Motorized Rocky Mountain RM7 -Super Motard-

Hi,
I finally got my winter project ready to ride...I decided on a Subaru-Robin 4 stroke 35cc & Front belt drive powertrain providing 2 wheel drive (since I am an avid cyclist & enjoy pedaling). The front drive is a rim hoop, JB welded to the front rim & an automotive standard notched 78" V-Belt with a skateboard wheel tensioner & a 1.5" front V-pulley from McMaster Carr. The gear ratio is similar to a friction drive without the need for jackshafts or further reduction.The mount is just some steel bar & 'L' brackets found at the local Lowe's Home Improvement store. I wanted to keep this project cheap & under the price of any kit available such as Gebe/BMP/Staton/Friction & with no welding. I am good at hacksawing & drilling but nothing more hi tech than that...lol. I got the new Subaru engine/clutch housing from Staton off eBay w/Bing discount for $248 & the rest was under $50. The throttle is a bicycle brake lever mounted to the left side handlebar above the front disc brake lever. The 7" front suspension still works perfectly & well matched to the 7" travel suspension in the rear...
-Lowracer-
 

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Front Wheel Drive Set-Up

Is well thought out and looks to be very KISS functional. My compliments.

How easy is it to ride without motor running, etc?
 
Hive,
Thanks for the compliment.
I've run out of gas twice now & had to pedal home. Its fairly easy to ride unmotored perhaps requiring 2 easier gear clicks to compensate for the additional drag of turning the vbelt & centrifugal clutch housing. I'm not too sold on the benefits of front drive & need to try rear drive. I took it all apart yesterday & started the rear drive project I mentioned in my last reply. I'm going to use the same Robin EH035 to start with & see how I like rear drive as opposed to front drive. Since I like to do things on the cheap, I only needed to spend about an extra $90 for the conversion (Whizzer sheave, Steel strut material, new VBelt, Solid rear axle replacement) The rest of the stuff I already had laying around. It will use a handlebar stem mounted backwards on the 27.2 seatpost w/28.6 shim as the front engine brace. Will post pics once completed...
-Alex-
 
Rear vs Front Drives for Rack Mounted Power

My experience suggests that the rear motor needs to be mounted as close the rider or center of gravity as possible to reduce forces while turning.

It is curious that so many people do not set engine closer to seat. Easy to drill a couple holes in the bar and reattach...

The off center weight will show up at steering and if shock forks, will cause some shimmy and pitch, which can be dangerous.

If closer to rider, the opposing forces seem less but are still present.

Of course, if speed is not excessive, the problem is more or less insignificant. Vertical engine placement is also esthetically more pleasing.

I rode a front engine bike as a kid, it was a very simple friction machine called a Travis that was competing with Whizzer on Lawrence Avenue. I recall that it was okay but we were light weight kids and I am not so sure the same would be the case today.

It would be interesting to read your take on the difference.

I made a comment here http://www.motoredbikes.com/showthread.php?t=5751&highlight=Hive
And somewhere else I cannot locate.
 
Hive,
I have the rear engine already mounted & it is very close to the rear of the saddle & as low as possible for cg. I am waiting on the 65" Vbelt to come this week & can then 'Ride That Thing' as someone else likes to say..lol Will also post pics and comments after putting on a few miles...
-Alex-
 
I got the rear drive all together & took it for a test spin. By putting the engine closer in & nearer the saddle, the hotter the exhaust feels on my rearend. I had to move the engine slightly back & more vertical to avoid heat problems. I may need to change rear wheel size from 700c/29'er now to a smalled diameter 650c for better gearing. It is geared a bit too tall, but not by much. I'm sure if I put on some aero bars & the carbon 650c fork I have laying around it will surely work...Looks like its back to the garage for some more tinkering...
-Alex-
 
Rear vs Forward Engine

You are really into it. I had a minor heat problem when I had the CNC Trek cruiser, but left it.

If I moved that engine to vertical, I would not be able to check or fill the oil, as I recall, unless I stood the bike on end. Perhaps a 26-inch wheel will move the exhaust down a bit. I suspect you have encountered a similar problem.

That front fork is awesome. If I had had one of those on the CNC and a 33 Tanaka (power and no oil fill issues), would have likely kept it.
 
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I switched the Robin EH035 back to the front of the Rocky Mountain RM7 & that is where it will stay. I definitely like front drive better than rear drive & I like the big heavy full suspension bike better than the lightweight titanium 18 lb bike for Motored Biking. I have moved the engine a few inches closer to the fork & perpendicular to the ground for improved handling & aesthetics. I cutaway the engine cover to expose the little air cooled engine & allow better cooling at 30-40 mph. (See Pic)...Next I am thinking about adding some coroplast body fairing & front bubble to see how fast & how many MPG's a sub 2hp engine can achieve on an MB. We'll see if that project ever happens???...
 

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that's a nice looking bike as far as the bike goes....but man it looks so front end heavy with that motor up there like that.
you have the drive hoop (rim) j.b. welded to the front rim?
hmmm, good luck with that working for a long peroid of time.
 
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Since this picture was taken, I took the advise of fellow MB.com users & drilled 4 holes straight thru both wheel hoops & bolted them together with stainless steel hardware & nylock bolts. No worries now about the JB Weld coming apart...As far as the front drive, It isn't heavy at all. The bike weighed 42 lbs before I added the engine & hardware. The bike is designed as a downhill MTB & has a rear biased geometry & a high bottom bracket for going downhill fast & bumpy. I actually lowered the forks in the triple clamps over 2" to put more weight on the front & lower the cg & along w/replacing the knobbys for slick tires it handles surprisingly well on the road.
 
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