Motorized Bicycle Engine Kit Forum  

Sponsors



Go Back   Motorized Bicycle Engine Kit Forum > Motorized Bicycle Mechanical Components > Hubs, Gearboxes, Sprockets and Chains

Hubs, Gearboxes, Sprockets and Chains Can't find 'em, grind em - hubs and transmissions, problems and modifications to make you run smooth and trouble free

Reply
 
Thread Tools Display Modes
  #1  
Old 05-06-2011, 08:16 PM
gobigkahuna gobigkahuna is offline
Motorized Bicycle Elite Member
 
Join Date: Apr 2011
Location: E NC
Posts: 268
Default DIY alternatives to the sprocket rag joint?

I'm looking to convert a bike with 48 spoke wheels so the standard 9 bolt rag joint won't work. the hubs are coaster brake styled, but I plan on disabling the coaster brake and using caliper brakes instead. Any DIY solutions that mechanically connect the sprocket to the hub without buy an expensive adapter or new hub?
Reply With Quote
  #2  
Old 05-06-2011, 09:04 PM
Mac's Avatar
Mac Mac is offline
Motorized Bicycle Elite Member
 
Join Date: Dec 2009
Location: Maine
Posts: 489
Default Re: DIY alternatives to the sprocket rag joint?

Check with Sportscarpet, he makes adapter with a 3.75 centerline, I have the same bike as you, I made a template out of paper, 3 point on that same circle, 120 deg apart, the hub on the Oynx is 1.519",within .004 of a CB110 hub, with my initial measurements and template, looks like his will work. I didn't order it yet($$) but a 50tooth sprocket will make up for the extra rollout of the 29" tire,{same as a 44with a 2 stroke} (if you have the 5:1 hoot gearbox),If you have a different gearbox, like a 3:1,let me know, I'll let you know the right sprocket size to keep the motor in the right RPM range. Mine has the 5:1gearbox and a 10to 44T final and its too tall, over 50 on a long downhill, bout 22 on level ground
Reply With Quote
  #3  
Old 05-08-2011, 05:23 AM
gobigkahuna gobigkahuna is offline
Motorized Bicycle Elite Member
 
Join Date: Apr 2011
Location: E NC
Posts: 268
Default Re: DIY alternatives to the sprocket rag joint?

Quote:
Originally Posted by Mac View Post
Check with Sportscarpet, he makes adapter with a 3.75 centerline, I have the same bike as you, I made a template out of paper, 3 point on that same circle, 120 deg apart, the hub on the Oynx is 1.519",within .004 of a CB110 hub, with my initial measurements and template, looks like his will work. I didn't order it yet($$) but a 50tooth sprocket will make up for the extra rollout of the 29" tire,{same as a 44with a 2 stroke} (if you have the 5:1 hoot gearbox),If you have a different gearbox, like a 3:1,let me know, I'll let you know the right sprocket size to keep the motor in the right RPM range. Mine has the 5:1gearbox and a 10to 44T final and its too tall, over 50 on a long downhill, bout 22 on level ground
I just checked at McMaster Carr and they carry shim material in .001 / .002 / .003" thickness, so that might be one solution. I'm waiting to hear back from Sportscarpat, but I'm hoping this might work.

Another solution, albeit a lot more work, is shown here: Rear Hub Sprocket Mount - MotoredBikes.com: Motorized Bicycle Forum (My appologies for the cross link to a different forum, but it's relevant to my question.)
Reply With Quote
  #4  
Old 01-07-2017, 08:50 AM
docimastic docimastic is offline
Motorized Bicycle Newbie
 
Join Date: Nov 2016
Location: Florida
Posts: 3
Default SOLVED: mount 9 hole sprocket rag joint on 48 spoke wheel

I KNOW this is an old thread, so please don't yell at me for adding to it. Maybe I should have made a new post?
Just built a Genesis GX7 ("29er" 48 spoke wheels) motorized bicycle using the rag joint with 9 hole sprocket. The trick is to use only 6 of the holes. Two bolts in adjacent holes, skip a hole, two more, skip a hole, and then two more. Lay the wheel flat and try a few different positions. It CAN be positioned so the bolts drop right through the spaces between the spokes with the sprocket perfectly centered.
One other thing... the "1/3 moon" plates will bend, unless a second set is added. I happened to have on hand both the "1/3" plates and the older style "1/2 moon" - 4 holes in one plate, 5 in the other - and used those in conjunction with the 3 hole plates. Not having tried it, but it seems that it should be fine if all the 3 hole type... if the second set is staggered in relation to the first.
Hope this helps someone!
Reply With Quote
  #5  
Old 05-07-2011, 04:22 AM
gobigkahuna gobigkahuna is offline
Motorized Bicycle Elite Member
 
Join Date: Apr 2011
Location: E NC
Posts: 268
Default Re: DIY alternatives to the sprocket rag joint?

@Mac - Do you have a link to Sportscarpet handy? I googled it and couldn't find it.

Edit: Never mind, found it here: http://motorbicycling.com/f23/sprock...pat-26938.html The only price I've found was $80 for the CB110 with a 40t sprocket. I wonder what it would cost for our hub + a 56t sprocket (I'm more interested in hill climbing power than speed).

So you're sure the 120degree mount spacing will clear the spokes? What about chain clearance? I've read that can be an issue with these. I plan on removing the coaster brake on mine and adding front and rear calipers.

The other direction I was thinking about was a diy jackshaft. I haven't seen too many attempts at it, but am only just starting my homework on the topic.

Last edited by gobigkahuna; 05-07-2011 at 05:39 AM.
Reply With Quote
  #6  
Old 05-08-2011, 12:02 AM
DuctTapedGoat's Avatar
DuctTapedGoat DuctTapedGoat is offline
Motorized Bicycle Elite Member
 
Join Date: Dec 2010
Location: Nampa Idaho
Posts: 1,171
Default Re: DIY alternatives to the sprocket rag joint?

Pirate cycles sells the clamshell adapters. HybriPed might work too. Myself, I've been on disc hubs, mounting the sprocket to the rotor mount, and I love it.
Reply With Quote
  #7  
Old 05-08-2011, 02:54 AM
gobigkahuna gobigkahuna is offline
Motorized Bicycle Elite Member
 
Join Date: Apr 2011
Location: E NC
Posts: 268
Default Re: DIY alternatives to the sprocket rag joint?

The min inside diameter for the Sportscarpat / Pirate cycles adapter is 1.522" while the hub diameter is 1.519", that's a 0.003" difference which isn't much but enough to keep it from working I'm guessing. I suppose a shim could be used, but it would have to be -real- thin, eh? I've sent an email to Sportcarpat but haven't received a reply yet. Failing that my alternatives look like they will be to either force the rag joint to work or get / build a jackshaft.
Reply With Quote
  #8  
Old 05-08-2011, 03:02 AM
DuctTapedGoat's Avatar
DuctTapedGoat DuctTapedGoat is offline
Motorized Bicycle Elite Member
 
Join Date: Dec 2010
Location: Nampa Idaho
Posts: 1,171
Default Re: DIY alternatives to the sprocket rag joint?

Well, you can always recut a larger circular hole in the center of the sprocket.
Reply With Quote
  #9  
Old 05-08-2011, 03:34 AM
gobigkahuna gobigkahuna is offline
Motorized Bicycle Elite Member
 
Join Date: Apr 2011
Location: E NC
Posts: 268
Default Re: DIY alternatives to the sprocket rag joint?

Quote:
Originally Posted by DuctTapedGoat View Post
Well, you can always recut a larger circular hole in the center of the sprocket.
Not sure how that would help. The sprocket adapter mounts to the body of the hub. My hub is 0.003" smaller than the sprocket adapter is designed for, so the adapter would likely slip. How would enlarging the center hole of the sprocket help?

I did look at the HybriPed site and I'm pretty sure that won't work, the holes for the mount looks like it's specifically designed for a 36 spoke wheel. It did give me an idea though, if I can locate a 50-56 tooth sprocket without the 9 bolt hole pattern, then I can drill my own holes. I'd have to make my own backing plate (do-able) and rubber rag backing (not sure if that's do-able) though. The other thing I noticed about the HybriPed is that it uses a lot more bolts to secure the joint. Looks considerably more secure than the standard 9 bolt pattern.
Reply With Quote
  #10  
Old 05-08-2011, 03:42 AM
DuctTapedGoat's Avatar
DuctTapedGoat DuctTapedGoat is offline
Motorized Bicycle Elite Member
 
Join Date: Dec 2010
Location: Nampa Idaho
Posts: 1,171
Default Re: DIY alternatives to the sprocket rag joint?

Oh, sorry. I was thinking you couldn't fit the hole over the flange.

For true DIY you could drill through the flange and sprocket, tap it and bolt your sprocket to the hub.

Though - you really don't need the plates from the rag joint. You could easily drill out a different hole pattern and make your own custom rag to fit, using washers to replace the plates.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 01:13 PM.


Sponsors

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
MotorBicycling.com