chain derailment is one of the biggest issues plaguing mini bikes. especially bikes with rear swing arms and there are a few ways to fix it. one very common way is to make a spring loaded tensioner. solid tensioners are also common but only really work on hard tale bikes. The problem is even the best tensioners fail to stop a derailment every once in a while. I have been looking for a better solution and have spotted 2 ways to fix this. Derailments usually start at the rear sprocket so keeping that one in line should solve most of them. at a local mini bike race I spotted a bike with 2 round plates mounted to the rear sprocket just wide enough for the chain to run threw. this keeps the chain from jumping off solving the issue this wouldn't be hard to mass manufacture a nice looking, light weight version but for me at my current skill level, this would be hard to copy and would be heavy and look ugly.
While looking at a dirt bike for answers I spotted the second way and its so easy I'm shocked mini bike manufacturers haven't picked up on it. they created a chain guide almost like a bicycles front derailleur but beefier. Its placed right in front of the rear sprocket. Its 2 metal plates each holding a Teflon plate on the chain side with a gap in the middle and its bolted to the swing arm. the chain passes threw the gap in the protective Teflon onto the sprocket. This device prevents enough movement to keep the chain from derailing. this idea looks easy enough to copy so I'm going to try it. I looked at the price of buying one from a dirt bike to modify for my mini bikes but they use much wider chains and the prices of new ones just weren't reasonable. The only issue I can see with this idea is having to occasionally replace the Teflon which should be easy enough. I'm a very busy person so I may take a while to build one but I'll update you guys with the results once I do. If this idea works all my bike will be getting one.
While looking at a dirt bike for answers I spotted the second way and its so easy I'm shocked mini bike manufacturers haven't picked up on it. they created a chain guide almost like a bicycles front derailleur but beefier. Its placed right in front of the rear sprocket. Its 2 metal plates each holding a Teflon plate on the chain side with a gap in the middle and its bolted to the swing arm. the chain passes threw the gap in the protective Teflon onto the sprocket. This device prevents enough movement to keep the chain from derailing. this idea looks easy enough to copy so I'm going to try it. I looked at the price of buying one from a dirt bike to modify for my mini bikes but they use much wider chains and the prices of new ones just weren't reasonable. The only issue I can see with this idea is having to occasionally replace the Teflon which should be easy enough. I'm a very busy person so I may take a while to build one but I'll update you guys with the results once I do. If this idea works all my bike will be getting one.
