Electric Electra 36V 970W 7-speed shifter

[KCvale]

What can I say...
This build blows me away.

Before I start with the build parts... for operation you only need the even numbered gears and for the most part just 4th and 6th which is how I shift that 7-sprocket derailleur final dive that I wish was it just a 3-speed internal but that is beside the point...

I had to do a LOT of custom stuff to house that battery I had built for my Trike builds but I tell ya, this thing will outperform 95% of my previous builds in every way above and beyond sheer top speed because it it such a joy to ride.

Quick off the line, quiet, and faster than you need and as a super double bonus not scarey to ride at all and I think that says it all ;-}

 

[KCvale]

This bikes customer took a little (just some road rash) spill on gravel that jarred the motor enough to mess up chain alignment so while I had it in the shop for a free fix and mount upgrade I took some more pics in 1280x1024 for more detail so just click the pics for the full size.

Tech details to note about this 'Re-Tasking of Existing Expensive Parts' by the seat of my pants custom build can be learned by reading my 6 page topic about my foray into building adult electric trikes that would exceed anything out there for the price here.
http://motorbicycling.com/showthread.php?t=44144

In short I had overkill parts meant for a big adult trike and a new customer that wanted the most kick butt legal bicycle he could lay down in an SUV and not have to mess with gas or maintenance.

I started with what to do with that huge battery and tuck in the electronics, wires and motor and constructed a battery frame with killer 3 point mounts, a spring tensioner, and tucked the controller under the battery and added some weather fairings to cover them and give it a cleaner look.

It won't win any sexy e-bike beauty contests I didn't pick the bike but it is an outstanding machine to ride around if you stick to the even gears making it a 3-speed as first gear makes it a wheelie machine, the power is greater than the gear ratio per gear, and though you can hit 7th it is pretty big bend in the 7-speed chain towards the outer JS sprocket and considering the speeds you get in 6th not a very good idea ;-}

 

[Sidewinder Jerry]

What can I say...
This build blows me away.

Before I start with the build parts... for operation you only need the even numbered gears and for the most part just 4th and 6th which is how I shift that 7-sprocket derailleur final dive that I wish was it just a 3-speed internal but that is beside the point...

I had to do a LOT of custom stuff to house that battery I had built for my Trike builds but I tell ya, this thing will outperform 95% of my previous builds in every way above and beyond sheer top speed because it it such a joy to ride.

Quick off the line, quiet, and faster than you need and as a super double bonus not scarey to ride at all and I think that says it all ;-}

KC since you're only using 2,4,6 is it safe to assume the sprockets are 24, 20, 16? You could get a SunRace 5 speed mountain bike freewheel. They got them on eBay now. The sprockets are 28, 24, 20, 16, 14. It uses a lock ring to secure the cogs. You can cut the outer part of the 28 off. You just need the inner part of the 28 for a spacer on the core. The 14 would need the teeth ground down. Then you'd have your 3 speed freewheel. You can put a stop inside of any twist shifter. Then sand off the extra numbers.

On my bike I made a 5 speed out of a 7 speed. 34, 28, 24, 20, 16. This is what worked best with my autoshifter. It was you who early on told me less gears with the ratios spread further apart is better. Human legs are only about 1/2 HP at best. That's why cyclist need gear ratios closer together. Engines and motors are much stronger and work best with the ratios spread further apart. I discovered this to be very true with my build. When I ran 7 and 8 speeds I had to accelerate slowly or the chain would jump across the cogs. After spreading the ratios further apart the chain is on a sprocket a little longer before transitioning to the next sprocket. This actually speeded up the acceleration. I did a tread on building custom freewheels. LandRider Jerry 5 Speed Freewheel. You can also go to my profile and I have an album on how to do it.

 

[KCvale]

KC since you're only using 2,4,6 is it safe to assume the sprockets are 24, 20, 16?

7 speed range on the Shimano is 14-28 so that would be about right.

It was you who early on told me less gears with the ratios spread further apart is better. Human legs are only about 1/2 HP at best. That's why cyclist need gear ratios closer together. Engines and motors are much stronger and work best with the ratios spread further apart. I discovered this to be very true with my build.

Exactly, different engines have different sweet-spot RPM ranges but they all are much farther apart than human power gearing.

I learned that lesson the hard way back in late 2010 to early 2011 when I played with my Bad Mojo Giant Suede Nuvinci Dev Kit high performance build for Death Race 2011 in Tucson, AZ was being built.

My very first venture into the NuVinci world of unlimited gear ratios seemed like a great idea when I could program the automatic shift controller to shift ratios on it's own via programmable shift tables which I admit as a 25 year computer geek I really liked, but I didn't even consider engine power ranges which with that build were extreme for me at the time.

Just kidding about that PhotoChoped pic above, one of my internet friends made that for fun, but this real thing could have made a decent showing with a good rider as my days of racing are long gone as I feel the pain of most everything I ever seriously injured back then every day these days.

I have to admit the wired 'remote control/read out' was pretty cool.

But again, I didn't need more gears, what was needed was fewer acceptable wide ranges to accommodate the riders likely terrain and overall weight differences for best performance, and just a simple way to switch between modes.

Anyway the DEV kit auto came off when it failed and a manual Nuvinci hub wheel was put it in and again the same thing but manual that made my left hand tired drove home the point of less ratios is better if they set for the engines desired ratios.

As far as this electric is concerned with a 7 it may be 1-3-7 when traveling up a long gentle slope with stops so the ability to have those ratios is handy, and messing with a derailleur's rear sprockets for fewer seems good if you can use a fatter drive chain but again it all comes down to how you shift with what you have based on the engines sweet RPM spot range.

To me the ideal automatic shift controller would do shift changes based on engine rpm and throttle position just like you enjoy in your auto tranny car and NuVinci was close but just didn't follow through because their CVT fluid simply would not hold up to much more than human power and way more options that needed for a motorized bicycle.

 

[Sidewinder Jerry]

Here is the tread on building a custom freewheel.

http://motorbicycling.com/showthread.php?t=46033

The 5 speed SunRace could be converted into a 3 speed. The way I made a 7 speed into a 5 speed. You'd have to cut the outer part of the 28 off where the teeth are and keep the spline part to be used as a spacer. The 14's teeth would have to be ground down. My personal chain of choice is a Sram 890.