I realize there are several threads on this subject already but I thought if I share a little of my hindsight, it may help out an inexperienced builder or two. I would invite any with additional or different experiences to contribute them.
This is a motorized bicycle building forum and the source for many ideas and build plans, as it was for me. Accordingly many components will derived from bicycles. But for anyone planning to go faster than 30 mph and/or with an engine larger than the legal motorized bicycle limitation (i.e., 49cc), you might want to put some serious thought into wheels and tires before you begin your project. There are two or three reasons that this is important. Obviously, you want to be sure that the wheel components you select are robust enough to handle the additional stresses you will be putting on them related to the speed and weight. You also want to be able to brake effectively. Moped or Worksman/Husky drum hubs with heavy duty spokes and rims seem up to the task but are they really? It’s easy enough to decelerate for a stop sign but what about a panic stop from 40+ mph or more?
The other major component of the wheel assembly is the tire. While there are numerous retro bicycle tire options for 26 inch bicycle wheels, I have found only two tire options intended for motorized use: Coker and Continental KKS (The latter is a moped tire rated for 30 mph). They are actually 22” motorcycle tires. The Cokers are extremely expensive, maybe out of reach for the casual replica builder, and the KKS’s are hard to come by.
Another consideration is state safety inspection. If you plan to register your bike as a motorcycle, safety inspections are inevitable in most states. I’m sure the level of scrutiny varies from state to state and site to site but a standard item on their checklist is likely to be DOT rating for many components, including tires. I’ve heard in MD one can fail for turn signal lenses that don’t have “DOT” on them. Coker tires have a DOT rating but the KKS tires have the “European equivalent” which may or may not pass.
With all of these considerations in mind, I believe the next step for me will be 21 inch motorcycle rims and tires. “21” sounds really small but the outer tire diameter is actually very close to that of 26” bike tires. Narrow 21 inch drum-brake wheels were common on dirt bikes from the 70’s and 80’s. Serviceable front wheel assemblies can be found on ebay for less than a new heavy duty bicycle wheel. I much prefer the look ones with symmetrical spoke anchors. I’ll be getting a little further away from the vintage look I was shooting for but in the interest of safety and legality I think I can deal with it.
The narrowest motorcycle tire available (size 2.75-21 or 70/100-21) is a bit wider than the balloon style cruiser tires commonly used so clearance may be an issue. Oh well, I had in mind to build my own springer fork over the winter.
This is a motorized bicycle building forum and the source for many ideas and build plans, as it was for me. Accordingly many components will derived from bicycles. But for anyone planning to go faster than 30 mph and/or with an engine larger than the legal motorized bicycle limitation (i.e., 49cc), you might want to put some serious thought into wheels and tires before you begin your project. There are two or three reasons that this is important. Obviously, you want to be sure that the wheel components you select are robust enough to handle the additional stresses you will be putting on them related to the speed and weight. You also want to be able to brake effectively. Moped or Worksman/Husky drum hubs with heavy duty spokes and rims seem up to the task but are they really? It’s easy enough to decelerate for a stop sign but what about a panic stop from 40+ mph or more?
The other major component of the wheel assembly is the tire. While there are numerous retro bicycle tire options for 26 inch bicycle wheels, I have found only two tire options intended for motorized use: Coker and Continental KKS (The latter is a moped tire rated for 30 mph). They are actually 22” motorcycle tires. The Cokers are extremely expensive, maybe out of reach for the casual replica builder, and the KKS’s are hard to come by.
Another consideration is state safety inspection. If you plan to register your bike as a motorcycle, safety inspections are inevitable in most states. I’m sure the level of scrutiny varies from state to state and site to site but a standard item on their checklist is likely to be DOT rating for many components, including tires. I’ve heard in MD one can fail for turn signal lenses that don’t have “DOT” on them. Coker tires have a DOT rating but the KKS tires have the “European equivalent” which may or may not pass.
With all of these considerations in mind, I believe the next step for me will be 21 inch motorcycle rims and tires. “21” sounds really small but the outer tire diameter is actually very close to that of 26” bike tires. Narrow 21 inch drum-brake wheels were common on dirt bikes from the 70’s and 80’s. Serviceable front wheel assemblies can be found on ebay for less than a new heavy duty bicycle wheel. I much prefer the look ones with symmetrical spoke anchors. I’ll be getting a little further away from the vintage look I was shooting for but in the interest of safety and legality I think I can deal with it.
The narrowest motorcycle tire available (size 2.75-21 or 70/100-21) is a bit wider than the balloon style cruiser tires commonly used so clearance may be an issue. Oh well, I had in mind to build my own springer fork over the winter.
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