Tuesday, 24 November 2015

DIY Long Tail EBike - Chapter 4

DIY Long Tail EBike - Chapter 4 - The Final Chapter


So its been a while since I posted chapter 3. Its one thing to build a long tail cargo bike or long tail cargo e-bike, but whether it works or not . . well that takes a few months to find out.

Below are described the "few" teething problems and remedies that I have stumbled upon over the last few months. Also a few fatal flaws in the concept . . .

DIY Long Tail EBike - Chapter 4 - Drive Train

You will see chapter 3 that that I have a flip flop set up (more of a flop flop set up really) with the electric motor on one side and the pedals on the other. 

Chain Tugs and a Large Rear Sprocket - Essential

I found that the gearing for the motor was too high, and it was not running at a high enough RPM on hills, so I have added a 24 tooth free wheel (ebay), to lower the top speed and increase torque. You might consider going a bit bigger. Head over to TNC Scooter Parts to find all sorts of handy sprockets etc. Just be sure to get the right gauge!

The next niggle was that the ultra strong loctite used on the non-reversed threads was not strong enough. So I have had to opt for epoxy there. 

Last drive drain mod was to add some tug-nuts / chain tensioners on the slot drop outs as the rear wheel kept moving, this is understandable as you are imputing nearly twice the load (you pedaling and the motor). It also helps with tensioning the chain correctly.

Reversing the drive side of the bike i.e. chainset and sprocket (for pedals) on left hand side of bike. Is . . . problematic. Not only is the sprocket thread now the wrong way around, but also the pedals.  

Most of the problems I have had with this bike. In fact 99% of them could have been avoided by using a hub motor. USE A HUB MOTOR!

DIY Long Tail E-Bike - Chapter 4 - Lights

Hah! The headlight is serious overkill. Splashes light all over the place. So I had to add in a smaller side light so I could switch the headlight off when cars were approaching. 

Monster Headlight / Sensible Side Light . . .
Introducing this side light meant using a switch. To toggle between them. Ebay again held the answer. The switch is an engine kill switch for a quad bike of similar.

Switch for Side Light and (more importantly) "Captain Shakry" Squeaky Hooter Thing

DIY Long Tail EBike - Chapter 4 -Seating

Unless you want your kids to fall off on to the road, then they will need some handles. I have arranged this by using some rope threaded through some 15mm water pipe, and then hole drilled in deck to fasten with a big knot. All very technical.  

Some padding is a nice touch too. Find some bubble wrap or foam and wrap in cloth, then use a staple guhn to attach to the wooden deck.

Handles for passengers. Quite . . . handy. Sorry

DIY Long Tail EBike - Chapter 4 - Useability

I am sorry to say this bike will not get used very much. Here is why:

  1. Wrong Frame. If you base a cargo bike a on a BMX it will start out not very ride-able. After all BMX bikes are not meant to be ridden long distances. The rear drop spacing are not likley to accept a hub for gears. 
  2. Complex Drive System. The choice of drive system. A hub motor would allow you to have some gears, and maintain a normal right hand side drive setup at the rear. Sooooo much easier.
  3. Not Powerful enough. In the UK the 250W power limit is too low. What is the point. I get sweaty riding this bike, and it has a limited range probably about 15 miles. My "normal" cargo bike will go all day if I am supplied with pies. 
  4. It is heavy. It must weigh 40 kg without a rider or cargo, so you can only really turn it around whilst rolling it (you can pick the front end up and swing around but this requires a large turning circle).
  5. It is noisy. Wrrrrrrrrr. I like to be able to talk to my kids as we wizz along the country lanes. This is somewhat spoiled with the noise from the electric motor. 
  6. No Luggage to Fit. The wide rear deck, and short distance to foot rests means that panniers will not fit.EDIT: You could add a bicycle side car, for luggage space.

DIY Long Tail EBike - Chapter 4 - Hints for Prospective Tinkerers

1 - For the love of crumb cake. Please use a hub motor on the front wheel.

EDIT: Or move your chain drive motor to the front wheel, it is a lot easier, especially on a BMX!

2 - Even with a BMX Frame, you could still have 3 widely spaced gears by using a 3 ring chainset (with shifter and front mech) up front. Mount a rear derailleur for chain tension only. I was planning to do this and may do in the future. 

3 - Use an MTB Frame

4- Use the online calculator to work out if you can build a bike with useful range. 

5- If you are not using a hub motor. Then really pay attention to the chain and sprocket gauges.

NOT FINISHED - FURTHER "IMPROVEMENTS".

I moved the motor on to the front wheel in the end. - Front wheel chain driven ebike.

I also tried a side car for a time. - Thorpy's guide to bicycle side cars.

DIY Long Tail EBike - Chapter 4 -  Two Years On

It is around 2 years now since I completed this long tail e bike, and I have been improving it over that time so as to make it as good as possible. 

"Nearly Finished"
So what has been attempted.

Cushion on Rear Seat 

This was made with some foam, and black fabric, which I then used a staple gun to attach the wood deck at the rear. 

Lights

This took a while to get right, choosing an e bike headlight is tricky just because there are so many options. For a short time, I fitted a very bright light, but you do not really need this. A 3W LED head lamp is probably sufficient. 

A rear light can be found on ebay for not much money. LED lights are preferable. 

Speed 

I only have one gear on this bike, and that has caused a minor problem in that is is difficult to match you motor speed with your pedal speed. I have successfully used a 3 speed switch , to slow the motor to match pedal speed.

Of course setting you gearing correctly is important. For 15mph speed I have opted for 46 teeth front chain ring, and 14 tooth rear freewheel. 

Tires

The smoother the tire the less energy will be wasted, if on roads, so unless you are going off road a lot then opt for a semi slick tire. These provide a smooth center ridge, and so knobbles on the side, this is important as if you do ride a heavily laden bike on a side slope, if it slips you will have to be very strong to stop it.

On this longtail e bike bike both the rear and front tires are difficult to remove, if you get a puncture. I have installed so tire slime, and it has worked very well, I have not had a puncture since!

Luggage

If the rear seat is taken up with children, then where do you put all of the bags and stuff? Well upfront would be the obvious answer. I managed to fit a front rack. Steco do some good cargo racks, which would do the job well. 


6 comments:

  1. Good, honest, write up.
    What's the next project?

    ReplyDelete
    Replies
    1. That's how I roll. Cheers for commenting. Must pop over and have a squiz and 2nd Gear sometime!

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  2. I saw a hub on line somewhere that has the shimano spline in both sides of the hub so that you can mount a sprocket on both sides without threads undoing. On my Cargo bike I went with a mountain bike frame and used a triple crankset and the biggest acera cassette on the back wheel (20") that I could get. It does weigh a lot as you mentioned with your bike but I find the easiest way to move it around is to ride it.
    P.s. I always get sweaty riding it (Queensland Australia) (No Assist)... But I luv it.

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    Replies
    1. Thanks +Jason Nielsen on my normal cargo bike, I have gearing similar to yours. And it is fine. A 20" rear wheel would be mint for lower gearing. On my normal cargo bike, if I am carrying "stuff" it is normal bulky and light. If carrying kids I get them to walk up the steeper hills, and save dad's knees! I have googled the $h1t out of dual sided hubs, and had little result.

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  3. I saw a hub on line somewhere that has the shimano spline in both sides of the hub so that you can mount a sprocket on both sides without threads undoing. On my Cargo bike I went with a mountain bike frame and used a triple crankset and the biggest acera cassette on the back wheel (20") that I could get. It does weigh a lot as you mentioned with your bike but I find the easiest way to move it around is to ride it.
    P.s. I always get sweaty riding it (Queensland Australia) (No Assist)... But I luv it.

    ReplyDelete
    Replies
    1. Queensland Australia! I sweated my a$$ off while we were there and that was in the winter. Good effort I say to you.

      Delete