Light weight full suspension mountainbike --WITH VIDEO--

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Re: Light weight full suspension mountainbike build (finally

Post by recumpence » Aug 07, 2016 8:52 pm

I manufacture a sprocket adapter that sandwiches between the disc and hub. It offsets the sprocket 3/4 inch inward to provide room for the caliper. The chain always moves with the wheel. The drive unit freewheel is on the drive unit output shaft.

Last I checked, no load power consumption was on the order of 300 watts at full throttle on my other bike (identical drive system). I have not checked it on this bike yet.

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Re: Light weight full suspension mountainbike build (finally

Post by bionicon » Aug 10, 2016 3:18 am

Hi Matt i like your light weight bike, it still look very like a normal bicycle(sometimes very important :D ) I wonder did You ever thought about putting a freewheel on Your rear sprocket? I have also a leftside drive and find it sometimes anoying when i am at a certain speed and let loose the trottle , i still hear the chain rolling, instead complete silence.

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Re: Light weight full suspension mountainbike build (finally

Post by recumpence » Aug 10, 2016 6:54 am

bionicon wrote:Hi Matt i like your light weight bike, it still look very like a normal bicycle(sometimes very important :D ) I wonder did You ever thought about putting a freewheel on Your rear sprocket? I have also a leftside drive and find it sometimes anoying when i am at a certain speed and let loose the trottle , i still hear the chain rolling, instead complete silence.
Two issues with adding a left side freewheel;

#1 It is extremely difficult due to the overall design of the rear wheel.

#2 The extremely high power of many of my systems would be hard on all but the most durable freewheel if mounted at the rear wheel. Mounting the freewheel on the output shaft of the drive unit increases the freewheel RPM while decreasing the torque loading on that freewheel due to the higher RPM of that part of the system.

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Re: Light weight full suspension mountainbike build (finally

Post by recumpence » Aug 14, 2016 8:53 am

So far, I have about 100 miles on the bike without any problems. It is great being able to hop down curbs, run through trails and overall have bashing around fun on an ebike.

I am 100% happy with the bike.

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Re: Light weight full suspension mountainbike build (finally

Post by spinningmagnets » Aug 20, 2016 12:02 pm

Finally had some time to write this up. Congratulations to Matt on a great build, and thanks for sharing the process and pics.

https://www.electricbike.com/matts-full ... mid-motor/

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Re: Light weight full suspension mountainbike build (finally

Post by recumpence » Aug 20, 2016 4:58 pm

Thanks alot. The article looks great. :mrgreen:
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Re: Light weight full suspension mountainbike build (finally

Post by recumpence » Aug 26, 2016 10:11 pm

I have around 200 miles on the bike without a single problem. At this point the next step is to fabricate a GoPro mount to hold the camera out to the side and behind (aiming forward) to get a view of the drive system and suspension working as I ride the bike. I think that would be a cool video.

I may set that up tomorrow in the shop so I can get some good video footage.

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Re: Light weight full suspension mountainbike build (finally

Post by recumpence » Aug 28, 2016 4:47 pm

A quick video of the bike as a test for the seat post GoPro mount I built today.

https://youtu.be/39eIZnbzb28

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by LI-ghtcycle » Aug 29, 2016 12:54 pm

Wonderful Video! :D

It looks like when you first started taking off in the grass it wants to pull the front up pretty hard, maybe lifting about an inch in 3rd gear? :shock:

Amazing build quality as always, top notch! 8)
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Aug 29, 2016 4:12 pm

LI-ghtcycle wrote:Wonderful Video! :D

It looks like when you first started taking off in the grass it wants to pull the front up pretty hard, maybe lifting about an inch in 3rd gear? :shock:

Amazing build quality as always, top notch! 8)
Yes the bike is geared for 35 miles per hour. With the power turned all the way up, I have to be very very careful with the throttle. On the pavement the front end keeps coming up as well. I can be going 26 or 27 miles per hour and crack the throttle and the front end will come up on its own. It has a lot of snap!

In the video I sort of hop down into the ditch and rolled the throttle on in the front wheel came up I got off the throttle then rolled back on in the front and came up again and I had to get off the throttle again. As I was turning around to go back the other way I reach down between my knees to the potentiometer to turn the throttle down for the return trip. Then as I turned left on the pavement you can see me get on the throttle then get off and I reach down turn the throttle back up then I get back on it and go full speed 35 miles an hour up the road.
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by cell_man » Aug 30, 2016 6:14 pm

That is an amazing build, hat's off to you Matt, it looks so well finished, really nice. I'd love to get a drive system off you sometime and have a project bike built around it. Just have to find the time, maybe next year :)
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Aug 30, 2016 8:01 pm

Thanks. I appreciate the kind words. The bike is running great. I am looking forward to many, MANY more mile on this bike. :D

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by 1000w » Aug 30, 2016 8:49 pm

Hey Matt,
Super impressive engineering. You have skillfully blended performance and stealth.
Thanks for sharing your great ideas.

Matt.P.

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Sep 01, 2016 4:15 pm

Thanks Matt!

Hey, how its Kim? I haven't heard from him in a couple of years.
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by cheekybloke » Sep 07, 2016 11:31 am

Superb quality build as always, are you still going to put the power through the bb on this one?
Darren

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Sep 07, 2016 12:49 pm

cheekybloke wrote:Superb quality build as always, are you still going to put the power through the bb on this one?
Darren
Good question. It is set up with Freewheeling cranks and would not be hard to change over to bottom bracket Drive. It is running so perfectly right now, that I almost hesitate to go to bottom bracket Drive. What I would love to do, however, is set up a bottom bracket drive with a 3210 motor. That would probably be excellent. :mrgreen:
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Nov 09, 2016 1:47 pm

Today's project is an interesting one. I have been curious about this for quite a while.

What if I decrease the motor size but increase the RPM? This bike is a perfect candidate for this because the 3220 motor it was originally built with is way overkill. So, going down in motor size will not be a problem because I already have far too much power on tap. So, to that end, I decided to replace the 3 turn Wye 3220 (10,000 RPM) to a 5 turn Wye 3210 (13,000 RPM). With this change, I also changed the final drive ratio the same amount to achieve the same top speed. This was accomplished by going from a 16 tooth freewheel to a 13 tooth. Here are my findings;

First, the bike lost nearly 2 pounds! So, it went from 54.5 pounds to 52.6 pounds. That is alot of weight to lose on such a light bike. Second, the torque dropped quite a bit. This is a wecome change. The bike used to snap wheelie frighteningly with every touch of the throttle. Now it will wheelie only when large throttle inputs are given. Lastly, the sound is higher pitched, but overall quieter. This is another welcome change.

The bike rides very well! It is still is geared for 34mph top speed. This is a touch more than I need. So, I may alter the gearing (different pulleys) to acieve a 30mph top speed. This will give me a touch more punch and less top speed along with easing the load on the [now tiny] motor.

Anyway, this is a completely successful project at this point. I am enjoying the light weight so much that I am ordering a bunch of parts to further drop the weight. I hope to have the bike below 50 pounds soon.

Enjoy the pictures. :D

Matt
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by macribs » Nov 09, 2016 3:26 pm

That is getting so light any day now you will have to turn to magnesium alloy to shave off more.
Look forward to see videos of the new 13.000 RPM setup. And see how the 3210 @13K deals with steep inclines and technical trials.
Bike is getting so light you hardly need the motor :wink:

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Nov 09, 2016 4:11 pm

One additional benefit turns out to be efficiency. I was wondering about this. I was worried that the efficiency would drop with the higher operating RPM. However, the reverse has proven to be true. The bike went from 23wh per mile at 20mph to 20wh per mile at 20mph! That is a 15% improvement in range. So, it looks like my previous 23 mile range is now 26 miles. I am not complaining! :mrgreen:

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by Ham » Nov 09, 2016 4:34 pm

macribs wrote:That is getting so light any day now you will have to turn to magnesium alloy to shave off more.
Look forward to see videos of the new 13.000 RPM setup. And see how the 3210 @13K deals with steep inclines and technical trials.
Bike is getting so light you hardly need the motor :wink:

Me too...I'd love to see some hills...direct drive astro fascinates me
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Nov 19, 2016 6:00 pm

I did some more testing today.

I replaced the main pulley. This changed the primary reduction from 6 to 1 up to 7 to 1. This dropped the top speed from 34mph to 28mph. I thought I would get more punch out of it. But, admittedly, the power to the wheel only increased slightly. However, with the lower top speed, the controller and motor run cooler and more efficient. So, it is a win. Plus I used a narrower belt and pulleys. This increased efficiency a bit as well. With the original 3220 motor, the bike has way too much power. With this 3210 motor, the power is adequate, but not as thrilling as I would like it to be. Below 12mph, if I snap the throttle, the front wheel comes up. But, anything over 12mph the acceleration tapers a bit. It is still powerful enough to be alot of fun, but it is not challenging. I think a 3215 would be perfect for this bike. But, we shall see. I will continue testing and tweaking to see what I can wring out of this tiny motor. :mrgreen:

Oh, I have carbon bars and new cranks to install. Those parts should shave about a pound off the bike. I also plan on lightening up the drive unit a bit. I would really love to get this bike in under 50 pounds.

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by Ham » Nov 20, 2016 4:47 am

I do love this frame!
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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Nov 24, 2016 2:52 pm

I received my carbon bars and new cranks. These parts should shave about a pound from the bike.

I have been experimenting with different composition belts and other small bits on this bike. All of the testing is paying off. I am almost 100% satisfied with it at this point.

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Re: Light weight full suspension mountainbike --WITH VIDEO--

Post by recumpence » Nov 26, 2016 9:53 am

I installed the bars. They shaved 7 ounces off the bike. The cranks will shave over a pound more. I hope to have them installed in a week or so.

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Re: Light weight full suspension mountainbike build (finally

Post by Mongo1 » Dec 05, 2016 10:57 am

Matt,
Stunning build (s)!! I assume you're using a variable resister throttle to the PWM board?? If so what make is it? I'm looking for one. Thanks!


recumpence wrote:The drive side chain is a simple BMX bicycle chain. For extremely high power systems (20kw or more) a trials bike chain is best. But, for this application, a normal BMX (single speed) bicycle chain works great.

280 amps is the peak battery amps the controller is programmed for. With the weight and layout of this bike, I would need to lean over the bars to see more than 200 amps and, even then, it would be a mere fraction of a second until the front end leaps up and the throttle is lowered to keep from flipping over.

The drive system is 6 to 1 ratio from the motor to the jackshaft. The output freewheel on the drive unit is 16 tooth (White Industries) and the rear sprocket is 60 tooth. This should give me a 30mph top speed.

Limiting torque is handled two ways on this bike;

First, the controller is programmed with low throttle response. This effectively gives a throttle ramp up delay, thus softening the throttle "Hit".
Second, there is an adjustable mechanical torque limiter (slipper clutch) inside the large belt pulley on the drive unit. This will be adjusted to slip a small amount under only the harshest conditions. This will protect the driveline.


Setting up a bike with these high output and light weight RC systems is like setting up a Formula-1 car or a factory two stroke dirt bike, if setup right it will run reliably with plenty of power. However, if setup incorrectly, problems will occur.

My black street bike is setup with this same drive unit, same motor, same controller. It runs wonderfully with hundreds of miles problem free. That bike is geard for 37mph and weighs 90 pounds (LOTS of lipo). This bike should be even more reliable because of the lighter weight and lower gearing. That is the hope, anyway. :mrgreen:

Oh, my black street bike is running a CA (setup for RC use). This bike will not have the CA for a few reasons;

#1 Complexity. I want this bike as simple as possible.
#2 Throttle response. The CA tends to dampen the throttle response and that affects the "Feel" of the bike. My Motoped had a direct PWM throttle like this new bike will be wetup with (no CA) and I prefered that setup for dirt use. For street use, I prefer the CA.
#3 Ease of build.
#4 Removeability. I want to be able to completely remove all electric components on this bike as quickly as possible so I can transport it on a bike rack on the rear of my car without worrying about rain. I plan on making the entire electric system removeable in less than 10 minutes for easy transport. The CA would increase removal time.
#5 Stealth. I want fewer components on the bars so it looks more like a normal bike (not like the drive unit is not visible :mrgreen: ).
#6 Distractions. On a long range street bike, I like being able to monitor amps, volts, battery state of charge, etc. But, on a dirt bike or trail bike, I prefer no distractions to take my eyes off the trail.

I may go with a CA eventually if I find I need it for some reason. But, I would rather go with a smaller motor to reduce power and wheelie tendency (and save weight) than resort to a CA to limit power on this particular build.

Matt

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