This instructable explains how to save two old bicycles from the grave to create one immortal tandem bicycle.
I had always fancied building something for fun and actually dedicating a bit of time to a project rather than just the odd quick fix here and there. With a charity bike ride looming a couple of months away it seemed like a great idea to try to build a tandem and enter it just for fun. A few friends and I had entered the event the previous year dressed as glam rockers and it got a good response so we decided to repeat it this year. (Hence why this tandem has a bit of a Gothic look to it!)
I had never ridden a tandem before and didn't really know what I was aiming for so I looked online at some different frame designs to gain some inspiration. I decided that I didn't want my bike to look like two bikes - I wanted it to look like a genuine tandem frame. I also learned that having a decent spacing between the driver and passenger was essential to ensure that the passenger could actually see some scenery and not feel too cramped on the back. Throughout this instructable I refer to the driver as the 'captain' and the passenger as the 'admiral' because this is proper tandem lingo dontcha know!
This bike cost very little to build as most of the existing components were cleaned up and reused. The only parts bought new were bearings, chains and cables. The only really specialist tools I used were a bicycle chain tool (cheap) and a MIG welder (err, not so cheap)
Tools you will need:
- A pair of grips
- A pair of pliers and cutters
- Allen keys and spanners (various sizes depending on your donor bikes)
- Hammer/Mallet (for persuading stubborn bike parts to come off)
- G-clamps or large magnets (for holding the frames together when welding)
- Angle grinder (with cutting disc and grinding disc if possible)
- Metal hole cutters (you could use a hacksaw and then file the tubing to shape but this takes a LOT of time)
- A pillar drill (a pillar drill is ideal in order to cut the angles more accurately but a similar result can be achieved using a hand drill and a jig)
- Bicycle chain tool
- A MIG welder - or gas/TIG if you have one available!
- Some wood to make up a frame jig prior to welding
- Spray paint (primer and colour)
Other things you will need:
- Some old bikes! (Free)
- Piece of mild steel tube (from scrap metal yard £10 / $17)
- Paint (£25 / $40)
- Bearings and cables (£10 / $17)
- Chains (£7 / $11 each)
Step 1: Donor bikes and Dissembling
First things first - you are going to need some donor parts. By using some old bikes that were destined for the bin; a) they were free and b) this project incorporates recycling in its purest form : )
The donor bikes were sourced for free – I found two in a skip and the other in the garden of someone’s house. (I did ask before I took them!) I figured that the third bike would come in handy for some extra spares should I need them. All three were in a pretty sorry state and rust had got to most of the components.
The fun begins by unbolting everything from the old bikes. You won’t need much in the way of specialist tools for this although a chain tool is essential for breaking the chain and will come in handy later on when the new chains are to be sized and fitted. A crank extractor tool will also make it a lot easier when removing the crank arms from the bottom bracket but this is not essential. If you've got a wooden mallet and a good shot then hit the cranks hard and they will come off eventually. It ain't pretty and I wouldn't advise doing this on anything other than an old bike where the frame is steel and the cranks are massively over-engineered! Basically don’t go trying this on your carbon cranks! : )
To remove the bottom brackets I used a pair of water pump grips to get the bearing cups out of the frame. You need to remember that one side is a normal thread (undo by turning anti-clockwise) and the other is a reverse thread (undo by turning clockwise). This also applies to the pedals where they bolt into the crank arms but I will go in to more detail on this later.
As you can see the bearings looked like they were due a bit of a service(!!) Due to how badly corroded they were. I scrapped them in favour of some nice shiny new ones. I also cleaned all of the cups out with sandpaper and a wire brush so that the bearings could glide around happily in some slimy new grease.
If the brake and gear cables look in good condition (shiny metal and not frayed) then you may wish to reuse some of them if you’re doing this project on a budget. In the interests of safety and smoother braking/gear changes I’d suggest you replace them all as they are very cheap and it means you don’t have to waste time undoing the old ones – snip, snip!
To remove the forks, undo all headset bolts and the steerer tube nut (the nut at the top of the forks where they clamp onto the handlebar stem). You will then be left with two bearing cups in the head-tube of the frame (top and bottom). To remove these you can either use the proper tool (boring!) or get a wide bladed screwdriver and tap them out gently with a wooden mallet ensuring that you tap equally all round the bearing cup to prevent it getting stuck at an odd angle. Also be careful not to damage the surface where the bearings sit.
Everything else will unbolt from the frame with spanners and Allen keys. Eventually you will be left with a tray full of rusty bits, a couple of old frames and some well used wheels!