Build No. 2 - Reduction Drive - now w/ NEW video

[mauimart]

Spent most of the day drilling holes. I must say that I am very pleased with the outcome. Looks a lot better and I saved a whopping 10 oz (255g) .

[motomoto]

Nice job on your build. I think that this is the best way to do the mid drive thing. A couple of reductions, and you
have all the gears in the back to match all the conditions. Uphill, downhill, it doesn't matter, you have the right
gear for the occasion.

[Whiplash]

Exactly! !

[mauimart]

Nice job on your build. I think that this is the best way to do the mid drive thing. A couple of reductions, and you
have all the gears in the back to match all the conditions. Uphill, downhill, it doesn't matter, you have the right
gear for the occasion.

Exactly! !

Indeed. This build is quite versatile:

Full suspension, albeit crappy stock shocks.

Full range of gears. I can effortlessly climb 15% grade without pedaling and reach 37 mph on the flats. I could probably do 40 mph if my shifter would get the chain on the smallest cog on the rear... I have still yet to sort out the shifting to get through all 8 gears.

I can pedal upwards of 20 mph with reasonable cadence because of the low kV wind on the motor.

One of the things I don't like is that with the 3 chains and 2 freewheels in the setup, there if quite a bit of slack or play between motor spinning and back wheel spinning. I measured it to be half a revolution of the motor to pick up all the slack in the chains and freewheels. This causes significant lag when applying power and makes for somewhat jerky performance when under small loads.

In the mean time I would like to upgrade the front fork to something better. Does anyone have any recommendations (brand and source) for a decent shock that works well for light to moderate off-road use, and will not break the bank????

[Uteanooga]

[mauimart]

Just swapped out the Kelly for a cheap Hual Tong controller for some testing. Details at this thread:

viewtopic.php?f=2&t=29469&start=585

[mauimart]

Some improvements to the build over the weekend:

After testing the modded Hua Tong 38A/72V controller I decided to abandon it as it provided violent surges at about 25% throttle threshold- very jumpy to say the least and if I was not expecting it would have thrown me off the back. I was able to get over 2000W continuous and 2900W peak from it once it settled in at WOT. Anyway I ditched the seat post controller mount and moved the Kelly controller into the battery box. I also added a 50A fuse.

Hua Tong Test video:

[mauimart]

Here's a brief update on the project:

I decided on the generic 20C lipos instead of the nano-techs. Based on the higher cost of the nano's and the fact that I would rarely exceed 8C the 20C cells made the most sense. So I have 6 pieces of the 6S/5Ah bricks configures as a 18S/10Ah pack. Full-up bike weight is 65lbs. I seem to have one cell in one of the bricks that is not 'playing nice' and it looks like I'll be returning that one to Hobby King.

I have been riding the bike almost daily and my normal commute consists of a 7 mile climb of approx 1700 feet elevation gain. I do a fair amount of pedal assist and end up spending just over 4Ah or 300Wh on average. The deepest discharge to date was 7.1Ah or 490Wh with an Amax of 77A (all according to the CA). I have not exceeded a motor temp of 100C at this point yet I think I could easily do this with no pedal assist and a heavy throttle. My guess it that I can sustain approx. 2000W input power without the motor reaching critical temperatures. I have also verified that the motor can take 5000W input power for short bursts. I am amazed at the power output of this tiny motor yet not surprised that it struggles to dissipate the heat. I have some future plans to do some testing on flatter terrain to see how it performs. The current gearing allows me to hit 38mph. My goal is to change the gearing, at least temporarily, to see if I can hit 50mph on the flats with this setup. I think it may be in the cards. I also have a stock wound motor with a significantly higher kv that would get me there assuming the Kelly could handle it. Has anyone hit 50mph with the C80-100 outrunner?

The best part of riding this bike is letting cars pass you and then accelerating and hanging on their tail. The double-takes in the rear view mirror are priceless...

Martin

[mauimart]

Thouht I'd try for a 50 mph run today so I removed the crank and replaced the 30T chainring with 44T. Theoretical max speed would be 53mph. I charged up the Lipo to 4.2V/cell to get every ounce of power and energy - I normally charge to 5.15V/cell. Hooked up the DIY arduino-based Cycle Analyst data logger and the arduino GPS logger. I then took the bike out to the nearest flat stretch of road I could find (12 feet of decline in 1/4 mile according to google earth) and with a slight cross wind I hit 50mph according to the CA. Unfortunately I forgot to insert the SD card into the GPS logger so no gps confirmation at this point. I was on my fourth attempt when the fuse blew (50A AGU). I will upgrade to a 80A fuse, dial up the controller to 11, and try another time. I may even have to strap on the stock wound, 130kV C80100 as I have run out of gears. That motor will most likely fry my controller so maybe not. This bike really has no business going over 40 mph anyway. Oh well... For now, here is some data.

[mauimart]

Update:

I went for a 36 mile ride the other day and on the way back my C80100 "threw" a bearing. Needless to say I was in limp-home mode for the last 5 miles.
Here's the carnage:

Busted Bearing

P1060828.JPG (181.67 KiB) Viewed 469 times

After I replaced the bearing I thought I would do a little more work on the bike. I added a chain tensioner to the first stage reduction - long overdue. I used the nylon wheel from a screen door roller as the tensioner and it works ok. Eventually I would like to use some sort of roller with a bearing in it to reduce friction and noise. Here's a brief video of the tensioner in action.



I then noticed an old bike that's been sitting dormant since when my son was young and I decided to replace my 26" back wheel with the 24" from the kids bike. Here is the result:

24" Rear Wheel

P1060922.JPG (160.29 KiB) Viewed 469 times

Other side

P1060924.JPG (172.24 KiB) Viewed 469 times

I think it looks bad-ass. A quick power test was now in order, just to make sure everything was "operational". Here's what a front tire slick with 60 psi will get you when riding in loose gravel.

Road rash

P1060926.JPG (154.88 KiB) Viewed 469 times

Video of crash to follow...

[mauimart]

Here is the crash video. The only damage to the bike was a busted pedal.

[bzhwindtalker]

That thing seems to push! Apart form you wearing a hawaian shirt and no helmet, the crash was kinda lame haha, I crash like that 2-3 times per ride

[mauimart]

Some updates to the bike:

New set of Vuelta wheels with hubs for disk brakes.
Avid Elixir 3 hydraulic disc brakes.
SRAM X7 Shifter
SRAM X9 Derailleur
SRAM 9-speed cassette (11-34)
SRAM chain
Hinged battery box cover with magnet latching.

All that's missing now is a fork upgrade....

[mauimart]

Here's a new video shot entirely on my new RD32II ($119 US) in 1080P/30fsp. I'm quite satisfied with its performance thus far.



EDIT: Version that will play on mobile devices: http://www.youtube.com/watch?v=agWOH5dl9VQ

Here's how I mounted it to the bike. The v-brake bosses made for convenient attach points.

[mauimart]

With my recent upgrade of shifting components, I can now shift under WOT. Sounds a bit like an F1 car, at a lower frequency of course...

[h0tr0d]

How wide is your alu box?
And how that in terms of pedalling comfort?

Great build and vids!!

Congrats!

[mauimart]

.
The width of the battery box is right around 17cm (6.7 in). I made it that width to comfortably hold 3-wide of the Turnigy 6S 5000mAh packs. I do quite a bit of pedaling on this bike and have had no issues with the battery box getting in the way (no chafing). I did add a longer spindle (158mm IIRC) in the bottom bracket to allow for clearance between the crank and the reduction gears on the jack shaft.

I am currently in the process of upgrading to a 'real' suspension fork. Pictures when done...

[crossbreak]

nice bike and vids! the setup reminds me of my first build, which is disassembled cause it drew my bat empty in minutes . thanks for posting this stuff!

i hope your sprocket cassette holds up longer than mine. I used a shimano 9-speed cassette 32T-11T with shimano chain on my 1000W middrive test setup. It holded up for about 300km till the 11T sprocket started to slip. The 12T slipped followed 600km later, then I bought a 9-speed SRAM gear hub. It holds up well (about 1500km-2000km yet, my odo sadly was reset).

I hope you have an odometer on your bike. Could you be so keen to keep an eye on how many miles your cassette/chain survives under these circumstances? I plan for another bike with derailleur, that's why I ask. I plan to only use 13T and larger because of my bad experiences. Maybe your SRAM cassette is better quality?

I bought a RST Peak 130mm fork at the bay for 40 bucks a year ago, the oil damper of the forks works really sensitive and adjustable at a wide ratio. I'm very content about it, didn't expect that. It's a bit more heavy then the expensive forks but almost impossible to break. I can only recommend.

[pff7]

Love it, love it!!!! so nice----by the looks of it seems like it would pedal just like a regular bike w/o power? Excluding weight of motor, drivetrain,battery,ect. seems your freewheel would make the bike pedal just normally, am I right?

[mauimart]

i hope your sprocket cassette holds up longer than mine. I used a shimano 9-speed cassette 32T-11T with shimano chain on my 1000W middrive test setup. It holded up for about 300km till the 11T sprocket started to slip. The 12T slipped followed 600km later, then I bought a 9-speed SRAM gear hub. It holds up well (about 1500km-2000km yet, my odo sadly was reset).

I hope you have an odometer on your bike. Could you be so keen to keep an eye on how many miles your cassette/chain survives under these circumstances? I plan for another bike with derailleur, that's why I ask. I plan to only use 13T and larger because of my bad experiences. Maybe your SRAM cassette is better quality?

I actually worry more about the chain (crank to cassette) failing as it's not designed for these loads. Hopefully the SRAM cassette proves better than what you experienced with the shimano. Most of the time I try to keep the acceleration levels low so as not to over stress the already over stressed components. I always pedal first when starting. I also rarely use the 11T - only when doing speed runs and I need to exceed 45mph. Although none of these precautions has prevented me from getting 100A peaks on the CA.

I do keep records (dist, Ah, Whr, etc.) of each trip and I might post some data once I have a few more cycles on the bike. For the most part I am only keeping track of mileage when the bike is powered by the motor. My morning commute is all downhill so I don't even turn anything on, including the CA.

[mauimart]

Love it, love it!!!! so nice----by the looks of it seems like it would pedal just like a regular bike w/o power? Excluding weight of motor, drivetrain,battery,ect. seems your freewheel would make the bike pedal just normally, am I right?

Yes, the bike functions very close to a non-ebike with the biggest difference being the weight. It's 63 lbs now (down from 65 with the new fork ) which is 26 lbs more than what it weighed prior to conversion. There are two freewheels, one on the jackshaft and the other on the cassette so yes it does pedal normally and you don't have to pedal along with the motor if you choose not to. And I do pedal quite a bit. For example a recent ride went like this:

35.7 mi
6.17 Ah
430 Wh
12 Wh/mi
16.9 avg. sp.
2hr6min

[h0tr0d]

.
Are your wh/mi correct? if so, amazing figure!!!

Is your turnigy "stock" or heavily modded?

Love it, love it!!!! so nice----by the looks of it seems like it would pedal just like a regular bike w/o power? Excluding weight of motor, drivetrain,battery,ect. seems your freewheel would make the bike pedal just normally, am I right?

Yes, the bike functions very close to a non-ebike with the biggest difference being the weight. It's 63 lbs now (down from 65 with the new fork ) which is 26 lbs more than what it weighed prior to conversion. There are two freewheels, one on the jackshaft and the other on the cassette so yes it does pedal normally and you don't have to pedal along with the motor if you choose not to. And I do pedal quite a bit. For example a recent ride went like this:

35.7 mi
6.17 Ah
430 Wh
12 Wh/mi
16.9 avg. sp.
2hr6min

[pff7]

But when you pedal w/o using motor, in other words with no throttle, when pedaling are you turning the motor or is the motor turning via drive chain when you pedal? When your applying throttle I assume freewheel let's you keep feet on pedals without turning, but does it work vice versa? And if motor turns via only pedal power I'm assuming from what you stated that the motor turns very easily then.

Love it, love it!!!! so nice----by the looks of it seems like it would pedal just like a regular bike w/o power? Excluding weight of motor, drivetrain,battery,ect. seems your freewheel would make the bike pedal just normally, am I right?

Yes, the bike functions very close to a non-ebike with the biggest difference being the weight. It's 63 lbs now (down from 65 with the new fork ) which is 26 lbs more than what it weighed prior to conversion. There are two freewheels, one on the jackshaft and the other on the cassette so yes it does pedal normally and you don't have to pedal along with the motor if you choose not to. And I do pedal quite a bit. For example a recent ride went like this:

35.7 mi
6.17 Ah
430 Wh
12 Wh/mi
16.9 avg. sp.
2hr6min

[mauimart]

.
Are your wh/mi correct? if so, amazing figure!!!

Is your turnigy "stock" or heavily modded?

The Wh/mi figure is accurate as I pedaled a significant amount. The motor was rewound with 9T #14 AWG in wye configuration and bearings were replaced at least twice now.

But when you pedal w/o using motor, in other words with no throttle, when pedaling are you turning the motor or is the motor turning via drive chain when you pedal? When your applying throttle I assume freewheel let's you keep feet on pedals without turning, but does it work vice versa? And if motor turns via only pedal power I'm assuming from what you stated that the motor turns very easily then.

The pedals will not drive the motor as there is a freewheel on the side of the jack shaft that drives the crank. And yes the motor does not cause the pedals to turn as there is a freewheel in the spindle assembly. The drawback of 3 freewheels in the drive system is that there is quite a bit of play or slack between the motor and wheel. Not a huge issue but definitely noticeable.

Here is a video of the aforementioned ride. It's over 2 hours compressed into 8 minutes.

[Byte]

The gear shifting is awesome!