Project 29er: Scooterguy Mount With GP460 Or Tanaka 47R Engine

[5-7HEAVEN]

I'm building a 29" motorized bike. It is my first effort towards a 29er; it is also my first effort of building a bike from scratch. The main reason is to see if the larger-diameter "balloon" tires will absorb road punishment and soften the ride. Hawaii has the worst paved roads in the U.S.

My "Project 29er" begins with this frame:

http://cgi.ebay.com/New-2010-Kona-U...e-and-Fork-18-/370422437266?pt=Mountain_Bikes

The new steel frame comes with a rigid fork, but I needed this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170530546015&ssPageName=STRK:MEWNX:IT

This is a key component to keep the high-rpm engine within its power range. It should also allow me to climb the extremely steep ramp at my workplace parking structure:

http://www.staton-inc.com/store/products/NuVinci_CVP_Model_N171B_Gear_ratio_350-531-20.html

I'll order these tires, which have had excellent reviews:

http://www.schwalbetires.com/big_apple

Thanks to Detonator Tuning, I have two Scooterguy mounts. One is billet aluminum; the other is steel. Thanks, Steve. I'll be researching your Scooterguy build for helpful hints.

Motorvation will either be GP460 4.25hp or 2.8hp Tanaka 47R engine. I'll try both engines to see which works better.

This will be a slow build, according to my work and school schedules and other projects. Estimated completion date is January 1, 2011.

 

[5-7HEAVEN]

In Quick Progression!

Man, Project 29er build is advancing at an extremely quickening pace. Most of the parts are ordered and on its way. I already have used miscellaneous items like handlebar, pedals, levers and stem, as well as hydraulic disc brakes, engines, trannies, Scooterguy mounts, sprockets. Completion time might be much sooner. I just need to order 8mm chain and bike cables when the time comes.

Waiting for the rims to arrive, so I can order 11-gauge spokes. My local bike ship will supply the front hub and assemble the wheels. I trust his work and customer support, but it took him a lonnnnng time to complete wheels I'd ordered before.

I've decided to run the GP460 engine in Project 29er. My 26" Diamondback bike mounts a Tanaka 47R engine. If I use the spare Tanaka in this build, I might have to cannibalize one engine to fix the other. Both bikes will use 8mm chain and drivetrain sprockets, bike chains, front derailleurs and SBP Jump Stops. The gear ratios are slightly different, because I'm just using spare sprockets for this project. They'll work just as well.

For those interested in the technical information, I'm using Detonator Tuning's former Scooterguy mount/460 engine project as a guideline. However, I'm not as precise as Steve was in creating a close-ratio transmission(cassette). My 5:1 pocketbike tranny connects to a 14-tooth sprocket, which chains up to a 72t driven chainring. This calculates to 72t/14t = 5.143 X 5(tranny) = 25.71:1 primary drive. The second chainring is 36-tooth bike sprocket, which connects to a 16-tooth cog on the NuVinci rear hub. This DECREASES gear ratio to 16t/36t = .444:1; multiply 25.71 X .444 = 11.427:1. Fortunately, the NuVinci's 350%(3.5:1) INCREASES gear ratio from 11.427 X 3.5 = 40:1 in its lowest gear position.

My 26" DB bike has a first gear ratio of 41.65:1 with its 8-speed cassette. When you consider the Project's taller 29" tire, in comparison this lowers the 29er's lowest gear position of 40:1 to 35.89:1. That's a 10.1% drop in gearing throughout. However, the NuVinci hub has a extremely wide gear ratio range of 3.5:1 to .5:1 to compensate for any differences. Besides, 35.89:1 is still a stump-pulling first gear.

With the NuVinci hub, in comparison with my Diamondback's 8-speed gears and 26" tires, the NV's range on Project 29er will be from 3.5 to 1.399:1.
The lowest gear position of 350%(3.5:1) is midway between the DB's first and second gear, which is a good thing.

My shift kit is a mix of Sick Bike Parts crankset, Jump-Stop and a 36t chainring with plastic guard. I'll get the wider cartridege from my LBS. However, I'm using an electric scooter's 4-bolt freewheel to mate the 72t chainring to the crank. My 26" DB bike has 8mm drivetrain and chainring sprockets from electric scooters, and I prefer the stronger 8mm T8F chain. The only machine work necessary is to simply drill the SBP's 36t chainring sprocket to match the freewheel's 4-bolt pattern.

I'll ask my friend Hawaii Ed to take pictures when the time comes.

To be continued...

 

[spad4me]

You are not going to like the life expectancy that the 4 bolt freewheel gives you.
They are high maintenance compared to the ENO freewheel that sick bike parts sells.
The clamping method that sick bike parts uses is superior.
Not only are the freewheel pawls weak .
I have peeled the threads off both because the 4 bolt freewheel spun
No problems after I switched to the ENO though

 

[5-7HEAVEN]

Thanks for feedback, spad4me.

I'm presently running this 4-bolt freewheel with 8mm sprocket on my Diamondback bike. So far so good after maybe 100 miles. I'm liking 8mm chain drive, decided to use the same on Project 29er for similar reasons. I couldn't find 36t in 4-bolt pattern so will drill SBP's 5-bolt sprocket to match the parts.

If these 4-bolt freewheels fall apart, then I'll switch to SBP's 'wheels. No need for the HD one...yet.

Still waiting on parts. All I have in possession is the NV hub.

 

[5-7HEAVEN]

Update: still waiting for the Kona 29er frame and suspension to arrive from two different ebay sellers, via Parcel Post. Schwalbe Big Apple street tires, tubes, Velocity rims, sprockets and freewheel got here last month. I need to buy 8mm chain, front disc brake hub, cables and miscellaneous items.

Anxious to see what the Kona Unit single-speed frame looks like, up front.

Hopefully, the 18" frame will be big enough for the engine, and small enough for my short legs.

 

[Lance Portnoff]

good luck with ur new build

 

[5-7HEAVEN]

Thanks, Lance. Most of the parts are here, but the rims have not been assembled yet. Still fine-tuning my other project, a 26" bike with Scooterguy mount/4.2hp engine.

 

[skrufryder]

Hey
Those Big Apples are great you'll be very happy with them

 

[5-7HEAVEN]

Thanks. My friend Hawaii is using these tires, but in 26" size. I was fortunate to find these. Not many road tires made in this size, which is actually 28".

 

[5-7HEAVEN]

The Build Is On!

It's Time!

I'm on vacation from school and work until January 11, 2011. This gives me time to start building Project 29er. I also moved into another residence, allowing me extra workspace.

Velocity rims/wheelset needs to be built from scratch with disc brake hub and NuVinci rear. Local bike shop is qualified to assemble the wheels at reasonable cost.

Through my previous build w/GP460 engine and shiftkit, I learned that the 8-speed bicycle chain was the weakest link. So as not to repeat months of trial and error, the strong, affordable #420 chain will harness power from 36t chainring to 18t on NV hub. The 8mm chain and drive/chainring sprockets have been very dependable on my 460 MB, so I'll use it for Project 29er too.

Engine choice is between 2.8hp Tanaka 47R and 4.2hp GP460. Both are fantastic, powerful engines, but I'm leaning towards using the Tanaka powerplant. This would be a reasonable way to compare its dependable reputation with the supposedly unreliable China 460.

I'm on it!