I have been waiting a year for my custom designed quality real Grube Skyhawk parts to be made and shipped to the US to build for this newest style fat tire MB most anyone would really love riding as well as look at, and the final pieces are on their on their way... Specifically, the new real Skyhawk GT2A-150 frame!
[FONT=Verdana, Arial, Helvetica]A couple of us builders worked with Don Grube last year for upgrades to the GT2 gas tank frame and we got what we wanted.
150mm rear horizontal drop out bicycle engine frame designed for use with 2 stroke and 4 stroke engines.
Good with heavy duty disc brake axle for single or multi speed sprockets.
Compatible with coaster, caliper and disc brakes, and can accommodate up to 3" wide tires with enlarged 100mm wide front drop out area.
The real key changes here are:
The wider frame at the seat post to accommodate 3" wide tires.
The old style would only take 2 1/4"
And the the open rear horizontal drop outs with adjustable left side disc brake caliper mounts as well as a right side derailleur mount.
Like the original it also has V-brake bosses, chain guard mounts, and both upper an lower cable routing gussets, and a nice big bottom bracket hole that can take both 3-piece and 1-piece cranks.
And it is getting a 53cc HS 144F-1G 4-stroke and my 10G direct long shaft shifter transfer case and base.
In short, this Fito Modena 7-speed performance 53cc 4-stroke dual disc shifter....
... with a 2.4L (~2/3 gallon) gas tank in the frame and an internal 3-speed rear hub for motor shifting ;-}
I am bending to the customers will and using a dual spring Monarch disc fork, and sacrificing a new single speed Fito for the wheels and front disc brake.
The back wheel hub is getting a 3 speed disc hub anyway so no loss with that.
Going to use the fenders and seat too but that's about it.
The customer wants a black stealth look, easy, the next one won't be so plain ;-:
The really hard things to understand for most...
A typical 2-stroke MB engine has a built in ~4:1 gear reduction and manual clutch.
This is ideal logically to add a drive system to the rear wheel leaving the pedal system intact by a separate left side drive system.
But it's direct drive, single speed, like a 4 cylinder 3-speed manual Yugo or Gremlin stuck in 2nd gear.
I know that is over most young peoples heads but my best first hand analogy of how crucial gears are on weak engine.
Sure you can eventually get to speed without 1st but not entering traffic, and then you top out in speed because you can't shift to 3rd.
That is the fact in everything related to ground transportation , gears help, but only in proportion to input power and the gear ratios.
A 1:1 gear ratio for bikes is one revolution of the pedals equals one revolution of the rear wheel.
Tire size matters here!
Gear systems have two ratios relative to 1:1, the max reduction it has in low, and the max overdrive it can do it high.
Typically the low gear is ~33%, 3:1, meaning you have to pedal around 3 times to get one full rotation of the back wheel.
High gear can be up in the 1:5 range, meaning for every for every full pedal the back wheel spins 5 times.
A doped up Lance Armstrong on his best day only has 1/10th HP so he needs a lot of little gear steps to gain speed and keep his legs in HIS personal 'sweet spot' at the time.
A 2-3 HP engine doesn't need a whole bunch of gears in between low and high like Lance, I find 3 to be just right.
3:1 low, 1:1, and 1:3 high.
How that relates to speed and torque is all about sprocket sizes, but the references are all related to 'pedal turns:tire rotations' 1:1 baseline.
I hope that helps some of you with the concept of gears ;-}
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[FONT=Verdana, Arial, Helvetica]A couple of us builders worked with Don Grube last year for upgrades to the GT2 gas tank frame and we got what we wanted.
150mm rear horizontal drop out bicycle engine frame designed for use with 2 stroke and 4 stroke engines.
Good with heavy duty disc brake axle for single or multi speed sprockets.
Compatible with coaster, caliper and disc brakes, and can accommodate up to 3" wide tires with enlarged 100mm wide front drop out area.
The real key changes here are:
The wider frame at the seat post to accommodate 3" wide tires.
The old style would only take 2 1/4"
And the the open rear horizontal drop outs with adjustable left side disc brake caliper mounts as well as a right side derailleur mount.
Like the original it also has V-brake bosses, chain guard mounts, and both upper an lower cable routing gussets, and a nice big bottom bracket hole that can take both 3-piece and 1-piece cranks.
And it is getting a 53cc HS 144F-1G 4-stroke and my 10G direct long shaft shifter transfer case and base.
In short, this Fito Modena 7-speed performance 53cc 4-stroke dual disc shifter....
... with a 2.4L (~2/3 gallon) gas tank in the frame and an internal 3-speed rear hub for motor shifting ;-}
I am bending to the customers will and using a dual spring Monarch disc fork, and sacrificing a new single speed Fito for the wheels and front disc brake.
The back wheel hub is getting a 3 speed disc hub anyway so no loss with that.
Going to use the fenders and seat too but that's about it.
The customer wants a black stealth look, easy, the next one won't be so plain ;-:
The really hard things to understand for most...
A typical 2-stroke MB engine has a built in ~4:1 gear reduction and manual clutch.
This is ideal logically to add a drive system to the rear wheel leaving the pedal system intact by a separate left side drive system.
But it's direct drive, single speed, like a 4 cylinder 3-speed manual Yugo or Gremlin stuck in 2nd gear.
I know that is over most young peoples heads but my best first hand analogy of how crucial gears are on weak engine.
Sure you can eventually get to speed without 1st but not entering traffic, and then you top out in speed because you can't shift to 3rd.
That is the fact in everything related to ground transportation , gears help, but only in proportion to input power and the gear ratios.
A 1:1 gear ratio for bikes is one revolution of the pedals equals one revolution of the rear wheel.
Tire size matters here!
Gear systems have two ratios relative to 1:1, the max reduction it has in low, and the max overdrive it can do it high.
Typically the low gear is ~33%, 3:1, meaning you have to pedal around 3 times to get one full rotation of the back wheel.
High gear can be up in the 1:5 range, meaning for every for every full pedal the back wheel spins 5 times.
A doped up Lance Armstrong on his best day only has 1/10th HP so he needs a lot of little gear steps to gain speed and keep his legs in HIS personal 'sweet spot' at the time.
A 2-3 HP engine doesn't need a whole bunch of gears in between low and high like Lance, I find 3 to be just right.
3:1 low, 1:1, and 1:3 high.
How that relates to speed and torque is all about sprocket sizes, but the references are all related to 'pedal turns:tire rotations' 1:1 baseline.
I hope that helps some of you with the concept of gears ;-}
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