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[ZeroSinMA]

I don't see how they're going to pull of another 2x range improvement as from 2010 to 2012. I hope the focus is on improving efficiency at higher speeds, the current weak spot for the ZF9.

An electric doesn't need six speeds but a second gear will improve efficiency on the highway.



Right solution: a two speed gear box.

Simple, light weight, but some power loss due to friction.










http://grabcad.com/library/2-speed-gearbox

Wrong solution: six-speed gear box.

Unnecessary complexity, weight, and power loss due to friction.



Not sure Zero can pull this off for 2013. Upgrades may instead provide an incremental range improvement and offer nice to haves like WiFi communications to support a range of applications, such as:
1. Programmable controller that you can tweak via an iPhone app
2. Maintenance schedule and service status with dealers and Zero
 

[wainair]

I hear you on the 2 speed gear box. That should also improve your range at speed a bit too as an added bonus to a better torque curve.

[protomech]

I don't think we'll see a capacity improvement, though improved aerodynamics could greatly extend range. I suspect they'll stay with the same system voltage for another year or two, at least for carryover models. The EIG cells are simply too large (ZF3 = 2p, ZF9 = 6p) to allow for small granular capacity increases, as they did with the Molicel cells in 2011.

Take a look at the two torque vs speed plots attached.

The BRD motor plot is really close to an idealized plot, eg constant torque until constant power.

Changing the gear ratio affects both initial torque before the taller gear enters constant power as well as the top speed in each gear.

The Zero is more complex - it is constant torque to a power peak and then power decreases gradually as RPM increases.

Changing the gear ratio affects not only initial torque prior to the power peak, but also where the power peak is located and the top speed.

In the Zero S example, the power peaks are located around 45 mph (short gearing), 55 mph (stock gearing), and 75 mph (tall gearing). Changing the gear ratio allows you to effectively place your power peak where you're riding .. sort of like you do on an ICE bike, only the power peak is typically about half of max motor RPM (3500 RPM for Zero, vs ~6500 RPM max) instead of near max RPM as on ICE.

I don't understand motors very well, but here's an intuition. I believe the BRD acts more like an idealized motor because of its higher voltage - like the race bikes. For any given power level, a higher voltage motor draws less current. Power lost to motor inefficiencies (as heat) can be roughly expressed as I^2 * R .. and R increases as the motor heats up. The BRD gets very little benefit from a transmission as long as it is above 30 mph or so; the stock gearing provides at least 65 mph speeds.

[protomech]

Notice too that the BRD bike has more than 2x the wheel torque of the Zero S, at least until 35-40 mph. At 65 mph it's still +50% wheel torque.

[stenling]

The Zeros now has excellent powertrains. I think it would be a good idea to focus on stability for the powertrain and avoid major changes. This is also important to minimise the risk for costly recalls.

My bet is that Zero will focus on styling improvements: LED lamps, lights exterior design, body panels, instrumentation, rims.

By the way: When will the 2013 models be presented?

Carl Anton

[protomech]

The 2012 bikes were announced at EICMA in early November last year. EICMA this year is November 15-18 .. don't know if they'll repeat, but it seems reasonable to me.

[stenling]

From personal experience with my first EV (Kewet CitiJet 5 1998 model) i know that good gear box design is not simple. Poor design gives problems with noise. A full gear box design where noise and stability is taken care of is a substantial investment. I doubt Zero will give priority to this.

With the exception of Tesla, almost all EVs on the market have opted for fixed gearing with good results.

Carl Anton

[Marshm]

For dirt riding, I like 6 gears.  It it nice to have the right gear for the situation.  Actually I like the close ratio gearbox of the 250F mx bike when geared down so first can be used for tough trails.  The problem is that top speed goes way down.  The E bike sort of has by default a no stall clutch even if it has gears, thats nice.  I use 5 or 6 gears for offroad riding, well mostly the first 3 gears in trails.  It is hard to believe just 1 gear will work well.  That BRD graph has so much more torque than the Zero, but with lower gearing the Zero's torque can go up to try and find the BRD level.  For offroad, I will never need or want more torque than the Zero?  Then why does the BRD have more?  Gears give some flexability to the vehicle to handle all the different conditions/situtations in offroad.  City riding is pretty basic, so maybe 1 gear might be ok there. 

I still have not ridden one of these bikes, and I think to really understand I would need to take it in some of the trails where I use the ICE bike.  Being so conditioned to ICE engines and needing gears, it is hard to visualize something different.  I am open to no gears, but I still think gears may have some good merrit on E bikes.  Especially for dual sport bikes where they need both low speed offroad and high speed freeway capability.  I think ICE bikes do not really do a good job with lowspeed offroad and highspeed freeway in the same bike.

[ZeroSinMA]

Notice too that the BRD bike has more than 2x the wheel torque of the Zero S, at least until 35-40 mph. At 65 mph it's still +50% wheel torque.

Fair point re BRD vs Zero torque curve. I guess my point is that generally all electrics have a similar curve that can maybe be improved with a 2-gear transmission, in theory.



Any way you look at it, Zero is doing a great job delivering more power at all speeds. As others have said here, as is apparently Zero's assessment, don't mess with success.

[trikester]

Marshm, I'd be willing to bet that if you ride an electric bike on dirt trails you will never want to ride an ICE bike there again. That's what happened to me. I had no idea how much advantage an electric had in dirt riding until my first dirt ride on mine. The beauty is that there is always torque at any speed. I used to always be shifting because in the tight, slow parts of the trails I'd be in a low gear, then I'd come to a faster section and I wouldn't have the speed available in the low gear so I'd have to shift up to get speed, then back down again in another slow section. On my ZERO DS I can go slow with lots of torque and then just accelerate to a higher speed in an open part of the trail. Come to a difficult section just brake and get on the throttle. Come to a surprise very steep pitch just hit roll the throttle - no down shift. No stalling out on a surprise steep climb. Somebody asked me how steep it will climb and I answered that any hill it wouldn't climb I wouldn't want to be on.

Bottom line is: I think that any dirt riders that try one of these bikes will be sold on them for dirt trails. Unless of course if they love noise, shifting all the time, and a hot pipe when they fall. When my DS fell on my leg it was almost a pleasure to just relax and take my time getting up - nothing hot there.

Trikester

BTW - I'd like to electrify one of my dual-sport trikes ("Trikester" comes from the D-S trikes I've built).

[Biff]

For dirt riding, I like 6 gears.  It it nice to have the right gear for the situation.  Actually I like the close ratio gearbox of the 250F mx bike when geared down so first can be used for tough trails.  The problem is that top speed goes way down.  The E bike sort of has by default a no stall clutch even if it has gears, thats nice.  I use 5 or 6 gears for offroad riding, well mostly the first 3 gears in trails.  It is hard to believe just 1 gear will work well.  That BRD graph has so much more torque than the Zero, but with lower gearing the Zero's torque can go up to try and find the BRD level.  For offroad, I will never need or want more torque than the Zero?  Then why does the BRD have more?  Gears give some flexability to the vehicle to handle all the different conditions/situtations in offroad.  City riding is pretty basic, so maybe 1 gear might be ok there. 

I still have not ridden one of these bikes, and I think to really understand I would need to take it in some of the trails where I use the ICE bike.  Being so conditioned to ICE engines and needing gears, it is hard to visualize something different.  I am open to no gears, but I still think gears may have some good merrit on E bikes.  Especially for dual sport bikes where they need both low speed offroad and high speed freeway capability.  I think ICE bikes do not really do a good job with lowspeed offroad and highspeed freeway in the same bike.

If you want to see how an electric dirtbike compares to Gas bikes, check out these videos.





The second video is from a 6hour race, where the Zero MX competed in Open Expert class, and came 6th in the class and 16th overall (of a field of almost 80 teams)

-ryan

[ZeroSinMA]

For dirt riding, I like 6 gears.  It it nice to have the right gear for the situation.  Actually I like the close ratio gearbox of the 250F mx bike when geared down so first can be used for tough trails.  The problem is that top speed goes way down.  The E bike sort of has by default a no stall clutch even if it has gears, thats nice.  I use 5 or 6 gears for offroad riding, well mostly the first 3 gears in trails.  It is hard to believe just 1 gear will work well.  That BRD graph has so much more torque than the Zero, but with lower gearing the Zero's torque can go up to try and find the BRD level.  For offroad, I will never need or want more torque than the Zero?  Then why does the BRD have more?  Gears give some flexability to the vehicle to handle all the different conditions/situtations in offroad.  City riding is pretty basic, so maybe 1 gear might be ok there. 

I still have not ridden one of these bikes, and I think to really understand I would need to take it in some of the trails where I use the ICE bike.  Being so conditioned to ICE engines and needing gears, it is hard to visualize something different.  I am open to no gears, but I still think gears may have some good merrit on E bikes.  Especially for dual sport bikes where they need both low speed offroad and high speed freeway capability.  I think ICE bikes do not really do a good job with lowspeed offroad and highspeed freeway in the same bike.

If you want to see how an electric dirtbike compares to Gas bikes, check out these videos.





The second video is from a 6hour race, where the Zero MX competed in Open Expert class, and came 6th in the class and 16th overall (of a field of almost 80 teams)

-ryan

Watching the 1st video of a wet trail race, the MX advantage is that it's 50 lbs lighter for similar power. Doesn't bog down in the mud and can accelerate better in the mud.

The advantage is less in the second dry trail race where bogging down is not a factor.

[trikester]

I'll bet that the 2013 DS will have a 17" rear wheel. If I buy another one I won't have to go to the trouble of modifying the rear wheel to 17" like I did on the 2010 and 2012 DS's. It's a pain in the ass to make the change and I'll be very pleased if ZERO finally makes a change, on the DS, that they should have made in 2011 or 2012. Hopefully if (when) they make this change they will allow enough swing-arm cross brace clearance for big knobby tires (that's the whole point in going to the 17" rim - broad choice of DS tires).

I had to cut away part of the cross brace to make the modification on my bikes.

Trikester

[wainair]

17" rear really is a must. I was just doing some window shopping on the internet and there really are no options out there for 16" DS tires. I hope they monitor the forum and listen to some of these requests/wishes!

[trikester]

Even though the Kenda K270 17" tires are listed as rear tires I have a K270 4.6" x 17" on the front which works well and a K270 5.1" x 17 on the rear which works well.

A lot of dirt riders have said good things about the K270 series. I didn't know that when I picked those out based on looking at the tread and sizes. It's always good when other riders say I picked a good one 

Trikester