effortlessly but is a bit tall in the center for the really slow technical stuff. Yours would be great!

 

[Denisesewa]

[
Unbelievably cool! I would definitely do the seat in carbon to match! That's the best looking trials build to date! Should be really fun! I would love to do something similar with rear suspension for trail riding out here! I have some awesome goat! trails and my current bike with the MAC mid mounted climbs effortlessly but is a bit tall in the center for the really slow technical stuff. Yours would be great!

Thanks !!
You know, you might be surprized at how little rear suspension benifits you unless you are doing some big drops, This past year I built a full rigid 29er and found I really like the direct feedback and positive pedaling, the only time I miss suspension on my favorite fast trails has been when there are stutter bumps in fast sweeping turns and occasionaly in big rock gardens, I still ride full suspension on the ski slopes though.
Being hardtail has greatly simplified this build and I dont think I'm giving up too much.

 

[speedmd]

Great E-plunker. Seeing your photos brings me back to my early days racing MX. I trained some off days riding through the most gnarly stuff I could find for my OSSA M.A.R.. IMO Nothing better for improving riding skills and balance on the bike. Seeing your photos brings back some good memories.

Like Everything you did. I would forget sitting and pedaling and leave the seat as is most of the time. Raising it makes it much more a safety hazard when riding the near impossible stuff but if you have to pedal home a ways, I agree it would be good to be able to raise it for that. Also I would not go below 160mm cranks. One thing you do not want to give up is Torque when riding observed trials. Most good JR road bikes have 155mm cranks you may be able to try out and see if they may work for you. Many good choices in the 160 and 165mm lengths now days.

For pegs, I would see if you can sneak in a bar that sits atop of the chain stays just in front of the rear tire. Not sure how thick/strong the stays tubes are there but they do look to be nice and deep rectangles with a few cross stiffeners also to help spread loads. You may need to s shape it a bit as the chain ring will need to be cleared.

Agree on the hard tail or near hard tail for trials. Some of the harder polymer bushing type suspensions may be interesting choices also as some suspension will allow the wheel to stay in contact and get a bit more grip at times. Agree, when all is considered and manpower is all you have, it may be best to go ridged with a bit fatter tire. You have my interest for certain. Best wishes on the development/build. mario

 

[Denisesewa]

Some more progress . I installed the Lyen 12 FET controller, at its present settings the bike is scary, throttle control is almost non exsistant, it is easily twice the power of stock and amp spikes peak at 38, still the motor is cool although it is bitter cold outside, the first little ride when I was being super careful with the throttle the bike stood straight up and left me running after it trying to catch up ! so any suggestions on taming the throttle are welcome. in this quick little vid I am being SOooo careful with the throttle. CLICK ON THE PIC FOR VID>


I also made the seat texured carbon, made a primary chainguard and installed the new tires, I have dubbed the bike " PEDATRIAL A.G.B.' (anti gravity bike) since we know downhill bikes as "Gravity bikes" it seems appropriate, also installed some graphics and tried to make my own custom graphics for the chainguard but failed bigtime. this is how that turned out.

Its supposed to look something like this, I am having a local shop make the graphics now.

Here are some more pics

Once the throttle is figured out and I get some time on it I'll try to get some footage of it doing what its supposed to do, Trails!

 

[spinningmagnets]

Great build! This has to be one of the most interesting ES bikes from 2012...

As for the throttle, I have heard that the cell_man 3-speed switch helps, but I have never used one personally.

 

[melodious]

I really think the mid drive concept really adheres the best for these trial bikes. They need more torque off the line to finesse themselves up and over into the oddest of places

Once you figure out how to get your throttle under control your set. 8)

 

[Denisesewa]

The issue I see with the throttle is that it is something like 1/8 turn from off to full, if it was 1/2 turn there wouldnt be a problem, If I knew enough I'd try to modify it but I dont.
The print shop came through with some nice work on the graphics.

 

[gwhy!1]

I love your bike ,,, top job and its got me wanting to do a trials cycle again 8)

the throttle problem is a major one that I have been battling with for ages myself, I have tried so many ways to sort it out.

a 3 speed switch is about the easiest solution but not a 100% fix : These controllers can be setup to change the resolution of the throttle via a basic switch that needs to be wired into the controller then the controller needs to be programmed with your desired settings. for me initially 2 setting was good enough a 40% and a 100%.

log throttle response was very tricky to setup but there are a couple of off the self devices that can fit inline with the throttle signal to re-map the throttle curve. I didnt get on with this at all even though it worked reasonably well and I didnt have to worry about switching a switch it just didn't do it for me ( 3 speed switch was better )

on my current project I didnt have to worry about having the rear brake on the handle bars ( its a motorcycle ) so I went about having a sort of on-the-fly battery current limiting the controller via a clutch lever and this has been the break through as regards taming the throttle and works 100%. I am told that maybe a variable phase current limit will be even better ( which I will be looking into, just for the fact that it will help the controller survive more than anything else ). but I am not sure how this can be done if not using something to adjust the limit on the fly i.e on a bicycle, but I am thinking about it. With trials it is not just a case of ramping the current up of a fixed amount of time ( which could be one way of doing it ) but the current limit needs to on demand for 100% control.

If anyone has any ideas please chip in ( Having the clutch works so its just a matter of automating that part ) , Im all ears and willing to try to find a absolute solution to this age old problem of throttle control on these very twitch bikes

 

[Denisesewa]

I love your bike ,,, top job and its got me wanting to do a trials cycle again 8)

the throttle problem is a major one that I have been battling with for ages myself, I have tried so many ways to sort it out.

If anyone has any ideas please chip in ( Having the clutch works so its just a matter of automating that part ) , Im all ears and willing to try to find a absolute solution to this age old problem of throttle control on these very twitch bikes

I have read alot of your posts on your trials motorcycle build and your clutch in particular, I am impressed with your results although most of those discussions go over my head almost immediately , I really dont like the idea of a 3 speed switch although my new controller is programable for it. I did post on the general forums for info on modifying the twist throttle to something more like half twist which I think would at least help once your moving. kinda bummed that this problem is keeping my bike from being trialable, as you well know, control is everything.

 

[Denisesewa]

BTW Gwhy
wouldnt a left hand thumb shifter incorporated into your clutch system rather than a standard lever be a viable option? I know I have no problem operating a thumb throttle and brake lever at the same time. Just a thought.
"D"

 

[melodious]

Maybe PM Jeremy Harris about your controller issue. He's the first person that came to mind when it comes to an electronics Jedi master. I wish I could fathom 10% of the stuff he puts here. One day, it will just click in my head and I'll have that "aha!" moment. :lol:

Sigh, we have motors that can put out Kvolts of rotation, and batteries that can supply it, but we just need a controller that isn't a glorified on/off switch. :?

 

[gwhy!1]

a thumb shifter may work it depends on the user, I think it will take a bit of getting used to. I made my own throttle that also allows a proper twist action ( it has more travel ) about a extra 10-15 degrees maybe.



this was basically the setup ( it has changed a little since the picture , it now has a spring on each post it make it far more constant )


it is a really easy setup, it just uses a 1 hall sensor and 2 magnets.


the clutch arrangement on my bike also uses this method.

 

[teklektik]

This post by Justin has a brief discussion of non-linearity issues with hall throttles and an interesting approach using a different type of magnet.

 

[Denisesewa]

The temps got above freezing so I took the bike out for its first real ride, I rode one of my favorite MTB trials which right now is snowy, a bit muddy and pretty technical, there are steep drop in/climb out gullies and some steep climbs with loose shale which on my MTB on a good day I can only make about 1/4 of and this thing just ate it up! I cut the throttle tube down to just over an inch and that helped with control, once the voltage got down around 55 volts I found it much easier, either that or I am getting used to it. super easy to lift the front over obsticles and it never slowed on the climbs enough to use pedal assist.
I feel this bike has about the same low speed ability as my old TL125 had at about 1/4 the weight and I never used low gear, very nimble and responsive, I knew the frame geometry was great on this bike which is why I chose it but really didnt expect it to be this good under power, I feel no loss of performance for lack of rear suspension although I only did a couple small jumps due to the snow and ice landings, I am running a 24x3.00 rear tire at 16 psi. motor was just warm enough to feel after about 30 minutes and my fingers were going numb so that was enough.
I have a few things to upgrade, adjust or change but boy am I glad I put the effort into this build and couldnt be happier with the result.
Now I have an afternoon of cleaning the muck off, does anyone just wash their E-bikes? seems like it might be a bad idea to me so I'm thinking a bucket of warm soapy water with a brush and sponge.
8) <<< One happy camper !!!

 

[christerljung]

That sounds so great! Congratulations to a fantastic build! That chaincover is a piece of art. Some years ago i was building my own surfboards with similar technique and it was not an easy task at all.
How many cells is series? 15?
Have you tried the phase-current limit adjusting possibility in the controller software?
I´m looking into that right now.
(But im also gonna open up the throttle to see if something mechanical could help it calm down.)

Hope you get rid of the snow. We got 40cm here now.
Just bought spiketyres for my kona stinky build.

 

[gwhy!1]

turning the Phase current limiting down will help a little but it become a fixed limit and this will reduce the overall torque of the motor so it depends what sort of performance you want from the setup , You need a on-the-fly limit or a current limit that is tied into the speed based throttle some how. There are things you can do to get the full range or better control from the hall/pot throttles i.e shifting the start point of the twist , log throttle curve or 2/3 position throttle resolution switch,

 

[christerljung]

There is another way also maybe. Thru the CA it is possible to let the throttle just give position input. Then the CA outputs the signal in some different manner, remapped? I dont know exactly, but it might help?
After reading alot of posts regarding throttle charcteristic i am a bit suprised no one yet have the final solution.

 

[Whiplash]

What about wiring in a button rather than a switch that give you your normal power all the time and then you can simply hold the button with your left thumb when you want the big burst of power? You can get really low profile flat push type switches that could even go UNDER your left grip so you just squeeze for more power! I LOVE your bike! I just got a new TIG welder coming and will be doing a custom frame just like yours from aluminum as soon as I get it for my own design "Trail Drive" made from a MAC motor running 2000 watts so it should be great fun! Again, thanks for the inspiration!

 

[Denisesewa]

What about wiring in a button rather than a switch that give you your normal power all the time and then you can simply hold the button with your left thumb when you want the big burst of power? You can get really low profile flat push type switches that could even go UNDER your left grip so you just squeeze for more power! I LOVE your bike! I just got a new TIG welder coming and will be doing a custom frame just like yours from aluminum as soon as I get it for my own design "Trail Drive" made from a MAC motor running 2000 watts so it should be great fun! Again, thanks for the inspiration!

I am thinking about the options for a 2 speed switch and will be working on that today, a push button may be a viable option, I think I'll wire it up so I can quickly change switch types to experiment.
Once you start a build thread for your bike please post a link here, I'd like to follow along on your build, I'd love to get a TIG but its hard to justify, Sure would have been nice to design the frame around the battery compartment.

 

[Denisesewa]

That sounds so great! Congratulations to a fantastic build! That chaincover is a piece of art. Some years ago i was building my own surfboards with similar technique and it was not an easy task at all.
How many cells is series? 15?
Have you tried the phase-current limit adjusting possibility in the controller software?
I´m looking into that right now.
(But im also gonna open up the throttle to see if something mechanical could help it calm down.)

Hope you get rid of the snow. We got 40cm here now.
Just bought spiketyres for my kona stinky build.

I am running 14 cells in series x 2 parallel ,, I'd really like to see pics of the inside of that throttle but what I've read its not easily modified, I am thinking about buying that Wuxing throttle which has the curved linier magnet.

 

[christerljung]

Is that curved magnet on every throttle they sell? Can´t find anything about a curved magnet on their ali-site:
http://jdwx.en.alibaba.com/

 

[gwhy!1]

What about wiring in a button rather than a switch that give you your normal power all the time and then you can simply hold the button with your left thumb when you want the big burst of power? You can get really low profile flat push type switches that could even go UNDER your left grip so you just squeeze for more power! I LOVE your bike! I just got a new TIG welder coming and will be doing a custom frame just like yours from aluminum as soon as I get it for my own design "Trail Drive" made from a MAC motor running 2000 watts so it should be great fun! Again, thanks for the inspiration!

I had a 3 position motorcycle light switch that I used that also had the horn button on, and I used the horn button to override the switch position i.e give 100% when pressed but I found it actually better if it was the other way round i.e when pressed cut the throttle down to 40% . The 3 postion switch was wired as, 0%(off)-60%-100% , this was the best setup if using switches ( in my option ).

 

[Denisesewa]

Is that curved magnet on every throttle they sell? Can´t find anything about a curved magnet on their ali-site:
http://jdwx.en.alibaba.com/

Unfortunatly I couldnt find out if they all have it or not either, luckily they are cheap so not too much to lose.

 

[Denisesewa]

What about wiring in a button rather than a switch that give you your normal power all the time and then you can simply hold the button with your left thumb when you want the big burst of power? You can get really low profile flat push type switches that could even go UNDER your left grip so you just squeeze for more power! I LOVE your bike! I just got a new TIG welder coming and will be doing a custom frame just like yours from aluminum as soon as I get it for my own design "Trail Drive" made from a MAC motor running 2000 watts so it should be great fun! Again, thanks for the inspiration!

I had a 3 position motorcycle light switch that I used that also had the horn button on, and I used the horn button to override the switch position i.e give 100% when pressed but I found it actually better if it was the other way round i.e when pressed cut the throttle down to 40% . The 3 postion switch was wired as, 0%(off)-60%-100% , this was the best setup if using switches ( in my option ).

I think I am just going to go with a 2 position and use your suggestion of 60% and 100% , for my bike I dont see a use for a off position since it has freewheels and as soon as you back off the throttle even a little it coasts so there is no power being put to the ground, I think it would be a little un-nerving to apply throttle and use the switch as a clutch since there is no motor RPM noise like in a gas powered trials bike, you wouldnt know what power level you are going to get.
I can see already that riding an electric trials bike is going to take an entirely different style of riding.

 

[gwhy!1]

I think it would be a little un-nerving to apply throttle and use the switch as a clutch since there is no motor RPM noise like in a gas powered trials bike, you wouldnt know what power level you are going to get.

your not wrong but it did make it very interesting when other people had a go on it even just the 2 postions was intresting if you forget to zero he throttle before you switched from 60% -100% . The momentary button to give only give 40% was quite usefull e.g if you needed max for a climb that require some technical stuff straight after the climb it was easier to just push the button rather than trying to use the switch when you need to be on the ball.

the on-off position was more to with a safety thing , should the throttle go wrong .