BMP saved

[rawly old]

Well Hap,
Since you asked, here's the mockup of my belt drive kit using
an old friction drive. Did I mention I already had the aluminum
drive ring. My apologies, Silvaire, it's not from a 24" whl. Guess
I never really measured it. It's off a 20"; anyway, it's the same
diameter as a GEBE but sturdier. I used it on a homemade elec-
tric kit that had the heater fan motor from a scrapped bus, a
stereo rheostat, and 2 SLA motorcycle batteries. It worked surpris-
ingly well, but the range was disappointing, and all that lead was
heavy and unwieldy.
I don't want to be accused of cloning a GEBE, so there'll be no
timing gear or cogged belt, just an old fashioned V-belt.
I paid Lucky Early Bird,(BGF), $199 + free shpg. for the kit, engine
and all. Apart from being loud, the HF engine is really something.
Unfortunately, it's way too powerful for the components that came
with the kit. The bearings blew out and the clutch drum warped
shortly after break-in. Harbor Freight lists their auger engine at
1.5 hp, but they must have arrived at that figure cuz it's 1 1/2
times faster than a horse. This thing is a brute; it's gotta be
closer to twice as powerful as my GX35. It pulls smooth and easy
with the plug out, but put one in, and you'll rip your rotator cuff
starting it. The compression has to be 9 to 1.
Anyway, pic.1 is the freebee shaft I got for haulin' away a
defunct lapidary setup from an estate sale. The smooth portion
is the exact length and to fit the BGF now that I've installed
good bearings. Whats cool are the shaft nuts the narrow side
of which has 2 flat side like a whl. cone. They can themselves
be configured into pulleys. Counting the pulleys I already have,
I can use .625", .875", 1", 1.25",and 1.375" changing as needed
in less the 2 min.
Pic.2 was meant to show that my belt will clear the seat stay
by 3/4" and the strut by 1 1/8", you can't tell from the pic.
Pic.3 is a profile which shows also a cpl. other pulleys and
the grips I've made using a layer of closed cell foam, alligator
hide, and the spoke mounts from a 16" whl.
What I'm waiting on now is a stouter clutch drum,a belt, a
decent spacer, and 18 #12 gage spokes for the drive side.
Once it's all buttoned up, it may not get quite the mpg of
GEBE, but I guarantee it'll outrun and out climb one. The
total outlay with shpg: $273.12 + $14.95 for the grips.
Can't seem to get shaft pic to load

 

[rawly old]

Oops!

 

[rawly old]

Forgot to add the cost of rethreading the shaft down to 3/8"/24
for the clutch drum, but my last thread job was under $10.

 

[Silvaire]

It's looking good Rawly,

I have nothing against using the ideas of others on your own projects, but it can get sticky when someone applies those ideas commercially - whether the ideas have some form of legal protection or not.

(GEBE states "PROTECTED BY U.S. PATENT LAWS" on their website. I suspect this is likely bluffery on their part, a weak unenforceable patent, or most likely that they use components in their product that are patented - such at the patented Gates belt tooth profile - which anyone else could also buy and use. I don't think it is morally right to copy the EXACT DETAILS of someone else's work for your own COMMERCIAL product, although doing so might be perfectly legal.)

I like the idea of using a smaller rim as a large sheave. If you have only the single speed reduction though, I would still consider using a toothed pulley and belt to drive it GEBE style. The concern I would have is that the driving pulley needs to be a very small diameter - with likely too sharp a bend for the "V" belt to efficiently handle. On the other hand, the wide flat face of the toothed belt might not work well in the concave profile of the rim/sheave as it would have a tendency to walk up the the sides.

Anyway, keep us posted on your progress.

 

[rawly old]

Thx Silvaire,
just posted a fairly lengthy reply, but somehow it seems to have been hijacked to
administrator or sumpin. there was nothing objectionable in it; I think I just musta hit the
wrong button.
Anyhow,the gist was that happily the 1" pulley, drive ring, and belt from my old
electric kit all fit, and have already been proven to work just fine.
As far as GEBE's "patent is concerned, belt drive bikes have been around for more
than a 100 years, and having some knowledge of patent law, I've not infringed on
anything GEBE can claim is uniquely theirs. If anything, I could likely claim that
my adaptation from channel drive to a direct pulley driven wheel is unique. It's
probably not. It doesn't matter. I'm not in for the money. I'm just out to own the
best system I can make with what I have.
I hope to have complete working model to show soon and to report performance of same.

 

[lowracer]

Rawly old,
I think your gearing may be too tall?
I ran a whizzer sheave on a MTB wheel w/ 1.5" engine pulley & the engine couldn't get into its powerband. I needed a larger wheel pulley to correct the gearing.
If you roll the bike one complete wheel revolution (valve stem to valve stem), how many revolutions does your engine pulley turn?
-Lowracer-

 

[rawly old]

I think you're right. 1.5 is insanely out of the question. I'd have to be doing 22mph
before the clutch fully engaged if I hadn't already ripped the spokes out by then. I
never seriously considered 1.5; it was just something i had the means to do.
Silvaire's right about using a small pulley. Actually, I was thinking 1". I have a way
to make 5/8" work without a cogged belt or gear, but, though I'd still have more
power than a GEBE kit, my top mph would be about the same.
With 1" I'd be engaged at about 14 mph, which is doable but still a bit high. So...
I think I'll try 7/8" first. This should still yield a top end of about 32 mph and still
offer good acceleration.
In answer to the question, the 1.5 would have about a 9.8 to 1 ratio, which is
absurd when one considers a theoretical top spd of 60+. (not that that's ever
gonna happen)

 

[occchopperfl]

BMP Website finally disabled...

I feel abandoned.

Sigh...

 

[rawly old]

I know; try not to take it too hard. Think positive; at last you can stop
looking longingly at stuff you'll never be able to buy.

 

[Deleted Member 4613]

Don't understand why someone couldn't keep BMP going on a part time basis. They had some very good concepts, like chain drive.