Metal CNC chuck plate adapters for back power wheel?

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jeffpas

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Jan 2, 2023
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I finally got my bike assembled (I was called off the project on lots of other things) and now someone suddenly mentioned that they thought the biggest problem with these 2 stroke bicycles is the rag joint that comes with these kits going out of whack, which according to them is a hazard.
They then mentioned what they called a CNC plate adapter, saying they replaced the back wheel rag with this and it solved the problem. I had never heard of this until now.
I'm thinking its called a CNC hub mount. Of course that makes perfect sense to me as the rag joint is made from tire material and I could see that not holding the chain true with the back sprocket.

Does everybody agree this is an important upgrade? And if so and if you've tried it, what CNC plate adapter have you used. I found this video but it gives very little info as to where to find one, or how to find the right one to fit your bike :/


 

jeffpas

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Jan 2, 2023
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I'm now thinking its going to be a pain to find the right CNC plate to fit my bike, idk.
Some said it solved everything. But then this comment someone added on the very video adds to the debate:

"....Giving false information on a rag joint. When you first install a rag joint you make sure it is straight and true. Through the break-in period of the motor. Tighten up the bolts. Make it through again until that rag joint presses. After 3 of tightening it through your motor break-in. It becomes hard as a rock. Never had an issue with a rag joint. And never had an issue with bending Spokes and breaking them. And still spins perfectly true. I've heard many times of Hub adapters. Twisting on the Hub. And snapping spokes. And grinding into your hub. If you're going to use Hub adapters. Make sure that you properly install them. And still you will have issues with them. And be careful they will rip your spokes apart if not properly installed. And plus it's going to cost you more money. When the rag joint is just as good....."
 
Oct 11, 2023
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There are methods of truing the rag joint, and if you’re just running a basic 2 stroke with no performance enhancements, I think the rag joint is ok up to certain speeds. I ran them on a couple different kit builds, but I did have some issues with them. Quite honestly, I’m currently working on a non kit build that will go very fast and I’m not even messing with bicycle rims. I went to moped rims, the sprocket bolts directly to the hub, no adapter is needed, and I can use speed rated tires which I feel is very necessary at the speeds I plan to be going. Im not saying it’s what everyone should be doing, just that it’s the way I chose to go, and it avoids several problems. It avoids needing any kind of adapter and worrying about it possibly slipping, and it avoids worrying about my tires shredding at 40-50mph. The adapters can slip and break or bend spokes if not installed correctly.
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Los Angeles, CA.
The rag joints that are supplied in the kits can work very well if you take your time to install them correctly.

I've been doing it for years & I can get the sprockets almost perfect every time.

The hub adapters are a very good upgrade, but you need to be sure it will fit your hub! (luckily, 90% of the hubs out there measure the same.

The next thing to consider (if you're going with a new hub adapter) is what size sprocket to buy with it.... Many guys will get a smaller than stock sprocket to try to go faster (40T or 36T); If you have a lot of hills in your area, you should consider buying a 44t (stock size) sprocket.
 

jeffpas

Member
Jan 2, 2023
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I have a larger 48 tooth sprocket on mine. I wanted the larger sprocket because I wanted the torque, and I got the bike as a backup for commuting when my car is in the shop so I don't care about speed.
I spent a long time fussing with the rag, but I don't like the idea of it going out of whack and getting stranded miles from home. The hub seems a lot more solid.
But yeah, will it fit my bike? Which one to buy.
I've seen some around $20 bucks, it seems well worth it if it offers dependability. Though I just got it finished and I'll have to take the wheel apart again....

>>I think the rag joint is ok up to certain speeds>>
Here's where I'm curious. Project Farm tried assembling one of these from a kit and said that the bike was great up to a certain speed then started shaking more. I'm wondering if this is the rag joint vibration, and if the CNC hub would fix that?
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,250
1,767
113
Los Angeles, CA.
The rag joint is fine at high speeds as long as it's installed as perfectly as possible... & with a 48T sprocket; you won't be going that fast.

I've never heard about the rag joints going 'out of whack'... They're actually very reliable & will pretty much stay exactly as good as they're installed... Try not to over tighten the bolts because the rags can pinch & eventually break cheap thin spokes. (but you can also break spokes with a hub adapter if it isn't tightened enough).

Hub adapters are easy to install, a lot more accurate & look cooler.

95% of the vendors that sell them have left this forum... but you can find hub adapters all over the place if you look... Google 'motorized bicycle parts' to find more vendors, & eBay & Amazon are also good places to look.
 
Oct 11, 2023
56
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I have a larger 48 tooth sprocket on mine. I wanted the larger sprocket because I wanted the torque, and I got the bike as a backup for commuting when my car is in the shop so I don't care about speed.
I spent a long time fussing with the rag, but I don't like the idea of it going out of whack and getting stranded miles from home. The hub seems a lot more solid.
But yeah, will it fit my bike? Which one to buy.
I've seen some around $20 bucks, it seems well worth it if it offers dependability. Though I just got it finished and I'll have to take the wheel apart again....

>>I think the rag joint is ok up to certain speeds>>
Here's where I'm curious. Project Farm tried assembling one of these from a kit and said that the bike was great up to a certain speed then started shaking more. I'm wondering if this is the rag joint vibration, and if the CNC hub would fix that?
I never ran a rag joint at high speeds. In fact, I’m currently working on my first high speed build. I went to moped rims mainly for the ability to run speed rated tires, they just happen to have the advantage of also having the sprocket bolt directly to the wheel. Venice Motor Bikes is an experienced builder, he’s been doing this at least a decade, maybe two or three I’m not sure, but if he says the rag joint is fine, I trust his experience. I’m only stating my opinion based on limited knowledge and experience. The bike will shake at a certain speed most likely due to the front fork not being stable enough (happens on motorcycles as well) or possibly one of both of the wheels not being true, or tires not balanced properly for the speed you’re going. At least those are the causes I know of. I only say the rag joint is ok for certain speeds because I don’t know what speeds they can handle, but I know they’re definitely fine for the speeds stock kit engines are capable of, and that’s more what I meant.
 
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Oct 11, 2023
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I’m just working on a 212cc build that will be geared for a top speed of around 65. Now I don’t plan on going that fast, but I didn’t want my cruising speed to be in the top of my rpm range as it’s harder on the engine and there’s no more available power if needed. I’m a firm believer that extra power is a safety feature when used correctly. I’ll be cruising around 40-50mph mainly, as the speed limit between my house and my job (10 minutes, one road) is between 35-45mph and I like to cruise at around 5mph over the limit. So I feel safer running tires that are speed rated. Bicycle tires are not speed or load rated. Most can handle at least 30mph consistently if they are decent quality, but the tires I’m going to be running are rated for 81mph and 319 lbs. there’s no such thing as building an MB too safely.
 
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Tom from Rubicon

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Apr 4, 2016
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In March of 2016, my first build was a Huffy BBR 49cc Hua Sheng.
Rag joint was the sprocket mount method Dejour. The 31t sprocket I used has a internal opening to clear the hub dust cover. I made a disk snugly fitting the axel OD and the sprocket ID to ensure concentricity. By carefully drawing in the rag joint bolts, wobble has been kept to .020" indicator runner out. As per Norm "VMB" a properly built rag joint is a dependable assembly. CNC sprocket / hub mounts cost more. But for non mechanical people, they are useful.
Would I do another rag joint sprocket mount? No. But i could.

Tom
 
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jeffpas

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Jan 2, 2023
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The rag joint is fine at high speeds as long as it's installed as perfectly as possible... & with a 48T sprocket; you won't be going that fast.

I've never heard about the rag joints going 'out of whack'... They're actually very reliable & will pretty much stay exactly as good as they're installed... Try not to over tighten the bolts because the rags can pinch & eventually break cheap thin spokes. (but you can also break spokes with a hub adapter if it isn't tightened enough).

Hub adapters are easy to install, a lot more accurate & look cooler.

95% of the vendors that sell them have left this forum... but you can find hub adapters all over the place if you look... Google 'motorized bicycle parts' to find more vendors, & eBay & Amazon are also good places to look.
 

Tom from Rubicon

Well-Known Member
Apr 4, 2016
2,758
5,944
113
72
Rubicon, Wisconsin
I’m just working on a 212cc build that will be geared for a top speed of around 65. Now I don’t plan on going that fast, but I didn’t want my cruising speed to be in the top of my rpm range as it’s harder on the engine and there’s no more available power if needed. I’m a firm believer that extra power is a safety feature when used correctly. I’ll be cruising around 40-50mph mainly, as the speed limit between my house and my job (10 minutes, one road) is between 35-45mph and I like to cruise at around 5mph over the limit. So I feel safer running tires that are speed rated. Bicycle tires are not speed or load rated. Most can handle at least 30mph consistently if they are decent quality, but the tires I’m going to be running are rated for 81mph and 319 lbs. there’s no such thing as building an MB too safely.
Would you be so kind Bruce, to post some photos of your 212cc build? Or some concept designs.
It sounds like you are building a daily driver / commuter.

Tom
 
Oct 11, 2023
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Would you be so kind Bruce, to post some photos of your 212cc build? Or some concept designs.
It sounds like you are building a daily driver / commuter.

Tom
I don’t have any concept designs. I have a picture in my head and I’m figuring out how to make that picture a reality as I go. The bike isn’t done yet. Yes, the idea that a to build a bike I actually get to ride way more than I have to work on it. Hoping for once seasonal maintenance. Other than oil changes and minor adjustments. I’m basically building a motorcycle on a bicycle frame. It’s not even going to have pedals when it’s done. Automatic transmission so no need for pedals anyway.
 

jeffpas

Member
Jan 2, 2023
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I'm having the hardest time tuning the rag to be 'true'. I have it so it can crank spin with the bike upside down and not come off, but the sprocket teeth are only in the center of the chain in a few spots.
I've tightened down the other side so much I'm afraid the bolts will strip or pop.
Its seems its impossible to get it completely straight. IDK
One would think you could fiddle with the bolts and get it straight all the way around, as there are plenty of them but I just can't seem to do that.
If we can just get a day without rain, I guess I'll just try it out and see what happens.
 
Oct 11, 2023
56
47
18
I'm having the hardest time tuning the rag to be 'true'. I have it so it can crank spin with the bike upside down and not come off, but the sprocket teeth are only in the center of the chain in a few spots.
I've tightened down the other side so much I'm afraid the bolts will strip or pop.
Its seems its impossible to get it completely straight. IDK
One would think you could fiddle with the bolts and get it straight all the way around, as there are plenty of them but I just can't seem to do that.
If we can just get a day without rain, I guess I'll just try it out and see what happens.
From my understanding, you don’t want to just tighten the bolts as far as you can go. If you can see the splits in the lock washers, once the lock washers are completely flat is tight enough. From there, find something that can touch the edge of the sprocket maybe just below the teeth as it spins. Loosen the bolts that are parallel to any low spots, and tighten the ones parallel to any high spots. I believe that is the best method for truing, I’ve never done it, when I had the rag joints I never trued them and never noticed any problems with them, but truing them is not a bad idea at all.