Hub Issue

The Worksman wheels are great - and the best option for such a project. The rims are actually pretty accurate to the time - rolled from 1/8" steel. The spokes are .120. The front hub is steel while the rear hub is alloy with a 4" drum brake and is threaded for a freewheel. It actually stopped the bike admirably. My first experience/test ride revealed that the brake was almost ineffective. Perhaps the shoes have partially bedded-in or perhaps my adjustments to the linkage improved the leverage but they (it) sure work better now. I did find myself dragging my feet a few times trying to attenuate my speed through the crowd at the show. The foot pedal is not in the most convenient place and people just weren't moving enough. Even so, at walking speed I could easily keep the bike upright with both feet up. Maybe all the road cycling I do helps with that but I was happy the frame performed with some stability. Well, as mentioned, the alloy hub was designed for a freewheel. I covered earlier how I modified the supplied HD freewheel to hold a sprocket. I did not modify how it was mounted to the hub - via the traditional threads. These didn't last under the torque of the 13 HP engine. I did gag it a few times when the crowd would split and enjoyed the feeling of thrust. To me I thought that made the bike look like it really could do more than just putt through a fairground - like it really wanted to go...... and it did. The final moment was after leaving the show and riding around an adjacent block. About a block from the truck, and away from most of the crowd, I lost power. Looking down, I could see the PTO working. A guy walked up and told me the sprocket was "slipping". We ended up having a good conversation about the need for us to go to Davenport next year. He also noticed my, and I quote, "high dollar seat." He was correct on both accounts. Well, my correction to the problem is not completely solved. I really would like a cush drive of sorts but I'm not sure how to do it with this hub. I think I will simply build a spacer that will mount solidly to the hub and then to the existing bolt pattern of the sprocket. With this setup, I realize that any future failure of the sprocket mount could be catastrophic. There will be no threads to give way, no free-spinning parts. The body of the hub would fail around the axle bearing, drop the wheel to the side, and send the sprocket into the spokes. Either of these last two events would lock up the rear in a quick way. In the nature of the original risk-takers, I will use this anyway, and hope that it helps me "keep my foot out of it." For those contemplating this type of project, cush drives are a huge deal and were designed and used from the beginning - as in the 1910s. It's not something to blow off saying, "Well it's not like I going to race it or anything." I hear these kinds of statements all the time and they are typically to justify either a lack of money, a lack of detail, or a lack of ingenuity. That said, I have isolated my rear sprocket/wheel from much of the vibration problem by using the belt driven sheave on the jackshaft. The primary reduction is elastic, so to speak. The secondary is chain driven and prone to more shock. The engine pulsations are what does a lot of the damage and can otherwise transmit themselves all the way to the contact patch between the ground and the tire. An all chain-driven application is at a higher risk of failure without some form of cush drive. This was one of the major advantages of the older leather belt-driven machines. This pic shows the webs cast in the hub. I must avoid those when laying out a bolt pattern. A friend managed to get six bolts, two between each web, into his identical hub. I am going with three. First I used a 5/8" end mill to take down some of the casting so that the bolt heads would be on a flat surface. My friend bolted from the outside, threaded his hub, and added nuts inside. I feel a solid bolt shoulder would be best in my case - no more stress risers than absolutely necessary. I then drilled a 1/8" hole and flipped the wheel. Using a degree chuck(super spacer, whatever), I spaced two more identical holes (120 degrees apart) for a three bolt pattern perfectly spaced. One could also mount the hub on it's axle and affix a degree wheel(made from a printout available on the web) onto the hub and, using a fixed pointer, rotate the wheel the required amount and mark/drill or mark directly at 120 degree points at equal distances from the axle. How far out? Well, that's why I first flipped the wheel to identify the hub ribs and drilled the first hole from that side. One could even mount the wheel on the bike and scribe a line around the hub for the nominal bolt pattern line. Intersect the line with the degree wheel marks and there is your bolt pattern. You don't have to have many machine tools to do a job right. What you need is the patience to do it right. The layout is all the same, the tools just make the holes. If you do such things, take the extra time to center punch any marks for drilling, start with a small bit, and really clamp down the work - not just for safety but for much increased accuracy and neatness. A hole is not just a hole! Well, that's all for now. I have to build the spacer and mate that to the sprocket - maybe next week.