Thread: Gru Bee?
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Old 12-07-2008, 12:47 AM
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xPosTech xPosTech is offline
The Old Master Motorized Bicycle Builder
Join Date: Oct 2008
Location: SETexas
Posts: 209
Default Re: Gru Bee?

I just checked out the 4 Stroke Installation Manual at They're a little vague on some things. Another problem I have with it (the manual) is they don't know the difference between concave and convex.

Paste from the manual:

The sprocket has two sides. One side is shaped like
the inside of a bowl (convex)
. The other side is shaped like the outside of a bowl (concave). It is sometimes difficult at this point in the installation to determine whether to install the sprocket with the concave side facing in or out. This is a judgment call based on how close you want the chain to the tire when the motor is installed. In the case of the Schwinn Jaguar, the sprocket was installed concave-in (facing the bike).

I learned in elementary school that concave was dished in, like the mouth of a cave. I never had a problem confusing an inny with an outy. Apparently the guys at BEc went to a different school.

The instructions reference concave and convex when mounting the sprocket. Which leads me to question which side of the sprocket they're talking about. If you look at the inside of a bowl it's concave. Do they mean their concave or the real concave?

It sorta makes me wonder if they fudged anything else up. I think I'll just build my own kit. Well . . . at least to where it meets Pablo's kit.

I wasn't born in Texas but I got
back here as soon as I could.

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