Critical failure caused by chain tensioner

R

ratman150

New Member
(grrr can't hit tab, got so used to MLA formatting from school)

Alright so, got my bike, built it, got it started....Rode it for roughly 2 minutes, my dad talked me into moving the chain tensioner a bit to keep it from the wheel. Rode maybe 200 feet and back, right as I pulled into our driveway and was ready to kill the engine...The chain pops off engine catches it cracks the clutch case top mount ruins my clutch.

I can take partial credit for this failure, I meant to tighten the rear wheel properly but got distracted by my dad. Part of this is due to the wheel flexing and thus causing the chain to come off the sprocket. However, I will redirect you to my question.

TL; DR version; I am having problems with the stock idler wheel, which is destroying itself and need some suggestions. I plan on running high compression heads soon so spring mount isn't ideal but optional.

Bit about my bike, standard walmart grade Huffy Beach Cruiser (Blue), the half white wall back tire with the black marks on one side. (I'll post pics soon, probably after work of the failure and the engine mount).

I have plenty of tools at my disposal so if it comes to it, I can design my own idler, which I'll make plans of or make available for purchase if I do...I just cannot stand the plastic "self shaving" idler.

Part of the problem appears to be the chain is so tight that it just destroys the plastic instead of using it to idle on top of.

/endhalfrant
 
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In my own experience; if you install the chain properly and align those sprockets, the idler will last longer than your engine(s). Too tight a chain will negatively affect performance and cause premature wear. I say FORGET about high-compression heads, and any other performance-enhancers until you get the basics down. I suspect that you're much lighter than me (my bike carries me and my backpack...about 330lbs), and my standard 66cc gets my ass around pretty quick. I imagine someone of average weight could get about 35MPH outta it. I've maxed at about 30MPH...cruise at 25MPH.
 
Kioshk said:
In my own experience; if you install the chain properly and align those sprockets, the idler will last longer than your engine(s). Too tight a chain will negatively affect performance and cause premature wear. I say FORGET about high-compression heads, and any other performance-enhancers until you get the basics down. I suspect that you're much lighter than me (my bike carries me and my backpack...about 330lbs), and my standard 66cc gets my ass around pretty quick. I imagine someone of average weight could get about 35MPH outta it. I've maxed at about 30MPH...cruise at 25MPH.
Click to expand...
Ditto:

Concentrate your efforts, and your money on building a safe reliable bike and mastering the basics, such as chain/sprocket alignment and tension. Leave the go-fast parts for later.

Tom
 
Your dad is right about placing the tensioner to close to the sprocket, all that chain wrapped around 3/4's of your sprocket causes a lot of drag and will wear out your drive train sooner,and have a negative effect on performance too. If your chain tensioner is properly located and correctly aliened it will cause very little drag and wear very well. My frame is wide and I had to shim the tensioner wheel inward to line it up with the sprockets.
 
you could just get rid of it. i haven't found a bike yet that i needed to use a tensioner on.
 
This is what I used on mine, 10 tooth metal idler mounted on the stock bracket that came with my Grubee GT5 SuperRat. I think it's aluminum, magnet won't stick to the teeth. Sealed needle bearings for long life. The original plastic idler wheel that came with my kit didn't last 500 miles before shreading. This one has about 2000 miles on it & is still good. You can get yours here at Pirate Cycles: http://www.piratecycles1.com/10tprbeidsp.html
 

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