Give it a rest, soldier. Give it a rest.
Anyway, back to the same ol' grind. I have settled for the kind of motorization I want for my bicycle. It involves taking an engine and mounting it along with a jack-shaft onto the frame. I went as far as calculating the gear ratios I would need in order to achieve the top speeds, climbing speeds, and cruising speeds that I think are good for the bike. Using this gear ration calculator...
Keep in mind, the Stumpjumper I bought (btw a real gem! of a used bicycle :-P) has a rear 5-speed freewheel with a gear range 30-14. The highest being 14 tooth, and the lowest 30 respectively.
I wanted to swap out the rear hub for a more up-to-date 5-speed internally-geared hub, but all of them are for more recent mtbs so they have a hub spacing of about 135mm. My Stumpjumper (her name is Willow), so Willow has only a 120mm rear hub spacing. Which would mean I'd have to "cold-bend" the frame, which is possible given the chromolly steel construction of the frame, but not desirable.
After some searching around for the right gears and whatnot, I thought well I can just play with the gear ratios that are already available to me; taking the tiny liberty of buying the right sprockets when I buy the shift kit from SBP t-10 hours from now, I can really make the bike fly. I am brimming with anticipation!
So, a top speed of 41 mph sounds nice going 6500 rpm, which is where the engine redlines. The ratio of the gear box plus the jack-shaft freewheel sprocket is 5:1 * 17:10 and comes out to be 8.67:1.
I would then take the ratio of the drive/driven sprocket of the jack-shaft output sprocket to the chain-ring on the shift-kit crankarm assembly. This ratio is 4.36:1.
The final ratio is gotten by taking the ratios of the drive/driven sprocket of the bicycle's original drive train and the new 44-tooth chainring of the shift kit. It turns out to be 0.32:1.
All-in-all, I'd have a drive ratio of 12.04:1.
Using the largest cog on the rear multi-cog freewheel, I would have a drive ratio of 25.8:1.
When I want to go fast without revving the engine so much, I can simply go 12:1. When I want to to climb a steep hill, I can go 25.8:1.
Using the tallest gearing available (44:14), I can go 20mph (state's legal limit of motor-assisted bicycles) doing around 3000 rpm on the engine. So not too bad! Of course, I'd want to get in the good habit of pedal-starting to get up to the right rpm before the engine automatically engages the centrifugal clutch. Maybe a start from stand-still would be possible with the shortest gearing of 26:1. IDK, I can't wait to get it and test run it, which isn't going to be until around middle to late December.
The engine I have coming is included in a complete motorizing kit, and it's due to be here anytime from now until the 6th of Dec. Today, I rode my bike 10 miles to pick up a special kind of grease from the hardware store. It's meant for greasing the bearings of marine equipment, so it is very resistant to water and salt. Withstanding a ton of heat and rpm, this kind of grease doesn't go dry on you like your average lithium-based grease. Very tacky was the word used to describe the compound in this grease. I plan to use it inside the gearbox that comes in the engine kit, which the experienced folks in the motorbicycling community recommend you use a lot of it in order to prevent premature wear and possible breaking of the gear's teeth.
I shopped at the Do-it-best hardware store in Northbrook. There's a Korean grocery mart inside the plaza. Snow lightly sprinkled below the overhead parking lights. I have feint sentiments I recollect about the holiday season of previous times; seeing the vacant lots full of rows of cut-down ever greens for the consumers to walk through and admire brings back cinematic feelings of Santa Claus movies and the reindeer and elves. You gotta love the Midwest, especially the Great Lake states with their generally cold, wet climates. I digress...
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