Gear Ratio Benefit of Grubee Belt Drives

Sidewinder Jerry

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So if I have that same setup with a 11-34 freewheel, & buy a grubee shift kit, what kinda speed is a guy looking at? Can I pick up some speed with installing the grubee 10g shift kit. I could do the math, but you always seem way quicker at doing it. 🤣😂🤣 What speeds in conjunction with what gear you have selected? Thanks Sidewinder!!!
You probably aren't going to up your top end level ground speed but will be able to up your average speed due to having a wider reduction range. You'll find you can climb hills faster and will be able to engine assist to a higher speed quicker going down hill before gravity takes over.
 

Sidewinder Jerry

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So if I have that same setup with a 11-34 freewheel, & buy a grubee shift kit, what kinda speed is a guy looking at? Can I pick up some speed with installing the grubee 10g shift kit. I could do the math, but you always seem way quicker at doing it. 🤣😂🤣 What speeds in conjunction with what gear you have selected? Thanks Sidewinder!!!
If the Gru-Bee shift kit is like the SBP shift kit it'll be (5:1)(9/17)(9/48)(36/34-11). This'll give you a reduction range of 47.57:1 to 15.39:1. The 142 engine produces about 1.6 horsepower therefore around 18:1 reduction is about as low as you should go on level ground. That's around what you'd have with the 7th 13t cog on the 8 speed DNP freewheel. The 8th 11t cog would be only used going down hill. You should throttle back once you hit 38 mph going down hill. Your engine is no longer contributing to your speed and gravity acceleration has taken over.

Your take off gears will be (1) when going up hill and (3) for all other take offs. In other words if you have to stop going up a hill shift to (1) before stopping. Shift to (3) before stopping on all other stops.
 

Mike St

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I just learned it is possible to replace a 100T Chinese ebay belt
drive tranny sprocket with an 80T sprocket from bicycle-engines
which would reduce the ratio from 5:1 to 4:1. The smaller 80T
belt would have to be installed.
 

Sidewinder Jerry

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I just learned it is possible to replace a 100T Chinese ebay belt
drive tranny sprocket with an 80T sprocket from bicycle-engines
which would reduce the ratio from 5:1 to 4:1. The smaller 80T
belt would have to be installed.
Yes you can do that but I'd only recommend flat lander lite weight riders do it.
 
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