Have a 2008 Harley Dyna Street Bob I am attaching sidecar too. Noticed the bike was geared kind of high and dont want to lug the sucker should I put a smaller tranny sprocket on front? It is belt driven.
There are different rear wheel sprockets available. Earlier big twin belt drives had 70 tooth (US) and 61 tooth (Int'l.) sprockets. I think the '08s dropped to 64 tooth to give the 6 speeds better performance.
Any rear or transmission sprocket change may also require a different length belt which is not a quick switch.
Different motor sprockets and clutch baskets are also available from many after market vendors.
Lonnie
Northwest Sidecars
just two thoughts,
with a car tire you get a ratio reduction too.
With toothed belts you have to take care not to go too small with the sprocket. With very small radios and way higher torque on the sprocket you are able to rip off the teeth from the belt's core.... Looks and SOUNDS impressive when a CNC table runs into the solid end stop at max speed (after a current spike)..... that was the way I found out on that one.
Regards
Sven Peter
Some have converted belt drives to chain drives to allow easier final drive gearing. The chains do better if run on gravel roads also.
Lower profile tire in rear will help final overall gearing also if you can find one. Smaller tire may wear quicker though.
Going to a car tire conversion has it's merits. With a 15" car tire you have a pretty good choice of tire diameters to deal with final rubber to the road gearing. Milage figures with car tires can be quite impressive compared to cycle tires on the rear of a sidecar pulling bike.
Is there any particular gear ratio or percent of total gearing drop to shoot for when regearing? I'm trying to figure out gearing on my CB750A as well. It was kind of overwhelmed by the hills/headwinds on the way to the GP.
Different bike/sidecar combos have different power bands, loading, usage and final drive ratios. Regearing for best performannce is an individual choice. Some want more road speed and some want more grunt at the startout.
If your CB has chain drive that is the easiest and cheapest to change at the rear sprocket. Add a few teeth then add a few chain links.
Lonnie
I changed to 3.37:1 for my 2004 Ultra with HD TLE sidecar. That was an easy change because stock parts are available. I changed the motor sprocket and the clutch basket.
Unfortunately, AFAIK, there are no stock parts available for a late-model Dyna gearing change. It is possible that there are primary sprockets available for a Dyna in the aftermarket. That would be my first choice.
If you change the rear pulley combination, you will affect the speedometer reading. It's possible to get a calibration unit for the speedometer but they are pricey. Any change you make is liiable to require a belt change and that's not inexpensive, either.
In any case, you would want something lower than 3.0:1 for your 96" engine. I really like the slightly lower gearing on my bike. It's the same ratio that was used on most of the Evolutioin bikes.
Good luck.
Thanks for the ideas. Think I am going to try it the way it is for a while and just remember to keep the revs up in a higher gear. If I notice some problems with the lugging, not sure exactly what they would be, I might look into the aftermarket for a new front sprocket and belt.
I've had a hard time finding sprockets for the CB. It has 630 chain and all I could get for a reasonable price is one tooth less than stock when I built the bike. Sprocket Specialists has more options available at over $80 each, or a one tooth smaller front for $25, which is probably what I'll try to see how it works. One tooth down in front is about a 7% reduction, if I did the math right. Having the automatic version makes gearing a little weird anyhow, since I've only got two gears to choos from when riding.
