The question is the topic, I’m mounting a 79cc predator engine to my longboard, I have both trucks moved and placed in the front of the board for stability and weight( turns like a beauty, only I replaced the back end of the board with a modified form and added a small bike tire to the back with a larger sprocket for higher top speed, only I have no clue what size chain I need to put on there, I heard #40 but I feel like I’d have clearance issues with the tire( its wide for grip and stability) so I just need STANDARD WIDTH 1/2 inch peak chain size. No heavy duty stuff cause I only have as sprocket I ripped off a BMX welded to a metal ring directly to the wheel.
Bicycles suffer a ridiculous degree of parts incompatibility across brands, countries, and eras, so any sight-unseen advice would be shaky, at best. Just take it to a bike shop and get manually fitted.
Where I live there isn’t a single bike shop within 70 miles or I would have done that by now, I could order a chain no problem only nobody seems to know the actual chain specs. With that its no issue. I understand roller chains come in multiple sizes and that an example of this is that a mountain bike chain is slightly thinner due to the derailleur. A bmx chain and cruiser chain is the same width but it does me no good if I order a heavier chain, as the sprockets may fit fine from one sprocket to the next but I can’t have the chain rubbing or shifting side to side because; one. Its a longboard. Two. My gear ratio will have me traveling at over 45 mph on a single gear. And three. If the chain slides or even worse slips off because it has too much play than ill likely be hospitalized or six feet under the moment it happens because longboards turn so sharp the force of the chain slipping or moving around alone can cause Me to spin out and crash. And added insult to injury is that the sudden loss of resistance will increase my rpms so high my brand new predator will be toast, on top of the torque converter, compressor, intake and filter are right by the chain as well cause I remodeled and had to reduce the overall space taken on the engine, I have new lifters and clutch as well. Lifters are cheap but the clutch kit is expensive. The work and money and time I spent building this is something I can’t risk damaging the first time I use it.
The Wikipedia article on bicycle chain list 8 different widths for 1/2" chain. I think you need a dial caliper to measure your cogwheels.
Dennis
1/8" is the most common width for single-speed bicycles. See here, here, and here among other cites.
Removing or installing chains on a single speed bikes is pretty simple. Maybe you can find someone who will lend you a chain for a day for fit?
There is compatablility one way and not the other. The 1/8th inch chain will fit on a chainring meant foe a 1/8th inch chain or a chainring that is designed for a 3/32 inch chain. I don’t understand most of what you’re saying in your post, but if you are using a BMX cog/freewheel, an eight inch bicycle chain is your most likely bet - unless the BMX bike was something really obscure or eaten by rodents or something weird like that.
Measure the sprocket with calipers. Tooth center to tooth center will tell you the pitch and the width is a direct measurement. Chains and sprockets are made to match, so once you know the specifications of the sprocket, you will know what chain you need.