Another DH Project

[motomoto]

How heavy is the kit (without batteries)?

About 10 lbs.

[recumpence]

Post it Matt!!

I'll try my best when I get a chance.

Matt

[VSkudarnov]

How heavy is the kit (without batteries)?

About 10 lbs.

Not bad at all. And what is the reduction ratios (primary and secondary)?

[motomoto]

It's 18 to 72 with the belts, 9 to 50 with the 250H chain, and 14 to 42 to the crank,
for a grand total of 1 (at the crank) to 66.6 (at the motor). I wanted the 6,000 rpm
motor to turn the crank at 90 rpm

[Whiplash]

Cool! Very similar to mine at approx 120 rpm max at the crank, so how is it running?

[motomoto]

I haven't broken it yet. I demo it a couple times a day. It still
hauls ass. Sometimes I turn it wide open and click through the
gears. It kind of bangs pretty hard when it shifts. I think it is
going to be pretty fun out in the dirt. I should be able to get
some more stuff done later this week.
I did a Solidworks mockup of the skid plate.

skid plate.jpg

(90.73 KiB) Downloaded 3 times

[VSkudarnov]

It's 18 to 72 with the belts, 9 to 50 with the 250H chain, and 14 to 42 to the crank,
for a grand total of 1 (at the crank) to 66.6 (at the motor). I wanted the 6,000 rpm
motor to turn the crank at 90 rpm

Very cool. You could also use 13T freewheel from ACS, very good quality - crank rpm will go down to 83.

[Whiplash]

I bet its a blast in the dirt, and truthfully it should last longer in a place that allows some wheel spin! Keep an eye on the rear freewheel, I have heard these can be a weak link!

[motomoto]

Very cool. You could also use 13T freewheel from ACS, very good quality - crank rpm will go down to 83.

I have one, just haven't justified putting it on yet.

[briogio]

If you decide to make a kit, I'll be first in line

[Whiplash]

Any updates yet? Curious to hear how its going?

[motomoto]

I built a forming tool for the skid plate yesterday and formed a sample
piece of plastic and it came out good. Next, I have to machine a real
blank to form. I am pretty buried right now in work for customers, so
it might be a few days before I have something to show. The throttle
is coming along. It's going to be something unusual.

[Whiplash]

Cool! Can't wait to see it!

[St.Alpine]

Hi,

I just finished reading this incredible article. Iam a Mechanical Engineering Student myself and I always loved these wonderful mechanical structures. Its a pleasure to see the fotos and imagining the great work you've put into designing this drivetrain.

I just found out and got really into Ebikes not that long ago, but Iam already hooked and my former internal combustion fascinado has switched to the electric revolution.

When I was reading through your thread I couldn't honestly understand it anymore why people use hubmotors. You get so much more power out of rc motors, and that doesn't even involve the mass of unsprung weight you have with a hubmotor.

Can't wait to see the video !

[motomoto]

I finished the bike up last Saturday and have been riding it on a motocross track. It has a few issues
but I am working those out. It doesn't roost around the track like my YZ125, but it is pretty fast for
a bicycle. No video yet but I am working on it. I refuse to put out anything lame.

[AussieJester]

I finished the bike up last Saturday and have been riding it on a motocross track. It has a few issues
but I am working those out. It doesn't roost around the track like my YZ125, but it is pretty fast for
a bicycle. No video yet but I am working on it. I refuse to put out anything lame.

Best rc MTB non-frock conversion without modding the frame, on Endless Sphere....IMHO

Unbelievable workmanship truly impressive extremely happy for you to have it up and running
and very much look forward to the video. Your work is not only amazing but inspirational!

KiM
frock killer; frock annihilation; frock killer; frock annihilation; frock beater; frockinator;

[Whiplash]

I finished the bike up last Saturday and have been riding it on a motocross track. It has a few issues
but I am working those out. It doesn't roost around the track like my YZ125, but it is pretty fast for
a bicycle. No video yet but I am working on it. I refuse to put out anything lame.

IMG_1185.JPG

IMG_1186.JPG

IMG_1187.JPG

Is that 10AH in there? very nice design! I would LOVE to see it perform! TOP quality for sure!! It seems like it is ALMOST quick release off the bike!

[nicobie]

Simply stunning workmanship.

[rodgah]

droool

re power: get a 3220 in there.....or 2 hahaha. Actually with this design I think one of Matts proposed 4### motors will be sweet. More power than you can poke a stick at and if its low KV and run in WYE you might be able to get away with just one reduction stage. Probably want to carry more battery then....ahh everything is a trade off.

Cheers
Rodger

[recumpence]

You need at stuff a 4 turn 3220 in there. You will have 8 to 9kw of raw power. It will ride more like a 125 that way (well, maybe like a 85).

Matt

[Whiplash]

So do you think the gears will solve the Rc controller issues? It seems like you would Because of a far smaller load on take off..

[recumpence]

Actually, the slipper clutch solves that too. I am still running all of my bikes with a single ratio. But, they all have a clutch. That clutch is the Holy-Grail of RC systems, at least until we get a phase-current limited controller, that is.

Matt

[Whiplash]

Cool, I am thinking of switching to the R/C controller for my design for space/weight savings...

[motomoto]

KiM

Best rc MTB non-frock conversion without modding the frame, on Endless Sphere....IMHO

Personally, I would never ride one of those frockers.


Whiplash

Is that 10AH in there?

I think it would be a 5AH at 44 volts with 2 5AH 22v batteries in series.
That was the biggest compromise in the design since the beginning, not enough battery.

But the design had a couple of things going for it: 1. Everything was in one unit that just bolted on.
2. The weight was placed right where you want it.

I bought a couple of those long 1" x 2" x 12" 5AH batteries that I am going to mount along the top of the unit on each side
of the down tube. I got some carbon fiber to make a slot for the batteries so they will be covered from the side. I am trying
to keep it looking good. The last month has been spent trying not to screw it up with some wrong design aesthetics. I got lucky
with this project starting out good so I've tried to continue to make good design decisions to the end. It's not unusual for me to 'paint
myself into a corner' design wise, and have to give up and start something else.

This project was to get my feet wet with the whole electric thing. It accomplished that.

Rodger

re power: get a 3220 in there.....or 2 hahaha. Actually with this design I think one of Matts proposed 4### motors will be sweet. More power than you can poke a stick at and if its low KV and run in WYE you might be able to get away with just one reduction stage. Probably want to carry more battery then....ahh everything is a trade off.

Matt

You need at stuff a 4 turn 3220 in there. You will have 8 to 9kw of raw power. It will ride more like a 125 that way (well, maybe like a 85).

I made it so that a longer motor would fit right in. One of the problem I am dealing with now is that the thing wants to flip over backwards all the time. It may sound
fun but it's not. When you are on the blacktop you have to lean over the bars freakishly so when it hits that sweet spot in the powerband you don't end up on your kester.
In the dirt, it will suddenly wheelie coming out of a turn and scare the crap out of you. Scary, not fun. The bike has too much suspension and not enough wheelbase. The
other problem is that it keeps snapping chains. In the higher gears it actually jumps a tooth on the rear cluster with a nasty clunk which eventually breaks the chain.
We are putting on some fresh gears and a new short throw derailleur that is adjusted properly and see how that works. I am also going to make a new 250 sprocket that
will change the 50 tooth to a 40 tooth. That should send 20% less torque to the back of the bike and will make use of the lower gears on the cluster.

I think adjusting the slipper clutch properly will solve some problems also, I've had it cranked up tight all this time.

The bike weighed in at 56 lbs. About 13 lbs. for the unit.

[motomoto]

I mean the bike with the unit weighs 56 lbs.