nostroke

I was just digging thru old posts and saw a discussion we electric geeks had in 2013 with some interesting stuff in it. Now, 12 years down the road, I recently bought a 2024 EM Pure Sport. It has an awesome diaphragm style one finger hydraulic clutch. I'm learning why its important to mechanically decouple the motor for rapid stops and starts. And I love this bike. But I'm still hankering for a sound synthesizer. The gear whine of the EM isn't loud enough for good aural feedback of RPM which is sort of critical with this grabby clutch. I posted this previously (above this post) but surprised that after 2 weeks and over 1k views no one seems to have any opinion one way or the other. But it seems like such a natural improvement for electric trials, am I wrong?

I want my 2024 sport to sound like Toni's 4 stroke torquer since I've been inundated with his impossible antics on Instagram. I love the one finger diaphragm clutch but to really get the feel of motor /flywheel inertia, I want a low frequency pop instead of the 'zing' sound which is mainly due to gear train noise. So I took a cheap 12VDC car alarm out of the trash and tapped it across two random AC motor phase leads, just for giggles. And predictably, it first smoked a little, probably the 50+ volts into 12 V circuit thing, no surprise. But then it kept working and would produce an ugly growly sound proportional to RPM. I'm not an Electrical Engineer but no doubt someone with circuit design savvy could use this tiny phase lead signal to trigger a proper .WAV file of a single gas bike pop and make a scalable frequency output to a piezo or a speaker. Has anyone done this? I expect it could have its own little battery. Heh, maybe even BT into my hearing aids. Just dreaming but would love to hear if anyone has done anything along these lines?

Not sure if this will help but having a slightly dirty potentiometer can act like that I would think. I've used both Magura and Domino on several bikes and I don't recall that either one uses a hall effect sensor. You can observe the "dirty" signal as an erratic ohm value when tested disconnected from bike. A 0-5k pot with three wires will read about 5k ohms between two wires regardless of twisting position. The third wire is the signal where you would observe the erratic resistance across it and either of the two other wires. Its a simple metal wiper (signal) that moves across a fixed wire wound 'fixed' resistor. But it could be a hall type non-contact also used a lot. I've seen quite a few 'dirty' reading throttle pots and they usually are near the lower throttle position, likely due to more wiping at low throttle.

Oh, OK just read your link, thanks. Looks do-able but there are probably a lot of parameters that I would need from motor mfgr. Due to the lack of any serious ramp programming on this Alltrax golf cart controller I used here, I made an audio taper (log) potbox so you have great slow precision on an otherwise sketchy throttle and you get the big splat energy when you wick it open. Almost as good as a clutch overall but way easier to ride IMHO for medium skill level riders (me). Speed (voltage) mode does not have that time lag that a torque (current) mode has so response is instant. And I 'll certainly dig deeper into your experiments. Thanks for all that .

Is it likely that the controller is available direct from siliXcon unprogrammed? Also, I should add that the Perm/ Alltrax package I used, while pretty crude by today's standards, does not use a feedback device although a brushless could emulate that with its feed back loop I suppose. I'm not a EE but have dabbled with EV controls forever.

Just curious if this is possible, within reason. I have an old relationship with Phillipe at EM from 2 decades ago and am trying to rekindle that relationship for both humanitarian and access reasons.

I'm curious about some of the programming used on these bikes. I just got a 2024 pure sport with diaphragm clutch and the 3 mode settings. But I'm used to a bike I built and posted here years ago that uses a Perm brushed motor and an Alltrax 48V 400 amp controller. I am comparing the EM throttle response and general feel to my old 'Digit' I built. The Digit, because its a brushed motor, is by nature always in speed mode, so throttle command is proportional to the motor rpm as opposed to most brushless motors that typically (the EM) operate in torque mode where the throttle command is proportional to the current. My Digit does not have a clutch but throttle response is very crisp and both splats and wheelies are very predictable and easy to control. The EM however feels really mushy response-wise and its harder for me to control since I'm used to speed mode modulation. Has anyone programmed an EM to operate in speed mode? I also build street and road race electric bikes and have done so for many years (I'm old). On street bikes, torque mode is more intuitive but for off road use and on my EM, I think that speed mode would be better. Anyone know what I'm babbling about?

Hey I just got a 2024 Sport as well and am totally digging it, learning to use a clutch. The diaphragm clutch is awesome.

I'm not sure that what I have will solve your problem. My model, as I dig deeper into it, has a number of hard points that are NOT the same as the GG geometry. Mainly, I'm talking motor mount plates and various body related points. I didn't fully copy their frame, only the rake, trail, wheelbase, shock linkage etc, the critical geometry that makes it handle. So if you are converting one of their frames with adapting plates, nothing will match up.

It appears that I'll need to link you to a dropbox; the forum won't accept any CAD files. Bear with me, I'll try to get them uploaded and send you a link later. I think the Scorpa chassis would be best if I saved it as a Autocad 2D or a generic DXF. Do you ever use GrabGad? I could maybe post it there. I have no concerns about copying or ownership. Its a great resource.....

What format do you want? Its a 2013 Solidworks solid model but I can save in more generic format like STEP or IGS. Also, my model is from my own design frame which is very close to GG but I did change a few things. I also have a dimensional flat sketch of a Scorpa frame that I got from Phillipe who later started EM from back in ~2006. But the Scorpa geometry seemed weird so I didn't use it and used GG geometry that I copied from a TXT 200.

What cad format? Its in 2013 Solidworks but I can save it as STEP or IGS for you, which opens in most software.

Some people make an electronic clutch, which I also made and didn't like either. Its a potentiometer that sort of cancels the voltage from your throttle.

If it were mine, I'd definitely use some primary reduction, chain, belt, gears, whatever. That smaller motor is likely a high rpm motor and needs reduction, but I would not use a clutch without gearbox.I tried it. It sucked and added weight. Unless you are a high level rider, its just fine without a clutch once you dial into it.

Well, I hate to burst your bubble but it really doesn't work like you are expecting unless you have low first second and third gears. Also, its worth mentioning that the GG has a roughly 20 pound flywheel for inertia when you dump the clutch, the flywheel effect,, so the inertia of your smaller motor is quite small, which further reduces the 'big hit' you want.

Looks like a nice little motor. So you will use the small primary drive crankshaft gear keyed or splined to the motor shaft , then to the stock GG clutch, right? Then make a inner and outer case with the bearings for the countershaft, correct? You will need an oil seal on the inner motor shaft and on the outer countershaft. Is that the plan? I would be concerned that without a gearbox, if the motor KV and your reduction, primary and secondary combined is not low enough, dumping the clutch will be like dumping clutch in 3rd gear. Or whatever. What I'm trying to communicate is that with a fixed reduction, you have to pick a realistic top speed but if you do that, it would likely be geared too tall to have any decent clutch launch. I tried this with and was like, oh! I didn't work..... Here is my direct drive GG conversion I built before I made my own.

So I take it you intend to use the stock gearbox as well as the wet clutch? What motor are you intending to use?`

I confess there's a part of me that want to do a small production build but calmer minds prevail. Could I be , egad, getting older? Smarter? Nah....I'm staying busy babysitting this RR bike. Its faster!

Yep, I only made one but I still have tooling for all the plastics that I vacuform. The frame fixture is another story. I made a minimal one that wasn't worth using again, just to try out my frame design. I would have to make a better fixture before building more. But still, anything less than ten or so presold would not be worth the effort.

Been there and done that, sorta. In 2003, I made and sold ~ 60 MTB based electrics, no pedals, under the Denali name. And we made 6 TorkAtak electric trials bikes.. In retrospect, they fairly sucked. I snapped one in half. Since then, my current ride, Digit, is pretty awesome IMHO. I've been riding almost daily for about 5 years.I copied a lot of Gas Gas geometry but made it all from scratch from my own Solidworks model. After Denali, I built more bikes under the ElectricMoto banner, the Blade. More of an MX style using the 8" Briggs motors (eteks). I'm re building one now with some killer lithium cells I just packaged. But starting a company today is much bigger deal than just making good product.

That would certainly work. But still, I'm not really seeing that for maybe 3/4 of trials riders, that big hit from a clutch / g'box is needed. Pro level, yeah, gotta have it.

Personally, I don't quite see how a clutch would work on an electric unless you included a multi-speed g'box. I actually built one and tried it with a fixed 6 to 1 reduction. I put the clutch assy on the motor shaft, so it was between it and the countershaft sprocket. But without a really low fixed reduction, it was like dumping the clutch on a gasser in 4rth gear, ie, quite the anti-climax.

Wow. Good on Mr Kent. I hope more people figure it out. Electrics are way easier to ride trials on, hands down IMHO, clutches be damned. Lets face it, riding trials is really difficult for most. That's why more people ride MX or Enduro. Anything that makes it easier without compromising the challenging nature of the sport has got to be a good thing for the sport overall. And did I mention that you can ride them anywhere? OK, I'm raving.Thanks for the link!

Here's the 3D solid model that I used to design and build from. Done in Solidworks. Once the model is complete, fabrication is pretty easy...just copy your model!

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.