Couple questions about rear drive set up.

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biknut

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Sep 28, 2010
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I'm working on my second build. I volinteered to build it for my life long best friend. His bicycle is a OP Roller he bought at Wally World. He rides a ZX10R and isn't completely sold on motor bicycles, but I'm convinced he'll come around. I want to do the best I can for him.

I'm trying to upgrade everything I touch. Right now I have two questions.

1. The strap that holds the coaster brake arm looks really flemsy. Are better ones available, or should I just make one?



2. We've decided to use the stock rag joint with the stock sprocket. My question about this is, how perfect does the sprocket need to be? My feeling is it's going to be almost impossible to get it perfect. How close does it need to be? We're using it more for experience than saving money.
 
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2door

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Sep 15, 2008
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The closest you can get to "perfect" the better. Any side to side or up and down wobble can cause you problems in the way of the chain coming off.
Keep working on it. Spin the rear wheel and use a magic marker (Sharpie) to mark where the sprocket needs to be moved/tightened to get the best running. I try to shoot for as close to perfect as I can get it.
A rubber or plastic mallet or a hammer and a block of wood can be used to tap the sprocket into concentricity as far as getting it centered on the rear hub. If there is a side to side wobble, loosen/tighten the bolts to achieve the best alignment.
I've had some sprockets that were not flat and needed to be fixed. I've used a large crescent wrench to bend it so it runs true.
When tightening the nine bolts try to get them close to the same torque value. Use a cross pattern (one side then the opposite side) when tightening them. I use a cordless drill with an adjustable clutch and tighten them all the same increasing the torque with each revolution.

As for the coaster brake arm. The stock one will probably suffice but it isn't difficult to fabricate a new one from heavier material if you're concerned about it.
Tom
 

biknut

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Thanks 2door. I only started on the sprocket today. I was using a rubber hammer. The process seems really time consuming. Makes the sprocket adapter look like a great deal for $60 if time is money. I'm such a perfectionist I can see hours ahead just on this one thing.

I've got the up and down pretty close now but the back and forth is a long way to go.
 

corgi1

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Aug 13, 2009
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I've not seen(remember) the straps having all the weakening holes built in them,I personally would regrease the rear wheel now and try at H Depo or such for a solid looking strap,,,and an 1/8 of an inch out of round moves 1/4 of an inch from one side to the other,or forward and back "and forward"again 6 1/2 times a second at 30 mph,thats a lot of shaking of the chain and little bolts
xct2
 
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biknut

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Sep 28, 2010
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I worked on it a little more and without too much work the back and forth got better, but now I can see the up and down better and it needs more work which means a lot of loosening, and adjusting and tightening and loosening and adjusting and tightening and
 

joabthebugman

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Jun 21, 2010
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I have had two of those straps fail, both times it caused damage to other parts of the bike

Had it happen just tonight
Now I have to buy a new chain because the old one is twisted like a pretzel

It also throws your leg when you hit the brake, the first time so hard it almost knocked me off the bike
On top of that when it fails you have no brakes if you have not added auxiliaries, which thankfully all my bikes have
 

biknut

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Sep 28, 2010
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I have had two of those straps fail, both times it caused damage to other parts of the bike

Had it happen just tonight
Now I have to buy a new chain because the old one is twisted like a pretzel

It also throws your leg when you hit the brake, the first time so hard it almost knocked me off the bike
On top of that when it fails you have no brakes if you have not added auxiliaries, which thankfully all my bikes have
Thanks for the warning. I know what you mean.
 

biknut

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Sep 28, 2010
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I've not seen(remember) the straps having all the weakening holes built in them,I personally would regrease the rear wheel now and try at H Depo or such for a solid looking strap,,,and an 1/8 of an inch out of round moves 1/4 of an inch from one side to the other,or forward and back "and forward"again 6 1/2 times a second at 30 mph,thats a lot of shaking of the chain and little bolts
xct2
I did stuff some fresh grease in the bearings. I plan to tear it apart and redo the rear hub with fresh grease after about 50 miles.

I just paid REI $25 to true a cheap wally world, crooked from the factory rear wheel.
 

biknut

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Sep 28, 2010
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Damn, I've spent about 2 1/2 hrs, maybe more by now. It's pretty close, but I could probably spend another hour on it.

Now that I have "experience" what I've learned is if you use this POS#%t instead of buying a hub adapter in order just to save money you're a cheap assed mofo and I wish you were here right now so I could punch in the ever lovin mouth lol.
 

biknut

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Sep 28, 2010
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Alright I'm finally done with that. It took about 3 hrs over 5 days time. I decided to punch myself in the mouth a couple times for good measure.

On the plus side the sprocket looks lined up pretty good with the front sprocket. I have concerns that starting the bike will yank the sprocket out of true. If that happens one time it's toast for sure.

Thanks everyone for you help. Now on with the rest of the build.
 

joabthebugman

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Jun 21, 2010
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I have come to firmly believe that the rag joint not only has the potential and probability of warping spokes , but also severely reduces the life of the bearings by skewing the wheel to the left every time you start the motor and keeping it torques to the left while you are riding

I just can't afford the $80 or so dollars it would take to add the adapter to every build
 

corgi1

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Aug 13, 2009
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And you don't like the sproket that has the lock in pins and centers wihi the axle?
 

joabthebugman

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Jun 21, 2010
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And you don't like the sproket that has the lock in pins and centers wihi the axle?
Not really
I watched the installation video and it looks like variation of the rag joint with a disconnectable drive sprocket

it's the whole driving the spokes instead of the hub idea that I disagree with
 

corgi1

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it is a variation of the rag joint but with a lot more bolts holding it togeather,and it seems to involve more width on the spokes toward the hub.
The main thing I looked at was the main gear part was on a bearing and the mount in the center of the bearing centered beacause the axle went through the small hole the size of the axle in the center of that,the pins were just a noisey way to connect the drive.
We need some reviews from some people that bought it and are actually useing it.It does look easy ,my concern was the two pins ratteling