Lightweight and Inexpensive Gearbox for bicycle

Hello everyone, I've been working on my electric bike drive for some time now and I didn't want to post until I had some pictures to show. Well that time is here, I finally have some pictures and as soon as I get the last few parts in the mail I'll be on the road. I just ordered a ping pack and can't wait for it to arrive.
Here is a shot of the rear wheel which I have added 2 freewheels, a 16T deraileur chain freewheel for the pedal drive and a 20T bmx freewheel for the motor drive.I used a threaded hub and then made a threaded part to screw the freewheels together
The gearbox is almost finished, I'm waiting on some belts and I haven't finished attaching the bearings yet, but I should have it done in about a week.I'm using a .5 HP 3.4 pound motor from ampflow for testing but could easily use just about any motor.
My goal for the first unit was high quality and low cost.

How did you get the two freewheels on the hub?

Bubba

You can stack freewheels using a bottom-bracket cup

Yes, I've heard you can use a bottom bracket cup but I couldn't find one so I made one from 1-3/8 aluminum tube.
I will be selling these on my website soon, but for now send me an email at stub2005@gmail.com and I can send you one.

I'd love to see more details about your construction methods. Looks very clean and simple. I like it a lot. Nice job!

I'd love to see more details about your construction methods. Looks very clean and simple. I like it a lot. Nice job!

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Thanks, I plan to post a parts list and detailed instructions for those who wish to build their own.I will have my website up soon, maybe even tomorrow as I have the day off

mud,

Well done.

Your gear box is a similar concept to the one Matt has in the pipeline, (his is more of an endostructure and yours is more exo...).

I like the design!

May I offer one suggestion?

The XL pitch belt you are running will be great for the first stage. However, I can pretty much guarantee it will skip on the second stage. You may want to move to a 5mm HDT or powergrip belt (15mm wide) for your second stage.

Other than that, it should work great.

Matt

You know someone knows their stuff when they can look at a 600px image of a few pulleys and know their pitch type and size

Mud, have you looked in to R/C motors at all? They seem to be a perfect candidate for a final motor in your design.

May I offer one suggestion?

The XL pitch belt you are running will be great for the first stage. However, I can pretty much guarantee it will skip on the second stage. You may want to move to a 5mm HDT or powergrip belt (15mm wide) for your second stage.

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Thanks for the advice, I'm researching the HTD and powergrip belt drives right now, shouldn't be difficult at all to swap out the current pulleys for HTD. I'm definitely going to do that. I just got email from ping while posting this that my battery has been shipped

Mud, have you looked in to R/C motors at all? They seem to be a perfect candidate for a final motor in your design.

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I am constantly shopping for motors and I do like many of the RC motors out there but have yet to decide on which to buy. I have owned astroflight 40 cobalt motor for an electric skateboard project and was impressed with the quality but it comes at a cost. also they are lightweight but run at high rpm. I decided to go with the ampflow for now as a compromise between cost weight and power. Its not hugely powerful but its only $80, its not the lightest at 3.4 pounds but it runs at 4000 rpms. also I think I can run it without a speed controller just an on/off relay switch which saves $$ also. I will find out soon if I'm right on this as I haven't tested it yet.

Cool.

I don't mean to criticize your design at all. I am always thrilled when I see guys making stuff from scratch. I just want to save you one R&D step. :wink:

Looking forward to seeing it all together!

Matt

I don't mean to criticize your design at all. I am always thrilled when I see guys making stuff from scratch. I just want to save you one R&D step. :wink:

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Don't worry I totally value your input, I have seen your website and am very impressed with your work. The electric recumbent looks like a lot of fun to ride

I'm actually thinking about switching to #25 chain to the wheel, and just using a single stage gearbox for now. That would eliminate any chance of slip and overall construction would be simpler. Time to hurry up and wait for more stuff in the mail

Hi mud- I have stopped using non rollar chain- #25 and #35 both only use lube on their surface that pickes up all sorts of
grit from the road, which eats the sprockets and chain.

The 2 bikes that I have that chain on I have added a shield that helps a little, but they have to be lubed often.

The bike chain, and #41 is what I have been useing on the newer assemblys.

I have cleaned the rollar chain well-with solvent, dryed, folded up alumium around chain to form a cup, poured in 90~ weight
synthetic gear oil to cover, put in a pressure pot, capped- applied 15psi air to force in lube, remove, wipe off outside surfaces,
install.