Flywheel Weights

[trapezeartist]

I've not yet opened the flywheel cover of my 2021 Race, even though I've had the bike for over 2 years. However, looking at the instructional videos on the EM website, it looks like the flywheel has 2 extra discs held by a ring of 6 screws. Am I right? Has anyone here tried removing the weights? As I don't use the clutch I'm thinking that I don't need the flywheel for winding up inertia before dumping the clutch. Instead I think I may get a little bit more snap for lifting over logs if the flywheel is lighter.

[teamferret]

I wouldn't bother. From experience the weight is more suited to none clutch use as it prevents the engine stalling. When I firtted the electronis ignition to my greeves trials bike, I left the weight off thinking being used to riding bikes with virtually none I would be fine, but it was almost unrideable. I was gutted to have to add over a kilo of weight to the bike as I've spent a lot of time and effort reducing it's overall mass

[lemur]

Personally I found the EM Race clutch provided little to no feedback through the lever, the bike has a propensity to spin the rear wheel and my first thought after riding one was they are geared too low at the rear sprocket.  I think if you made the already powerful motor spin up more rapid you will lose any benefit to additional wheel spin.

... most dangerous feature ever is the tick-over setting, if your throttle sticks (and that can happen) it will launch you.

Edited July 23, 2023 by lemur
spellink

[trapezeartist]

On 7/23/2023 at 10:54 AM, teamferret said:

I wouldn't bother. From experience the weight is more suited to none clutch use as it prevents the engine stalling. When I firtted the electronis ignition to my greeves trials bike, I left the weight off thinking being used to riding bikes with virtually none I would be fine, but it was almost unrideable. I was gutted to have to add over a kilo of weight to the bike as I've spent a lot of time and effort reducing it's overall mass

Electric bikes don't stall though.

[trapezeartist]

On 7/23/2023 at 2:00 PM, lemur said:

Personally I found the EM Race clutch provided little to no feedback through the lever, the bike has a propensity to spin the rear wheel and my first thought after riding one was they are geared too low at the rear sprocket.  I think if you made the already powerful motor spin up more rapid you will lose any benefit to additional wheel spin.

... most dangerous feature ever is the tick-over setting, if your throttle sticks (and that can happen) it will launch you.

I don't understand your tickover comment. If the throttle sticks, the engine is going to run at the speed/torque of the throttle opening regardless of tickover. Every petrol bike runs with a tickover without apparent problems. Notwithstanding, my bike doesn't have TKO and I can't see what benefit it would give me. I think it's just there to help woo petrol bike owners over to EM.

[lemur]

54 minutes ago, trapezeartist said:

I don't understand your tickover comment. If the throttle sticks, the engine is going to run at the speed/torque of the throttle opening regardless of tickover. Every petrol bike runs with a tickover without apparent problems. Notwithstanding, my bike doesn't have TKO and I can't see what benefit it would give me. I think it's just there to help woo petrol bike owners over to EM.

Have you tried the tick-over setting on the EM?  It intentionally makes the throttle hang after you shut the throttle down.  If the throttle grip hangs then you have a whole bunch of silent engine revs happening and the only thing stopping it from hooking up is the clutch.  If it were not for the clutch I would have been launched into a rock outcrop.  I only needed to experience that once to know I would never be using that setting ever again.  

[konrad]

Lemur, I will provide a counterpoint to your comments about TKO.  I have not ridden a bike with TKO, but skilled competitors who have told me it's a game-changer. 

TKO is no more dangerous on an electric bike than any traditional ICE bike (with the exception of a child's bike having a centrifugal clutch).

I see two immediate benefits: improved gyroscopic stability (improved static balancing) and a reduction in lag time when the throttle is applied.  One disadvantage is increased power consumption.

If anything, the ePure Race is geared too tall.  Considering driving force at the rear wheel, it's similar to riding a powerful ICE bike in 3rd gear.

The clutch itself is the same diaphragm type used on other trials bikes.  Perhaps you can adjust the lever more to your liking?  Choice of clutch/primary gear fluid has an effect on engagement feel.

Trapezeartist, learning to use the clutch well is an important part of modern (non-vintage) trials.

[lemur]

Lets just say, I hope nobody ever experiences a stuck throttle on an EM and if they do I hope they maintain control over the clutch, the computer doesn't have control over the motor speed and ideal would be you have a tether kill switch to shut it down before take off.  Unlike an ICE motorcycle where if your throttle sticks there will be 4 guys trying to help you kill it because they all know what a stuck throttle sounds like.

[konrad]

A stuck throttle is a safety concern on all motorcycles.  The photo illustrates three things I do to pretty much all my bikes.

White plastic "doughnut" between grip and throttle housing.  Grip cut well back so as not to interfere with my very robust homemade bar-end slider. 

And a fourth: there's a dry graphite-based lubricant between the bar and the throttle tube.  And even a fifth: frequent testing to assure easy self-closing action.

[lemur]

Do you have a tether kill switch?

[konrad]

Nope, and I'll admit I'm stupid for not having one. 

[trapezeartist]

20 hours ago, lemur said:

Do you have a tether kill switch?

All ePures have them. I don't know about older bikes.

[lemur]

On 7/26/2023 at 7:18 AM, trapezeartist said:

All ePures have them. I don't know about older bikes.

Wise move, I'd put it on the throttle side so you don't need to release the clutch to pull the rip cord.

[bikerpet]

I can't comment on the E-Pure directly but I've got decent experience with e-trials with clutch, various weight flywheels and tickover.

If you're set on not using clutch then I'd say go for it, take off the weights. It should make throttle response snappier.
The trade off is that you'll also have less drive inertia to carry up banks and steps so you often have to maintain a trailing throttle to complete the climbs, that demands some fairly sensitive throttle control. On e-bikes any throttle application has the disadvantage that if the wheel slips, even a little, then it tends to instantly spin up.

Tickover is totally pointless if you're not using clutch, in fact I think it is a disadvantage.
However ... if you use the clutch at all then it's a game changer. It is way, way harder to coordinate going from zero revs to "enough" revs for effective slow speed creeping. Most e-bikes have a slightly slower response spinning up from zero rpm - it's tiny, but combined with the added delay of adding throttle to get it started it is really noticeable and frustrating.

If you're using clutch for any accelerating maneuvers then tickover and a heavy flywheel are absolutely mandatory.
My observation of the EM is that it has far too high a gear and too little flywheel inertia for really effective launch off clutch. I'm not talking huge splats, even relatively modest ride-up and zaps are let down by the lack of effect.
As Konrad said, it's like riding an ICE bike in 3rd (or more like 4th really) gear all the time. Try measuring what gear gives you 60kmh top speed on your ICE bike then try riding sections in that gear. Electric bikes get away with it because they don't stall and they've buckets of torque at low RPM, but it doesn't make it equivalent to using a lower gear.

Stuck throttle is stuck throttle whatever the engine. It's always likely to end badly.

[trapezeartist]

I tried the no-weights version today in the rain, with the sections getting slipperier with every lap. No problems with traction but it was certainly easier to lift the front wheel (old non-athletic rider on green map). Hopefully I can try it again in drier conditions before finally making up my mind.