Monday, 18 January 2016

Thorpy's Guide to Bicycle Sidecars

Thorpy's Guide to Bicycle Sidecars - Intro

This sidecar project is a follow on from my DIY Long Tail Ebike which I think was nor very reliable of useful. The main problem was the drive system, where the rear sprokets kept coming undone during use owing to a reversed thread.

Sidecar for Bicycle. Mixed Results.

So how to get around this? At present I have the pedal chain and the motor chain driving two sides of a flip flop hub, so one thread in the wrong way around. By adding a second driven wheel to the sidecar perhaps this would fix things. No it won't. But I present my findings anyhow.

Thorpy's Guide to Bicycle Sidecars - Research Summary

I know nothing of sidecars, so I did a bit of read on the web first the main thing to realise is that a bicycle side car will need to hinged. Other wise you bike will probably fall over going around corners. A sidecar on the left of the bike for example that is not hinged will result in rubbish left hand cornering, as you will not be able to lean in to the corner.

The only non hinged bicycle sidecars that you see are either the BMX racing ones (where the sidecar is presumed to weighed down with a human whilst riding) or the taxi type things they have in the Philippines (which are named after King Philip of Spain by the way).

So in short unless you side car is heavy or permanently loaded then you will need a hinge.

Thorpy's Guide to Bicycle Sidecars - Motor Driven Wheel on Sidecar

So with nothing but I skewed common sense to guide me I built the side car, welded it on, use some heavy door hinges (steel not brass!) I mounted the motor and went for a test drive.

Note Mounting Plate for Motor
The result. With a hinged sidecar there is not enough down pressure on the wheel to create adequate traction. Of course when loaded this would work OK, so if you had you side car mounted with big heavy seat or a heavey wooden box, this approach may work. It didn't for me.

Thorpy's Guide to Bicycle Sidecars - In Use

So since this first failed attempt I have switched the motor on to the front wheel to make a front wheel drive chain driven ebike. This has proved a really good move, and I now have a reliable drive system. But I thought I would test out how usefull the sidecar was being I had gone to the trouble of making it.

So apart from the extra width when empty you would not even know the side car was there, the bike corners as normal, and when the hinges move the tire moves in and out from the bike  slightly, which you think would be noticable but whilst moving it isn't.

Right Hand View

BUT what about when you load up the sidecar? Oh dear. I put 50 kg - 60 kg of logs in sacks in the sidecar, and things went wrong. Now there is a greater deal of pressure on the sidecar wheel, and as a result the friction with the road is greater, the hing effect is now very "sticky" and this had some "interesting" effects on steering.



Something that is also perhaps a bit dangerous is that when you turn right the cargo bed widens, and loose sacks of say logs, will slump down in to this new widened space, and you will not be able to get the bike upright.

The ONE thing that is good, is that the bike will stay upright when you are loading it, although you have to be careful not to knock it over.

Thorpy's Guide to Bicycle Sidecars - Recommendations

Some really big spring in stead of hinges might be an idea. So you bend when going around the corner, and the hinging effect is limited.

I have seen design with a stabalising bar that you can use when loaded, and take off when empty. Best of both worlds.

Side Car Size Based on Euro Crate Size 400 x 600mm

Rear Dropouts Made from Plate Steel
 A side car seems to bring all of the disadvantages of a car, with all of the limitation of a bike. So Is not really very good. It would be OK for large light loads, but so would any long tail cargo bike + ratchet straps.

A sidecar would be useful for a permanently loaded application such as a rickshaw with heavy seat and canopy, or perhaps some sort of micro coffee kiosk. But for the occasional /one way cargo carrier it represents a world of confusion.

I will be hack-sawing this off in the next few days.

Environmental Consultants London


  1. Thank You for posting this. I consider buliding sidecar on a hinge for carrying moderate heavy loads and I did not consider that hinge + extra weight will disturb steering. I came across one design which seems attractive and now I see that there is shock absorber ... not for the comfort of passanger but for stability of the rider:

  2. Hah, this is a good video. Thanks for sharing. I think a fixed sidecar is best. But it need weight on it all the time.