I've been cleaning (de-hoarding) my shop in an effort to gain some room. I came across a box of bicycle parts and noticed one of the several old Freewheels in that box had a 15 tooth sprocket and another one had a 30 tooth sprocket. Perfect for use as a timing chain! I proceeded to rip them apart in an effort to salvage those two sprockets. I had to use destructive disassembly techniques on them. They were never designed to be dissembled. The smallest sprocket was threaded on the hub with some sort of permanent thread locking compound. I used a grinder to cut it off the hub. Lucky for me I had no use for it because it was worn out and had an incorrect tooth count. I salvaged the 15 tooth sprocket from that Freewheel and used the same destructive disassembly technique on the Freewheel with the 30 tooth sprocket. Here is a picture of the "liberated" sprockets.
You'll want to use new 3/32 (Multi-speed) bicycle chain which costs about $15 at Wally World or that Bulls Eye store.
Before you make the effort to salvage your own bicycle sprockets make sure the sprockets you want are not worn out. Some people pick a ratio they like and never shift gears on the bike. Consequently all the other sprockets will be like new just like the sprockets in the above photo. Adapting them for use on a crank shaft and cam shaft is easy. Just turn the outside diameter of a hub to the same internal diameter of the sprocket leaving a shoulder ensuring the sprocket does not wobble after spot welding the sprocket to the hub.
In Bicycle terms the multi-sprocket assemblies used on the rear wheel to provide multiple gearing ratios come in two forms. Older and modern "cheap" bicycles use what is called a Freewheel. All the sprockets are attached to a ratcheted hub that threads on the wheels hub. This assembly of sprockets on a Freewheel are not designed to be repairable. The other type of multi-sprocket assembly is called a Cassette type. The sprockets are designed to be removed from the hub and worn sprockets replaced individually. Cassettes cost a lot more than Freewheels. You'll also find that ordering replacement Cassette "Cogs" will cost the same or possibly more than real timing sprockets from McMaster-Carr.
You'll want to use new 3/32 (Multi-speed) bicycle chain which costs about $15 at Wally World or that Bulls Eye store.
Before you make the effort to salvage your own bicycle sprockets make sure the sprockets you want are not worn out. Some people pick a ratio they like and never shift gears on the bike. Consequently all the other sprockets will be like new just like the sprockets in the above photo. Adapting them for use on a crank shaft and cam shaft is easy. Just turn the outside diameter of a hub to the same internal diameter of the sprocket leaving a shoulder ensuring the sprocket does not wobble after spot welding the sprocket to the hub.
In Bicycle terms the multi-sprocket assemblies used on the rear wheel to provide multiple gearing ratios come in two forms. Older and modern "cheap" bicycles use what is called a Freewheel. All the sprockets are attached to a ratcheted hub that threads on the wheels hub. This assembly of sprockets on a Freewheel are not designed to be repairable. The other type of multi-sprocket assembly is called a Cassette type. The sprockets are designed to be removed from the hub and worn sprockets replaced individually. Cassettes cost a lot more than Freewheels. You'll also find that ordering replacement Cassette "Cogs" will cost the same or possibly more than real timing sprockets from McMaster-Carr.
