Back to basics.

[wrenchin 4 fun]

I got that sick yucky feeling when my KCM chain detonated during my ride yesterday. Lucky for me, I was only a mile from home and the bike would still roll with the chain lodged around the hub. The disaster forced me down the proverbial reliability rabbit hole, and after a lot of thinking while I walked the derelict home, I realized how far I had strayed from the main attraction of motorized bikes-simplistic fun. My first two builds were plain and practically bulletproof. Sure, I had to tinker on them now and then, but most of my time was spent riding. Ah, the good ole days. Then I started reading about all of the interesting things you guys were doing and I said, "wonder if I can do that." Before long, my bike was as complicated as an IRS 1040 long form.

Lights and a horn are practical, but do you really need them on a MB if you don't ride at night? Probably not. I rode an Allstate scooter without working lights for 2 years in junior high. And using a geared hub for a transmission seemed like a cool idea, but it added an extra chain not to mention the complicated design and alignment required to mount it mid-frame. Just because someone tries something cool doesn't mean it's a good idea. Another mistake was opting for vintage components because they look good. Drum brake hubs give a bike a 50-ish vibe, but they're heavy and maintenance on disc brakes is so much simpler. For a while I even had a fully outfitted tool box mounted behind my seat. I removed it a couple of weeks ago to save weight and make it easier to mount and dismount. In retrospect, my timing was lousy.

Long story, short, I'm slowly learning my lesson. The vintage hubs laced to vintage wheels with 10 gauge spokes are being swapped out for modern Rhino Lite rims with Avid disc calipers and stainless spokes from the parts bin. The Shimano Nexus hub has been moved from mid-frame to the rear wheel where it belongs. It's 48 tooth sprocket driven from the jackshaft by a 9 tooth sprocket should give me plenty of low end in first gear. Am looking for other ways to simplify like replacing the battery with a simple capacitor to even out the rectified current for my LEDs.

I remember stripping down my Honda Scrambler and Harley Sprint in High School. Guess history does repeat itself.

 

[Sidewinder Jerry]

Lights and a horn are practical, but do you really need them on a MB if you don't ride at night?

Well I can honestly say on several occasions my loud horn has caused cages to hesitate just long enough to realize I was going faster than they thought I was. Which caused them not to pull out in front of me. I seldom ride at night. Unfortunately many drivers today don't know what hand signals mean. This is why I have brake and signal lights. Mirrors are also a big help.

As on many threads I've tried explaining especially with the small 4 stroke engines there's a certain gear ratio width range you must stay within for the engine to function efficiently. The most common mistake is that range is too high. It's doing to the engine the same thing a cyclist would experience starting in the higher gears instead of the lower gears.


The reduction range on my bike is 66.79\1~16.25\1

 

[Gordy]

Another good inspiration is race bikes. Not just motorized bike race bikes, but race bikes through the decades. They're very straight forward, simple, and easy to access the important components.

 

[wrenchin 4 fun]

I'm amazed at the Harley race bikes restored by Wheels Through Time. Their riders were geniuses at cutting weight and keeping things simple for ease of maintenance. They would fix stuff on the fly and jump right back on the track.

 

[Gordy]

I'm amazed at the Harley race bikes restored by Wheels Through Time. Their riders were geniuses at cutting weight and keeping things simple for ease of maintenance. They would fix stuff on the fly and jump right back on the track.

It's a dream of mine to make a week trip out there. I'm gonna try and have enough saved up by my birthday to make a trip. It's not too far and I can sleep in my car comfortably. Just gas and food is a little spendy. I wanna make a week trip out of it so I can see everything in that museum

 

[wrenchin 4 fun]

Careful, Gordy, once you get in there, you'll never want to leave!

 

[Gordy]

Careful, Gordy, once you get in there, you'll never want to leave!

That's why we're making a week trip

 

[wrenchin 4 fun]

So far I've eliminated 2 sprockets, one chain, several brackets, and a bit of vulnerability. Next is a hard look at the SBP jackshaft that could be beefed up. Onward and upward.

 

[cloakedvillain]

You had that tandem, what about shortening it while retaining a relatively long wheel base? That gives you room for pedaling and integrating a jackshaft into the frame.

 

[wrenchin 4 fun]

That's a thought, CV, but I currently have my hands full redoing the J.C. Higgins build.

Rebuilding the rear wheel took an entire day. Below are shots of the caliper bracket for the 203mm disc brake and the 48-tooth sprocket. The bracket is a little odd because I used scrap flat steel to make it and it was already cut, so I had to jigger the design. Hooked up an Avid fully adjustable caliper then swapped the 36-spokie matching rim for a Rhino Lite double walled rim to match the 32 spoke Shimno Nexus hub. Had to swap the vintage 10 gauge Schwinn tandem spokes for 12 gauge stainless steel ones because the Rhino rim is drilled and gusseted for smaller nipples. I'm amazed that this Frankenstein configuration worked on the old Higgins frame, but it actually came out better than the drum-brake-hubbed wheel.

After the wheel was built and mounted, the real fun started! The chain would not clear the frame due to the enormous spread of the chain caused by this Mongo-sprocket. I tried every position for my jackshaft housing from just under the seat to just above the lower unit, no dice. After wasting a couple of hours trying different options, I concluded that the original path for a bicycle chain is the best option.

Now I have come full circle regarding the design of my drive train. I pulled out the SBP shift kit sprockets I used on my first build which was destroyed by a hurricane10 years ago. That first foray into motorized bikes was a built-up Murray Santa Cruz called the Red Hornet shown below. My moniker back then was Scootmeister, so nobody associates me with that build anymore, but you will recognize that several parts salvaged from that build now resides on the Higgins: the seat, the Rhino Lite rim, and the shift kit sprockets. I rode the wheels off of that bike including nearly every parade in the county and it never broke down. Sure wish I had that Phantom pipe back, but brackish is murder on all things metal.

By looking at that old build, I'm thinking the Higgins might be geared way too low. Here's what it looks like after countless hours and tons of materials wasted on amateur engineering.