how do you go about getting in the over 50 mph club.

[Street Ryderz]

Lets look at the gearing on the shift kit compared to a single gear,I know that some of the Zeda's now come with a 36t gear but I still consider the 44t as a stock gear witch gives a ratio of 18:1 this ratio allows a stock engine to accelerate and not be over loaded.The shift kit comes with a 17t on the left side (engine) and a 10t on the right to the chain ring being 48t and the drive is a 36t to the wheel's gears that are commenly 28-14,So the first gear being 26:1 second gear is 22.3:1 third gear is 20.4:1 forth gear is 18.6:1 fifth gear is 16.7:1 sixth gear is 14.9:1 and seventh gear being 13:1 .Now 13:1 is the same as a 10-32 single gear and how many stock engines can turn a 10-32 gearing and spin it up to 9 grand?None that I've seen turn lower than the 36t upto or over 9 grand.

 

[gary55]

Especially a bone stock engine with a bone stock head, carb., pipe, and the added resistance of the j shaft. There is no way in hell it will pull 50 like that. with some good bolt ons and engine work It could easily.

 

[FurryOnTheInside]

According to a quick calculation I just did on http://bikecalculator.com you need about 4.5 horsepower to sustain 50mph using mountain bike tyres and in the bar tops riding position. Of course it takes even more to accelerate to 50mph. What does the stock Grubee produce?

 

[Steve Best]

According to a quick calculation I just did on http://bikecalculator.com you need about 4.5 horsepower to sustain 50mph. Of course it takes even more to accelerate to 50mph. What does the stock Grubee produce?

About 1.5 hp but that 4.5 hp figure is highly variable too. Tires, clothes, physique, lubes, and aerodynamics all figure in and 50mph could be reached with very little hp (3hp?) if everything was optimized. On the other side, 4.5 hp is not hard to obtain from a 66cc 2-stroke air-cooled engine either.

 

[FurryOnTheInside]

About 1.5 hp but that 4.5 hp figure is highly variable too. Tires, clothes, physique, lubes, and aerodynamics all figure in and 50mph could be reached with very little hp (3hp?) if everything was optimized. On the other side, 4.5 hp is not hard to obtain from a 66cc 2-stroke air-cooled engine either.

It was a very rough figure, yes. A quick, casual, ball park estimate of the power needed for the bike pictured above to sustain 50mph.

Unfortunately I will never really know my mechanical resistance or drag coefficient, or the power output of my engine, only the end result. And I don't know anywhere I can ride motorised at 50mph anyway! I was just playing around with the calculator.
I played around with the variables it allows and couldn't get it to 1500W at 60kph so my waterproof jacket must have been holding me back, lol.
I have started thinking that 4.5hp from the 66 is difficult and would require not just a tuned pipe and the other common, easy mods, but also case stuffing or one of the engines with less crankcase volume.
So I will try to improve the aerodynamics so that less power is required. That's more in my skill set.

 

[Tyler6357]

About 1.5 hp but that 4.5 hp figure is highly variable too. Tires, clothes, physique, lubes, and aerodynamics all figure in and 50mph could be reached with very little hp (3hp?) if everything was optimized. On the other side, 4.5 hp is not hard to obtain from a 66cc 2-stroke air-cooled engine either.

Really? only 1.5 hp? Wow, I thought it was closer to 2.5 hp

 

[Deleted member 26224]

These are all small potatoes. I have a lil 175cc 2-stroke 5sp sittin here and wonderin what to build.

 

[FurryOnTheInside]

These are all small potatoes. I have a lil 175cc 2-stroke 5sp sittin here and wonderin what to build.

Something stronger than most bicycle frames, lol.

 

[KCvale]

Kc what are your thoughts of a drum brake? Specifically up front

A Drum brake is fine up front,it beats a pull caliper I think.

 

[crassius]

seems quickest way to go 50mph is to get hit from behind by a car going 60mph