GNG mid drive Trials bike build

[Denisesewa]

I set up the 2 speed switch with GWHY's recomended settings of 60% and 100% , what a nice difference , on the low setting the bike is way more comfortable to ride and still has way more torque than stock, as has been suggested the controller tends to soften the throttle in this mode, still feels the same in high setting so for me I think low setting will be " normal" riding with the high setting for intergalactic warp drive.
I am a bit surprised that this along with cutting down the throttle tube has improved things this much, I used a micro toggle switch mounted to a modified Avid/SRAM Matchmaker, its within easy reach and effortless to use.

 

[Denisesewa]

BTW, I used the info in this artical to mod the controller for the switch although I only used the X1.

http://zenid10.wordpress.com/category/4-how-to-guide/4-5-other-modifications/4-5-6-installing-a-speed-control-switch/

 

[gwhy!1]

please it worked out for you... now get some practise in and get some vids sorted out

 

[Denisesewa]

please it worked out for you... now get some practise in and get some vids sorted out

Yes Sir Captain!!

 

[FfredDRredD]

It sure is kool a girl(nothin against girls i lov em) can build a bike like that and ride it, the girls i know are girlie girls that would'nt try anything like that AND build way better bike than mine. Nice work

 

[Denisesewa]

It sure is kool a girl(nothin against girls i lov em) can build a bike like that and ride it, the girls i know are girlie girls that would'nt try anything like that AND build way better bike than mine. Nice work

Thanks ! but 56 years old doesn't exactly qualify as a girl, always been a gearhead.

 

[recumpence]

It sure is kool a girl(nothin against girls i lov em) can build a bike like that and ride it, the girls i know are girlie girls that would'nt try anything like that AND build way better bike than mine. Nice work

Thanks ! but 56 years old doesn't exactly qualify as a girl, always been a gearhead.

Well, 56 years old doesn't make you a guy. :wink:

Matt

 

[Denisesewa]

Out for a ride today, too bad the vid doesn't show just how steep some of the climbs are.
Kinda crap raw vid but the ride was fun.

http://www.youtube.com/watch?v=HQSFbLXzsNo

 

[Whiplash]

Awesome trail! Looks like some of ours but you have to travel a bit to get to mine from the city..

 

[christerljung]

That ride looks absolutely fantastic! Very low noise from the chain!?

I got the trottle-mod sorted out btw. The response get spread out over the whole twist with the help of two resistors. Gonna post a vid and instructions in the GNG-thread tommorrow.

 

[Denisesewa]

That ride looks absolutely fantastic! Very low noise from the chain!?

I got the trottle-mod sorted out btw. The response get spread out over the whole twist with the help of two resistors. Gonna post a vid and instructions in the GNG-thread tommorrow.

Cool , I was just researching different throttles, I'll be reading your post with alot of interest.
Yes, the 25 chain is very quiet, getting the runout to a minimum and the chain the right length I think is the secret.

 

[LightningRods]

I got the trottle-mod sorted out btw. The response get spread out over the whole twist with the help of two resistors. Gonna post a vid and instructions in the GNG-thread tommorrow.

Waiting for this post with great interest, Christer!

 

[teklektik]

I installed the Lyen 12 FET controller, at its present settings the bike is scary, throttle control is almost non exsistant,...

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

As mentioned in the GNG/$400 thread, there are similarilies between your rig and a geared hub motor. A recommended phase:rated current ratio for DDs is around 2.5:1 and that is probably what your out-of-box controller settings reflect. However, MAC/BMC motors perform nicely with a ratio more like 2:1. Here the trick is that rated (battery) current effects the entire rpm range whereas phase (motor) current has only low speed effect. So - a higher rated current will get a broad power improvement, but a lower current ratio (reducing the phase current), will reduce the available low end power.

I have BMCs, not a GNG, (that means this is a guess ) but I'm thinking you might try tinkering the current ratios a bit to marginally assist with your twitchy low end throttle - nothing ill can come of it if the experiment is ineffective.

I'm guessing your controller is set at something like 30A:80A (2.6:1) right now. So you might experiment by first turning down your phase amps to reduce the power at the low end (easier to control) - maybe something more like 30A:75A or so. If this seems too wimpy, you might possibly raise the rated amps to pick up some lost power across the board - having a larger effect at higher rpms where the reduced phase amps are not in play. For instance - you might jack up your rated current to 36A and using the 2:1 ratio, drop your phase current to 36A x 2 = 72A. Just illustrative values but you get the drift... The ratios are just rules of thumb, so you can fiddle a bit e.g. 36A:74A is more than 2:1 but it may give you what you want.

 

[Denisesewa]

I installed the Lyen 12 FET controller, at its present settings the bike is scary, throttle control is almost non exsistant,...

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

As mentioned in the GNG/$400 thread, there are similarilies between your rig and a geared hub motor. A recommended phase:rated current ratio for DDs is around 2.5:1 and that is probably what your out-of-box controller settings reflect. However, MAC/BMC motors perform nicely with a ratio more like 2:1. Here the trick is that rated (battery) current effects the entire rpm range whereas phase (motor) current has only low speed effect. So - a higher rated current will get a broad power improvement, but a lower current ratio (reducing the phase current), will reduce the available low end power.

I have BMCs, not a GNG, (that means this is a guess ) but I'm thinking you might try tinkering the current ratios a bit to marginally assist with your twitchy low end throttle - nothing ill can come of it if the experiment is ineffective.

I'm guessing your controller is set at something like 30A:80A (2.6:1) right now. So you might experiment by first turning down your phase amps to reduce the power at the low end (easier to control) - maybe something more like 30A:75A or so. If this seems too wimpy, you might possibly raise the rated amps to pick up some lost power across the board - having a larger effect at higher rpms where the reduced phase amps are not in play. For instance - you might jack up your rated current to 36A and using the 2:1 ratio, drop your phase current to 36A x 2 = 72A. Just illustrative values but you get the drift... The ratios are just rules of thumb, so you can fiddle a bit e.g. 36A:74A is more than 2:1 but it may give you what you want.

Thank you for that, I will be experimenting !

 

[teklektik]

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,

My knee-jerk reaction is to spring for a CA V3 to get

• adjustments to match your throttle/controller voltage ranges (instead of the classic resistor/trimpot approach)
• throttle ramping (to moderate get-away power)
• closed-loop current throttle for direct mapping of 0-100% throttle voltage to 0-100% controller rated current (refined control)
• three selectable presets (groups of configuration settings - e.g. trail mode/street mode/loaner mode)

There's no manual for it yet, but here's a post on setting it up that will show a lot of the configuration options and operating modes (follow in-line links for details).

It's still in beta, but the present firmware works well. V3 = Highly recommended.

 

[melodious]

We now have a few solutions to change how the throttle input responds for a trials bike setup. It seems the simplest is via a CA v3, though it's probably the more expensive route. Another route is using resistors which requires physically opening the electric throttle mechanism and soldering them inline; moreover, this mod only works for a specific type of throttle*. Also, using various 2 or 3 speed switches to remove the "twitchy" nature of these throttles.

Without having someone here to physically make different throttle setups, I'm sure some of us just have a professional "feel" how each of the throttles will behave. My question is, which is the best solution for this type of riding So if/when we make one of these fun machines, we have a handy guide to get us there. The turnkey electric trials manufacturers (Gas Gas, KTM, Oset, etc.) probably already have addressed and solved this issue.

 

[Denisesewa]

We now have a few solutions to change how the throttle input responds for a trials bike setup. It seems the simplest is via a CA v3, though it's probably the more expensive route. Another route is using resistors which requires physically opening the electric throttle mechanism and soldering them inline; moreover, this mod only works for a specific type of throttle*. Also, using various 2 or 3 speed switches to remove the "twitchy" nature of these throttles.

Without having someone here to physically make different throttle setups, I'm sure some of us just have a professional "feel" how each of the throttles will behave. My question is, which is the best solution for this type of riding So if/when we make one of these fun machines, we have a handy guide to get us there. The turnkey electric trials manufacturers (Gas Gas, KTM, Oset, etc.) probably already have addressed and solved this issue.

I suppose it also depends on what type controller you have, mine is programable and as has been stated there are various parameters which can be changed such as turning down the phase current and upping the rated current to compensate , I have not yet experimented with this but I will, I also found a super deal on Magura throttles and decided to give one a try and mod it mechanicaly as has been documented elswhere on the forums, I really liked the Magura on my brushed MX bike, we'll see.
So if anyone wants a magura go to Holmes hobbies, sign up for an account and during checkout type the word " shipping " in the coupon code box, you'll get a Magura for just over $40 shipped( at least in the USA).
I am pretty happy so far with just cutting the throttle tube down to about an inch and putting in a 2 speed switch with 60% and 100% settings, the cut down tube allows alot more control in tech sections especially when using the front brake alot but takes some getting used to, once the dead spots in the throttle are taken care of I think I'll be satisfied.
I started another trials build yesterday mostly just to keep occupied during the winter and use up some bike parts, I'll start another build thread on that one later.

 

[teklektik]

So if anyone wants a magura go to Holmes hobbies, ...

Wow - Thanks for the tip on Maguras - excellent price! Another goodie into the Next Build Box...
I have one on my bike with a V3 - remarkable control. I can putter along at 60W as easily as 3kW.

 

[Cyclebutt]

Excellent build, denisesewa! Just wondering how the primary chain drive is holding up. Would love to see a thread devoted to GNG primary drive modifications. There are many here, but all scattered about. Some have machined the pulleys off, I think some have found other ways to remove them (unscrew?, Pull?), what did you do? Thanks!

 

[Denisesewa]

Excellent build, denisesewa! Just wondering how the primary chain drive is holding up. Would love to see a thread devoted to GNG primary drive modifications. There are many here, but all scattered about. Some have machined the pulleys off, I think some have found other ways to remove them (unscrew?, Pull?), what did you do? Thanks!

Back on page 52 of the main GNG thread I posted some info on how to do the chain mod, you have to click on the pics to get the video to play, It has been verified that the engine pully is part of the shaft and not removable so the options are to machine a new shaft or mill down the original shaft which isnt hard to do if you have patience, all I used was a new file and digital calipers with the motor spinning at a fairly slow RPM. Topic starts here >> http://endless-sphere.com/forums/viewtopic.php?f=28&t=42785&start=765
The #25 chain seems to be holding up just fine as does Christerljung's set up with #25, since its double reduction with a High RPM motor the pimary doesnt seem to get stressed that much, the key to success is to get the runout of the sprocket to a minimum, I made a bushing to center the sprocket on the original pulley( after cutting off the outer flange) and kept adjusting to get minimal runout then used hotmelt glue to fix to two together so I could remove and drill the mounting holes without things moving, I am about to take delivery of my second kit and the parts to convert it to chain, Perhaps I'll try to do a step by step if there is interest.

 

[Cyclebutt]

Thank you so much. I started a new thread if you would like to contribute.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=46738

Love the carbon work and will have a close look at your primary drive mod, thanks!

 

[Denisesewa]

Teklektic wrote "
I'm guessing your controller is set at something like 30A:80A (2.6:1) right now. So you might experiment by first turning down your phase amps to reduce the power at the low end (easier to control) - maybe something more like 30A:75A or so. If this seems too wimpy, you might possibly raise the rated amps to pick up some lost power across the board - having a larger effect at higher rpms where the reduced phase amps are not in play. For instance - you might jack up your rated current to 36A and using the 2:1 ratio, drop your phase current to 36A x 2 = 72A. Just illustrative values but you get the drift... The ratios are just rules of thumb, so you can fiddle a bit e.g. 36A:74A is more than 2:1 but it may give you what you want. [/quote]
I finally got around to resetting some controller parameters, still experimenting but the block time was 10 and is now .01, dropped phase amps to 74 from 80 and upped rated amps to 32 from 30, with the 60% low setting on the 2 speed switch the throttle is very controllable now ( still has the lowend dead spot) its still a bit touchy on 100% but much better,after over an hour the motor is just warm to the touch ( 44F degree air temp) I recieved the Magura throttle today and will install it when I get a snow day, hopefully that will be the final touch.
Anyway, got out for an hour + ride today in really rough terain and had a blast , everytime I try climbing up something I dont think the bike will make it surprises me by proving me wrong.
Thanks Teklektic !!