Friedlbug's e-bike build thread
 

OK, I've decided on the design of the e-bike I want, and I will be building it. The motor is in route to my home and I obtained a free 10-speed today. Progress!
Free Murray "Explorer" 24" 10-speed (24" is the right size for me):
http://i18.photobucket.com/albums/b1...bikebefore.jpg
The frame fresh from the Goo-Gone treatment (fingernails, Goo-Gone, elbow grease, and an old sock):
http://i18.photobucket.com/albums/b1...lbug/frame.jpg
The Bosch 24V 350W DC permanent magnet motor on the way (old but unused - $20 with shipping on ebay):
http://i18.photobucket.com/albums/b1...lbug/motor.jpg
Here are links to the design:
http://autospeed.com/cms/A_2419/article.html
http://autospeed.com/cms/A_2421/article.html
http://autospeed.com/cms/A_2430/article.html

Looks good so far, excited to see your progress!

I'm watching as this is something I want to do when the 15 feet of snow start melting here.

why did you choose a 350 watt motor? Bosch seems to make good motors, so I suspect it will have more real life power then most 350 watt motors, but I still wonder what your top speed will be.
also, any idea on how you are going to connect it to the drive wheel? speed controller?

This looks very interesting. Looking forward to watching the progress.

I got the 350 because it seems that's about the most that can be gotten from 24V using practical amounts of current. I want to stay with 24V because I like the plan in the Autospeed links at the bottom of my first post (manual, switched speed control with regenerative braking). It will be a friction drive.

No pics yet, but I just finished spraying the frame flat black and stripping the old dryrotted tires and tubes off the rims.

Excuse the lack of experience and proper terminology, but anybody know if new innertubes come with the rubber strip that stretches into the rim and covers the spoke connectors?

Schematic of switched electrical system from the article referenced above:
http://us1.webpublications.com.au/st...4/2430_3mg.jpg

As far as the rim tape you'll have to get that separate from the tubes. Velox is good. Good luck with the project I look foward to following it.

Painted and cleaned up (plus the seat is no longer in the "violator" position):
http://i18.photobucket.com/albums/b1...ug/painted.jpg

I got the motor today and took my first ride on the bike (without electric yet, of course). I have to say that I'm a little annoyed with the motor seller, since the motor came labelled as a 12V motor. There's no reason why I will not be able to use it as a 24V motor for 350W, but it still should have been listed as a 12V or 12V/24V motor. Anyway, the bike after ashort ride:
http://i18.photobucket.com/albums/b1...lbug/bike2.jpg
The motor:
http://i18.photobucket.com/albums/b1...bug/motor2.jpg

Is there any special trick to getting the mended link to not be too tight after closing the chain with the chain rivet tool? I've tried to get the rivet back in just right, but no amount of adjustment seems to get that link as smooth as the others.

I usually flex the chain back and forth in the sideways direction (the way it isn't meant to bend)to loosen the newly pinned joint up.
Hope that helps:)

Thanks for the suggestion for the chain. I'll try it.

As far as the wiring, I found a DPDT switch with a center off position at Radio Shack today and am wondering if I could simplify the schematic like this (not sure if that's the correct way to depict the switch, but it should be logical at least):
http://i18.photobucket.com/albums/b1...simplified.png
Any ideas?

I don't see why that new switch config won't work.

What's the switch rated for? Without a controller to limit current, a switched setup can potentially draw quite a bit of current under stall/high load conditions. Not sure what's typically seen on a 24v e-bike though.

The switch is rated for 20A at 12V.

350W/24V=15A.

20A*12V=240W

Not sure what your trying to do here. Are you working with 12V or 24V system?

I believe its set up so that the 24v gives you the acceleration/cruising, while the 12v is switched on for regen when going down hills.
Correct me if im wrong
S.

That's basically it. The only thing I'd add is a 12V step in acceleration from a pedal start, assuming it has anything to add running at 12V.

Hammer, my point about the switch rating is that I'll be a little under the current rating and twice the voltage rating. I'll test it thoroughly first.

Also, I thought of a problem with using the center off DPDT switch configured like the schematic above: The charging socket won't work - it'll just spin the motor. There has to be a switch to take the motor out of the circuit. Back to two switches.

Thanks for helping me understand.

Here is a pretty sweet homebuild:
http://www.peltzer.net/ebike/
Its got a huge motor & sweet belt drive!
S.

sharp21 - good link. That's a comprehensive look at issues of building an e-bike.

If you want to try a cheap motor controller that gives you variable speed, current limiting, and low voltage protection (to save your batteries), check out these scooter parts. http://tncscooters.com/partsdb.php?type=ES looks like a $12 one might work for you.


The electric scooter I recently aquired uses many of the parts they sell and the variable speed drive is pretty cool and supposedly 95% efficient.

Oh yes, I've checked out the Peltzer e-bike. That's the gold standard of homebuilt e-bikes, in my opinion. He mad his own jackshaft on his own metal lathe and had a much higher budget for batteries than I do, though. I don't think there's any way you could practically use inexpensive batteries to run a 1HP motor like that with any kind of range.

Just a quick update: This has been so slow going because I have very little free time during weekdays, robbing myself of sleep if I want to do anything after a normal day. I did find time to get to Home Depot yesterday, though, and added springs to the frame on each side of the rear wheel (there were these cool little metal loops in just the right spot). I plan to use spring tension rather than the compression method used in the article. They are highly polished extension-type springs with a listed load limit over 30 lbs each. Also, they look pretty cool. I also picked up a 4' length of nickel covered steel angle (the kind with holes all through it) with which I'll make the 'T'-shaped motor mount. I forgot the PVC elbow for the cooling duct, but am not sure how I'm going to mount that yet anyway.

Im thinking of doing a Hub conversion on one of my bikes. FWIW here is a link to a thread discussing the best value kits on the market:
http://bikeforums.net/showthread.php?t=326941
Be sure to check out the links, lots of good info at the goldenmotors forum!
Couple of good leads on (relatively) cheap LiOns too.
Now, should I put this on my beach cruiser, or my barhopper chopper...
http://i45.photobucket.com/albums/f6...ozeCruizer.jpg
S.

Wow, that's super cheap for those LiOn batteries. Maybe once this gets going and I prove the concept to my wife. As far as that bike, it's very nice. I'm not sure I'd want to replace that front wheel, though.

I found a box to mount my switch in today and an 24VDC fan from an old dot matrix printer for the cooling shroud. I sawed some angle to spec out the motor mount.
http://i18.photobucket.com/albums/b1...witchstuff.jpg
http://i18.photobucket.com/albums/b1...artingrack.jpg

It won't be long before your first test run.

Unfortunately, the situation with my Yaris has changed. I now need the bike as a bike and have put my e-bike aspirations on indefinite hold. The last developments were that I mounted the motor to the bracket and connected the two 30 lb springs. The springs proved to be too strong and broke the roller I made.