Holmes' #4, the mini bike (build 3ish)

Very nice, banana seats. Haven't seen those in a while. Sure looks more comfortable than regular seats.
 
Well, if one sits back far enough so the sit bones are supported then the front will be much too wide and cause pretty bad chaffing.
 
Chaffing? You think I pedal this beast with a high seat? :lol:


Gonna swap frames this week. I am tired of being so fearful of wheelies. I need more wheelbase! It should be a fast swap.
 
fast swap? Err, took a few hours longer than expected. Gonna go take a pic of the new setup, it actually rides very well.
 
Here she is, with an old Schwinn XS 1 bmx frame and some nast Roxx Shoxx Judy XC forks from back in the day. I use her to get around campus, easy to throw on a bike rack and in the back of my car.


Running a new controller now, so the throttle is much better on 24s a123. I still get about 8 miles of range even though I really beat on it during acceleration. Top speed 20mph, and it rips on the dirt! Great farm fun.
 
That's a nice lawn ripper John, I can't believe I haven't seen it till now! You should make a video, definately with wheelies! How sturdy is it?
 
It is very sturdy actually. The only worry is the old fork, but with the small frame and tires it isn't getting beat too hard.

I will take apart the hub motor this weekend and check it out. I have basically been running an accelerated wear test. So far I have about 150 miles on the hub at 24s a123, stock nylon gears inside.


I really wish I had not built this bike. I hopped back on my commuter bike- 36v and 26" wheel - and it was anemic on power. I can't go back to a normal hub motor now :lol:




Next up, an Ebike-kit motor laced into a 16 or 20" rim, on double the voltage!! I think it will be a rippin little beast.
 
Reterminated the bafang as Delta and swapped over to a Castle HV110 ESC, 12s Zippy 5ah lipos and a Magura throttle. It has just a touch more speed on the lipo with Delta termination as compared to Wye and 24s a123. I think the batteries do not have as much voltage sag.

The HV110 with Magura is butter smooth. No more crazy sensitive throttle, I can stand up and just about control wheelies after a bit of practice. Talk about night and day difference.


I have a 4pdt on there for Delta/Wye switching. It is more like a suicide shifter right now, but the Wye termination is very nice for going up hills with no worry about heating up the ESC or motor. The ESC runs wide open so it stays cool, and the motor won't pull many amps chugging along at about 10mph in the 16" rim. My pedal cadence and gearing is perfectly matched for it going up hills too. I really like having the termination choice now :mrgreen:
 
Stole the parts again for another reincarnation :lol:

Soldered the Bafang into Delta mode permanently since the 16" tire is pokey slow. Currently running a 20a 6 fet controller and 12s 10ah lipo. I made this bike small so I could throw it into the trunk and use it as the last mile rider. Just a different mix of parts I had laying around.

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I gathered some parts for the next build today. The electrics are getting swapped over to the new setup, and the front hub is being added for 2wd. I am thinking of using my main commuting pack on this, and just using a harness to drop it down to 10s4p lipo for the wee little bike. Would make things easy for me.


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New mini project in the makings. The purple bike from the last post has served very well for over two years now, but now I want something nicer. The batteries are getting saggy so it is perfect time to plan the next incarnation.


The plans started out as another mini bike, but the more I plan the larger the bike gets. I started at 30" wheelbase, now we are looking at 36" wheelbase so it feels like a bmx (which is rather comfortable in seated and standing positions). The above photo shows a scale drawing with 30" (top) and 36" wheelbase.


Parts list already purchased:
Risse Racing Trixxy BMX forks (135mm OLD)
AllCell 48v 20ah battery
head tube and headset
headlight
12" mini moto rims
12" shinko 241 tires

Steering geometry has already been figured at 30 degrees rake, which will give about 3" trail at full extension and 1.5" trail at full compression. A local motorcycle frame builder has offered his assistance with building the jig and frame, so I'm going to ride his coat tails as much as possible :lol:


Now comes the tough part. Originally I planned dual hub motor with some Bafangs. Lower power @20mph, but great handling off road and a bit more novelty. But the more I think about it, the more I lean towards a motor in chassis driving the rear hub at higher power @ 30mph so it is more useful to zip around with. I have a floor buffer motor that would gear perfect into the small wheels. I could also put a Puma or 9c in the chassis.


What says the sphere? 20mph dual hub, or higher power mid drive?
 
It would offer a higher power to weight ratio, and I really want to keep the bike as "trunkable" as possible. I'm also a bit concerned about how hard we will be riding the bike, and how little hub motor axles would handle the stress. The only way to be sure the bike will take jumping and 300lb rider abuse is mid drive.


So maybe I will build a dual hub mini bike for golf course and party fun, and build one bmx sized bike for serious trail shredding.
 
How is the moped shop going John?

I like how you can hide the batteries under that big ass seat on the purple My Little Pony Bike.
 
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