quick sprocket installation question...

nightcruiser · Jul 7, 2011

I am installing my first Grubee SkyHawk 2010 66cc engine kit and have found the instructions for installing the sprocket to be a bit vague. I want to get it right so I am hoping someone here will help me out a bit.

I have the standard sprocket, two rubber discs, a two piece round metal bracket, a three piece round metal bracket and nuts and bolts.

The sprocket fits my wheel perfectly, so I don't have problems in that area, but I am confused about the order of assembly of the parts.

First off, which side of the sprocket faces in toward the spokes? I am assuming the sprocket mounts so the offset moves the chain away from the spokes??

Next, I know one rubber disc goes on the inside of the spokes, but what about the other? Do I need a rubber disk on BOTH sides of the spokes? (one behind the sprocket and one on the other side of the spokes?)

Finally, I know one set of metal plates goes inside the hub, but what about the other?

The instructions are confusing, the illustration seems to show BOTH rubber disks and both sets of metal plates stacked up inside the spokes?

I know its not rocket science, but I am kinda lost as to what they are telling me to do here... Some instruction and/or pictures of a properly assembled sprocket would be helpul to me...

Thanks in advance for your input...

GearNut · Jul 7, 2011

http://motorbicycling.com/f3/rag-joint-28523.html#post270729
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The sprocket is dished to allow you to get the best chain alignment. You do not want the chain to run crooked. Dish side in or out depends on what you need for proper alignment.
You do not need to use both sets of metal plates. Use the set that best fits your installation.
Note, some folks use one set to help with alignment by placing them in between the sprocket and outer rubber rag joint. I am not saying to do this right now, it's just a little trick if you find yourself needing the sprocket moved out away from the wheel a little bit more.

The other set needs to go in between the lock washers/ nuts and the inner rag joint.

nightcruiser · Jul 7, 2011

GearNut said:
http://motorbicycling.com/f3/rag-joint-28523.html#post270729
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Thanks, that link was somewhat helpful. I know now the rubber rings are called "rags" and I should use one on both sides of the spokes...

Still I am wondering about the two sets of round metal brackets. Do I stack them on top of each other with the joints staggered on the inside of the hub? (after the rag) The instruction illustration seems to show this, but the picture right next to it seems to show one set of brackets between the outer rubber and the sprocket, and the other set on the inside?

Does anyone have a good picture of a properly assembled sprocket showing the order these parts are sandwiched together?

nightcruiser · Jul 7, 2011

GearNut said:
http://motorbicycling.com/f3/rag-joint-28523.html#post270729
_______________________________

The sprocket is dished to allow you to get the best chain alignment. You do not want the chain to run crooked. Dish side in or out depends on what you need for proper alignment.
You do not need to use both sets of metal plates. Use the set that best fits your installation.
Note, some folks use one set to help with alignment by placing them in between the sprocket and outer rubber rag joint. I am not saying to do this right now, it's just a little trick if you find yourself needing the sprocket moved out away from the wheel a little bit more.

The other set needs to go in between the lock washers/ nuts and the inner rag joint.

Thanks a bunch for clearing that up about the metal brackets and the sprocket dish. I think that pretty much answers all my questions... at least for now....

GearNut · Jul 7, 2011

The order goes as follows, viewed from the outside inwards:
sprocket, rubber, spokes, rubber, metal plate, lock washer, nut.

Edit: I keep editing my posts for clarity and more information and you read them and respond before I am done editing.

Sorry for any confusion...

MarkSumpter · Jul 7, 2011

GearNut is right that there is some latitude to mounting the sprocket for alignment but the proper order is dish side out away from the spokes then metal sheath, rag joint. spokes, rag joint, metal sheath then washers and nuts. The inner metal sheath is optional and used if you need to outset the sprocket more and the rags can be ground down in width if needed for alignment.

Another trick I have found useful is to use pieces of wire ties to shim up the sprocket where it is laterally true (NO FRONT TO BACK WOBBLE OF THE SPROCKET) before tightening the nuts, plates and rag joints to the spokes.

Personally I will never use another rag joint. Depending on what hub you have there are 2 really good adapters that remove the stress of the engine torque from the sprocket and the nightmare of alignment and hassle of all of those nuts.

My favorite is from Sports Car Pat. It is a 3 piece unit with recessed headed sprocket bolts so you dont have to bend on the brake arm for it to clear the bolts. The second is from Manic Mechanic. Both are available through most dealers but I know Robert at Piston Bikes has them in stock most of the time. They really do make life alot easier and the bikes run way better than with the rag joint.

nightcruiser · Jul 7, 2011

Thanks for all the input....
I have assembled the sprocket assembly several ways, it seems the closer to the spokes the better as far as chain alignment goes. I liked it best with no rubber between the sprocket and spokes cause chain alignment was best and sprocket was exactly centered because it's hole exactly matches the hub size.
That said, I understand it is improper not to use a rubber between the sprocket and spokes so I will put one in there and see how the chain flows. If it runs too wide I guess I will have to disassemble the rag joint and thin down the rag that goes behind the sprocket.
I guess I wont be needing the second set of metal brackets since I need less sprocket offset rather than more....
Thanks a bunch for all of your timely feedback....

nightcruiser · Jul 7, 2011

Hey guys, I'm not using this other hub so I think that is a discussion for another thread. Not to put you guys off, cause I really appreciate the input, but I have a rag joint here that I am struggling with...

I finally decided what order to put the pieces together and getting down to the last couple bolts I see they dont want to fit, some spokes are interfering. So I count the spokes, 16 per side, 32 total. DAMN. This is a pretty standard mountain bike wheel off a vintage '89 Specialized RockHopper Comp bike, I didn't expect this to be an issue...

The sprocket is made for a 36 spoke wheel, I have 32, what to do????

Any suggestions?

MarkSumpter · Jul 7, 2011

For my part I'm sorry for the thread being hijacked but it was.

All you can do is shim the sprocket laterally (front to back) the best you can and tighten it. Your kit came with 410 chain and in my experience if there is any runout at all you will get a lot of chain stretch and have to constantly adjust the tensioner. You might run 415 chain as it is a little heavier and much more forgiving to chain stretch.

paul · Jul 7, 2011

i cleaned up this thread. welcome nightcruiser and i hope you got the information you needed to get your motorized bicycle going,. here is a pictorial a friend of mine did on installing your sprocket with what came with your kit http://www.chrishill.myknet.org/Sprocket installation.htm

MarkSumpter · Jul 7, 2011

paul said:
i cleaned up this thread. welcome nightcruiser and i hope you got the information you needed to get your motorized bicycle going,. here is a pictorial a friend of mine did on installing your sprocket with what came with your kit Bicycle Engine Kit - Sprocket Installation

Thanks Paul...

nightcruiser · Jul 7, 2011

Thanks for the cleanup, I would prefer not to have the thread devolve into an argument about some other product I don't even have.....
Anyhow, my problem now is I have a 36 spoke rag joint sprocket and a 32 spoke wheel....
I pulled out the rubber "rags" for now so I can eyeball the alignment of the holes and spokes a bit better. It seems I can get 6 of 9 bolts through with the sprocket exactly centered. I can force a 7th through but its got slight interference with a spoke, the last two are a no go. With the 6 bolts in place and the sprocket dead center it looks like I could drill 2 holes in the sprocket (and all the other hardware) on center between the 3 holes where the bolts don't fit and they would fit through the spokes perfectly. This would leave me with 8 of 9 bolts in place, and spread those bolts evenly across the span where they don't want to fit.
Is this a bad idea? Heard of anyone doing this before?

nightcruiser · Jul 7, 2011

paul said:
i cleaned up this thread. welcome nightcruiser and i hope you got the information you needed to get your motorized bicycle going,. here is a pictorial a friend of mine did on installing your sprocket with what came with your kit Bicycle Engine Kit - Sprocket Installation

Thanks again, I just noticed the link to that most excellent write up about installing a rag joint sprocket.... Now I only wish I had a damn 36 spoke wheel!

MarkSumpter · Jul 7, 2011

Personally I havent tried to mount a rag on a 32 spoke wheel but it the bolts are reasonably spread out it should work OK. Give it a try and if need be I have a couple extra rag kits if you need them.

Again sorry for the stuff.

rohmell · Jul 8, 2011

32 spokes shouldn't be too bad...

I had to install one on a wheel with 28 spokes. I had to twist and turn, trick, fake, force, shove and cheat the thing onto the wheel, but I managed it, and rode that wheel for a year and a half before picking up a wheel with 36 spokes.

A 5 minute job became a 5 hour job with that wheel.

MarkSumpter · Jul 8, 2011

rohmell said:
32 spokes shouldn't be too bad...

A 5 minute job became a 5 hour job with that wheel.

You have me seriously spanked rohmell if you can do a rag in 5 minutes. Even after doing as many as I have they still take me at least a 6 pack before I can start one...

nightcruiser · Jul 8, 2011

rohmell said:
32 spokes shouldn't be too bad...

I had to install one on a wheel with 28 spokes. I had to twist and turn, trick, fake, force, shove and cheat the thing onto the wheel, but I managed it, and rode that wheel for a year and a half before picking up a wheel with 36 spokes.

A 5 minute job became a 5 hour job with that wheel.

I ended up drilling two extra holes in the sprocket and rag joint midway between the 3 holes that have interference with the spokes, wasnt as tough as I thought it would be. I used one of the bracket sections to mark out the holes, then bolted the bracket to the sprocket at drilled. Then I disassembled and reassembled with the rag joint in place and drilled the holes through the rags. Finally assembled the unit, bolts fit right in, there was a some wobble that I was able to work out with a little coaxing, I think its good to go now.
I was surprised this kit didnt fit right on my standard (late model) mountian bike rim, didn't expect that to be a problem, gotta figure lots of people have run across this problem before me? I didn't even count the spokes before I had trouble fitting the sprocket, I had just assumed it was standard and would fit. Right about now I am thinking its odd there wasn't a choice between a 36 spoke 9-bolt rag joint and a 32 spoke 8-bolt rag joint......
Next up, bending this damn muffler pipe a bit so it will clear the cranks, so far this seems tougher than I expected.....

Dan · Jul 8, 2011

The bending your muffler thing is an easy one as it happened to almost all of us at one time or another, snork. bending muffler - Google Search

My favorite is KC's method. He parked his truck on it, sat on the ground and pulled it! lolol

I am really impressed with your idea to drill your rag joint. Simple and worked. Thanks for sharing. Gonna help folks. Always a way. Some how, some way.

If your muffler is just barely tapping your cranks, some times you can get enough just by loosening the nuts and holding the muffler away and re-tightening. I have also kicked em, hit em with hammers and cursed at em. Ya really don't wanna do that though. LOL

Post lots of pics!

MarkSumpter · Jul 8, 2011

Dan said:
If your muffler is just barely tapping your cranks, some times you can get enough just by loosening the nuts and holding the muffler away and re-tightening. I have also kicked em, hit em with hammers and cursed at em. Ya really don't wanna do that though. LOL

Post lots of pics!

Dan you forgot to mention that is also a great way to learn how to drill out broken muffler studs... LOL

Dan · Jul 8, 2011

That is a good point Mark. I really gotta stop saying that publicly, lol. But man it worked great and was one of those "I kill you!" moments. (I really did feel better. Had been a bear of a build) Funny part, it was just enough!

I really should have mentioned the absolute easiest way I have found is putting the flange in a bench vise and just gently leaning in to it with your hip. Works great. But there are so many other ways folks have found, is easy to find one that will work with what ever tools you have on hand.

Am I the only one who thinks parking your truck on your muffler to bend the pipe is hysterical? Really, really cracks me up. http://motorbicycling.com/f3/truck-vice-tailpipe-bending-22197.html
Always a way

quick sprocket installation question...

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