For coaster braked bikes, my first kit (Grubee) said to leave off the outside rag washer. I've since started making a 1/32" Vellum gasket between spokes and sprocket plate with OD just below bolt holes. My outside rubber then gets cut through the bolt holes into a narrow circular shape and all sandwiched together. Opening up the sprocket center is a tedious grind and check fit affair. I don't disturb the dust cover and STILL have to rebend the brake control arm a little. WHEW! Does work however.
Sprocket Installation - Bicycle Engine Kit
- Thread starter paul
- Start date
If I sandwich the spokes, I don't have enough rom for my 36T sprocket, which does not have a concave side to it, to sit on the Axel/dustcover. If I tried it that way my sprocket would be literally resting in the air and it would move around too much to use.
Did you tighten the bolts hard enough...?
Nashville Kat
Well-Known Member
I have the sprocket on my Micargi cruiser with only one donut inside, BUT, there is a stop ridge on the hub which fits the sprocket hole perfectly otherwise (it's a 7 speed hub), and so the stop ridge keeps the sprocket 1/8" off the spokes- No Problems.
I had the original on shiney side before getting a 36 tooth- unlike the instructions said, which I think are rigid and opinionated. Maybe that's best for coaster brake. But somebody meant for the shiney side out and the offset teeth in. On this bike, that's what alligned best. The important thing is always the allignment- sight it carefully,
but, no, don't torque the bolts down so the sprocket pushes on bare spokes!
I have this other Schwinn Traveller build with the red 34 sprocket bolted directly to the Schwinn 10 speed hub-
I bored and drilled this sprocket myself, and it won't fit on another hub, and the standard kit sprocket would not fit on it without an adapter- the high flanges would be in the way. But Holy Cow, is it lightweight! Have a narrow 410 chain and sprocket on motor. The build is done but waiting for the weather to test. It unscrewed the new narrow motor sprocket the first time, while trying to pedal start, but think it's tight now.
I had the original on shiney side before getting a 36 tooth- unlike the instructions said, which I think are rigid and opinionated. Maybe that's best for coaster brake. But somebody meant for the shiney side out and the offset teeth in. On this bike, that's what alligned best. The important thing is always the allignment- sight it carefully,
but, no, don't torque the bolts down so the sprocket pushes on bare spokes!
I have this other Schwinn Traveller build with the red 34 sprocket bolted directly to the Schwinn 10 speed hub-
I bored and drilled this sprocket myself, and it won't fit on another hub, and the standard kit sprocket would not fit on it without an adapter- the high flanges would be in the way. But Holy Cow, is it lightweight! Have a narrow 410 chain and sprocket on motor. The build is done but waiting for the weather to test. It unscrewed the new narrow motor sprocket the first time, while trying to pedal start, but think it's tight now.
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nogoodnic
New Member
Let me re-itterate this point if you missed it earlier in the thread:
I purchaced my first bike about four years ago assembled. I rode it the first summer and noticed that I had a wowy in my rear wheel. After checking I found a couple of broken spokes. Ridding season was winding down so I continued to ride on it until winter. When snow started flying, I tore the wheel down and found seven broken spokesand the heads almost worn off of most of the spokes on the drive side. The moral of this story is to never mount metal to metal when it comes to spokes. With spring comming up I would reccomend everyone to go through everything on their bikes and making sure everything is tight and nothing is broke...Kelly
I also only use coaster brake wheels and have had no issues since this on any of my five bikes. Metal to metal is bad...Kelly
I installed the sprocket kit last night and it was a pain in the keister! I must have spent about 3 hrs working on it. The big issue I had was the bolt pattern just didn't line up with the spokes. There were always 2 "X's" of spokes that would hit the sprocket no matter how I twisted and turned it around. I finally was able to install 8 of the 9 bolts and after reviewing the situation for quite some time I decided to drill a new hole 1/4" further out towards the teeth from the original hole. I figured this would be fine and keep everything more balanced and secure. Good thing I put a graphic on my sprocket so the previous hole is not to noticeable. I'll put picts up later.
Brian the Sign Guy
Everett, WA
Brian the Sign Guy
Everett, WA
Hey guys, I installed my sprocket last night/ again today. So far it's being incredibly frustrating. Two of the bolts have snapped on me (upgraded to grade 8's now) and I can't get the thing centered if my life depended on it. I can get it initially but as soon as I tighten the bolts to where you can't move the sprocket the thing goes out of wack. Ive put it together and taken it apart at least 3 times now. How important is centering the sprocket? It has a pretty terrible wobble to it but I have no clue if thats normal for these bikes at all.
Mike,
Like I mentioned it took me a long time to get it right. What I ended up doing is snugging the bolts down in an alternating fashion like putting on a regular car tire. I would only snug them up a little bit at a time and when the rubber pads start touching or snugging to the spokes you can still adjust the sprocket a little (you may need to tap it lightly with a hammer) to maintain the centered. From there slowly tighten like you've been tightening until it's all tight and you are good to go.
If the sprocket is not centered it will pull hard on the chain then slack, pull hard then slack and really cause havoc with the entire drive and motor do to those stresses. Best of luck,
Like I mentioned it took me a long time to get it right. What I ended up doing is snugging the bolts down in an alternating fashion like putting on a regular car tire. I would only snug them up a little bit at a time and when the rubber pads start touching or snugging to the spokes you can still adjust the sprocket a little (you may need to tap it lightly with a hammer) to maintain the centered. From there slowly tighten like you've been tightening until it's all tight and you are good to go.
If the sprocket is not centered it will pull hard on the chain then slack, pull hard then slack and really cause havoc with the entire drive and motor do to those stresses. Best of luck,
psprat496
New Member
What I actually did with my first build was get a copper pipe that fits inside the center hole in the sprocket and I would just go around tightening the bolts. The pipe kept the sprocket completely centered and was the best you could ever get it. But I still ditched the old rag mounts and went with Manic Mechanics adapter. His ad is on the top left of this page. He really makes the adapter anyone could ever ask for.
That adapter looks awesome. I'll have to get out the rubber mallet and try again when I get back from class. If that doesn't work then I'll look into the adapter, which seems like a better thought out design. Is there any problem with it slipping on the hub? Does it have anything to grip or do you just crank it down?
Sorry to hear of your dilemna Mike. I'd check the flatness of your sprocket plate on a flat counter top and also, while not likely, your spoke flange could be bent. Turn your bike upside down and spin the wheel. If it wobbles could be the wheel or a bent axle. the slightest wobble in the center will be very noticeable on a 9" disc. MM adaptor is of course your best option. Good Luck, it WILL be worth the effort! Also, I think if you're snapping Grade 8 bolts you may be overtightening and pulling the wheel out of round.
I was snapping the stock aluminum bolts. I have since replaced all the sprocket hardware with grade 8 to avoid potential future issues. I just tried again but the sprocket falls out of line every time I tighten the rubber up onto the spokes, even after tapping it back into place with a rubber mallet. If I ordered that adapter, do I need to also buy one of his sprockets or can I still use the one from the kit?
Edit: I'm not sure that one of those adapters will work well with my Shimano Silent Clutch hub. It has an hourglass shape.
Edit: I'm not sure that one of those adapters will work well with my Shimano Silent Clutch hub. It has an hourglass shape.
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psprat496
New Member
Yes I'm pretty sure you do need to buy his sprocket too. But let me tell you how great it is. It took me about half and hour to hook it up and the end result was just great. A perfectley trued up sprocket with no drop out. It's great. I went with a 38t and am able to cruise at 30mph no problem at about half throttle. This is the best thing I ever bought (next to my SBP Pipe)
psprat496
New Member
I don't think so. I mean I don't know how curved your hub is but the best thing to do it to just call up Jim and ask him. I'm pretty sure the hub needs to be flat from end to end but like I said I don't know how curved your hub is.
MotorBicycleRacing
Well-Known Member
Nice pics, you did nothing wrong. You can
A] bend a couple of jogs into the brake arm so it clears the heads, easy if you have a vice
or
B] Countersink all 9 sprocket holes and use flat head allen machine screws,
probably easier to use 1/4 20 and get all new nuts and washers.
Mike B
New Member
I just did mine and I didn't use the the sprocket to spoke rubber. It wouldn't have worked, there was no way the brake arm would have fit. I did use the thinner (2 piece) steel rings between the sprocket and spokes to get more clearance and I am going to offset the engine an eighth of an inch too.
To even do this I had to reverse bend the brake arm and grind the sprocket bolt heads a little. Also had a machine shop cut the sprocket center hole to 1.53 to clear the dust cap.
But I did this on a custom wheel I ordered up. Steel with 12g steel spokes, Shimano coaster and 22 tooth sprocket. The 6 mm bolts just fit in the spoke cross area, I am glad I didn't order 11g spokes.
We shall see how it works.
To even do this I had to reverse bend the brake arm and grind the sprocket bolt heads a little. Also had a machine shop cut the sprocket center hole to 1.53 to clear the dust cap.
But I did this on a custom wheel I ordered up. Steel with 12g steel spokes, Shimano coaster and 22 tooth sprocket. The 6 mm bolts just fit in the spoke cross area, I am glad I didn't order 11g spokes.
We shall see how it works.
Leaving the rubber out is a mistake. Don't bolt the sprocket directly to the spokes. You'll end up bending them and causing them to loosen.
There's no reason you can't bend the brake arm enough to clear the bolt heads. Many have done it before you. A bench vise and a hammer or big Cresent wrench will work. It shortens the arm just a little but that will not effect the brakes.
Repeat: Don't run your bike with the sprocket bolted against the spokes.
I'm also curious how you "offset" the engine in the frame.
Tom
There's no reason you can't bend the brake arm enough to clear the bolt heads. Many have done it before you. A bench vise and a hammer or big Cresent wrench will work. It shortens the arm just a little but that will not effect the brakes.
Repeat: Don't run your bike with the sprocket bolted against the spokes.
I'm also curious how you "offset" the engine in the frame.
Tom
First of all you have to start with a wheel that is true. That means that the spokes are all adjusted properly. If you've been unsuccessful at getting the wobble out by adjusting the bolts then there is a good chance the sprocket is warped. In that case no amount of bolt tightening/loosening is going to help. Remove the sprocket and lay it on a flat surface (a sheet of glass is the best indicator) and check to see if it is flat. If it has a warp you can work it out with a plastic head hammer or a large Crescent wrench. Keep working until the sprocket lays flush against the glass.
There's also the chance that the rubber parts are not cut properly. I've seen them where one side is much thinner than the other. Check the rubbers and see if they are consistant thickness throughout their circumference.
Good luck.
Tom
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