Safety Chain Tensioner Idler related accidents

The star nut-washer-star nut-axle nut combo worked good. Either it only moved once, or the new chain "stretched" just a little during the first couple rides (likely).

I just bought this KORE Chain Reactor Chain tensioner at http://www.ebikestop.com /Contact_Us.php for $26 plus $10 shipping including shipping for 2 KMC Z chains!

Its a click-n-mortar store in Colorado, the mountain bike state.

Maybe now we're getting somewhere. I don't know why Grubee can't just sell something like this. I know somewhere you can buy seat tube mounted spring tension rollers similar to this, but I haven't found them yet.

This looks like it will finally be my solution for optimum chain tension.

I ordered 6mmx1.00x75mm machine screws (threaded all the way down to head) from Fastenal Inc at about $1.50/each.

I am going to use one screw in the top right corner, to replace the long screw (where chain cover mounts with lock nut). With this long screw, I can tighten with locktite, then add 1 washer, a plastic bushing, the roller arm mounted over the bushing, another washer, a nut and a locknut. The spring will have to be modified a little to fit a small drilled hole in the driver gear case so it can pull down on the arm. I'll take more pictures next week after assembly, and will have a few extra screws for buddies.

Notes: I have a Madwagon beach bike with the fat tubes. I used the stock mount on the seat tube with no shims. The roller arm will be close but not touching the seat tube. If you have thin tubes (chinese 10 speed, old style mountain bike) you should have a good clearance, otherwise you might have to file the metal on the arm (where the screw goes through the tube), or on the back of the gear case a little.

The KORE chain reactor does not work with MB's. (It can work well on the pedal side for a multispeed bike, to prevent chain suck or chain slap, but does not work on the motor side).
I have a brand new one with packaging and instructions for sale. I put it on the frame but did not tighten any nuts or scratch it. It cannot work with the high mounted motor's chain line (does not go over the chainstay like a regular pedal chain).

It would be in the spokes. It can't fit.

The product looks nice though, and with some Loctite, should be a safe and durable product as intended, for a multispeed bike. Does not work for converting a singlespeed either! (some might say it does, but the package says its not).

Please excuse me. Castellated nuts are for automotive use, or some motor applications. They have cuts on them like the walls of a fort in a crude drawing, and use cotter pins to lock them.

I was talking about track nuts.

happycheapskate said:

Quick release skewers work by cam leverage, and can hold just as tightly as axle nuts. The problem is the axle is weaker and subject to bending under heavy stress (clydsedale riders, jumping, motors).

If you can find castellated nuts for your axle, you can very easily get a tight grip (they are nuts with attached washers, allowing the nut to rotate while the washer is still against the frame dropout. You can also use knurled washers if you can find them, for the same purpose. Smooth washers will move.

Click to expand...

Finished making home made spring tensioner

I rode it 4 miles so far, works great.

I used the special order screw (have 3 more if you guys want one, PM.) and loctite, and the Tractor Supply Co roller arm. I used a piece of vinyl fuel hose for a bushing, and a small washer, and 2 nuts leftover from the motor kit as jam nuts. The very hard part was bending the spring to fit. I drilled a small hole in the case about 1 cm from the edge for the spring to pin against the case for torsion.

Perhaps someone can figure a better way to bend and fit the spring or a better spring to use.

quick link/master links can cause binding

I have a KMC Z chain which is nice. I've always had good luck with these chains on any 1x1. But the small driver cog on the engine side does not like the master link.

I rode for 40 miles today, and the chain jumped 2 times. One seemed completely due to a huge pothole at 10mph when I accidently goosed the throttle. The other occurred while pulling uphill at low speed. The chain slackens to the degree possible if the torque of the engine vs the speed of the wheel, can overcome the force of the tensioner.

I moved the wheel back to just under as snug as I would run it with no tensioner. This seemed to do the trick all the 20 miles back home, but I'm still going to put a normal link in place of the master link.

If you use a spring powered roller on the top run of chain, pull that sucker HARD. All the time you are motoring forward, the chain will be at slightly less tension than that.

Perhaps a stock type idler wheel and bracket (weld it! ) plus the chain tensioner I made, would be tops.

tsc tensioner with #41 idler

Happy,This is on that I made out of a tsc tensioner,it mounts on the seat tube.I have brass bushings in two areas so there is no slop the sealed bearing idler is smooth and silent...it works good.

MotoMagz

Moto Mags. That looks good. Where did you get the brackets that go on the seat tube? Are they drilled out Happy Time mounts? Where did you get the gear wheel? Is that a TSC part for go carts, or did you add it? I like the neoprene roller a lot.

Does yours spring up on the chain? I think that is the best method, if you have enough force to not derail during pedal starting. If you spring up on the chain, then all the torque the motor can provide will not slacken the chain.

Happycheapskate,the mounts are from and old motorbike 2 stroke but not the happy time type.
The spring and arm are from the TSC tensioner.I drilled out the post that held the rubber roller. Then added the #41 chain idler wheel.You can get them of Ebay they also work well on the stock tensioner bracket
Yes it springs upward.

MotoMagz

Thanks for contributing to the thread. I wonder if the happytime type brackets can work in a similar fashion, since they are for 6mm screws, and I used a 6mm screw with a plastic bushing and it works well.

The Bikeberry Grubee kit came with an extra block type bracket and an extra couple of thin brackets for various down tubes.

I've been riding to work again and having a Happy Time again. It is the fun part of my day.