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Makes And Models => Zero Motorcycles Forum | 2013+ => Topic started by: MorbidBBQ on September 12, 2016, 08:39:23 PM

Title: Calculate HP after gear swap.
Post by: MorbidBBQ on September 12, 2016, 08:39:23 PM
My 2013 Zero S has the 98T/25T gearing instead of 132T/28T stock.

This gives it a higher top speed, but less acceleration.

The specs say the rear wheel torque drops from 321 ft-lbs to 267ft-lbs, but I cant figure out how HP is affected.

I know how to calculate rear wheel torque by the gear ratio and engine torque, but not HP. 

Help?

Stock HP is 54hp @4300RPM.  I assume thats motor, not rear wheel.

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Title: Re: Calculate HP after gear swap.
Post by: MajorMajor on September 12, 2016, 08:52:32 PM
afaik, gearing only affects torque, not HP.

edit: link
http://www.superstreetbike.com/how-to/bigger-rear-sprocket-makes-more-horsepower-mythbusters (http://www.superstreetbike.com/how-to/bigger-rear-sprocket-makes-more-horsepower-mythbusters)
Title: Re: Calculate HP after gear swap.
Post by: MorbidBBQ on September 12, 2016, 09:02:47 PM
afaik, gearing only affects torque, not HP.

edit: link
http://www.superstreetbike.com/how-to/bigger-rear-sprocket-makes-more-horsepower-mythbusters (http://www.superstreetbike.com/how-to/bigger-rear-sprocket-makes-more-horsepower-mythbusters)
I read that same link, the test results show there is a small change to HP +/- ~4HP for the GSX-R 1000.

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Title: Re: Calculate HP after gear swap.
Post by: MajorMajor on September 12, 2016, 10:21:10 PM
That's a 1% difference though.
I'd say functionally no difference, even if the test was 100% accurate.
Title: Re: Calculate HP after gear swap.
Post by: MorbidBBQ on September 12, 2016, 11:18:35 PM
In the link, why does torque go down with the `wheelie` gearing?  Isn't the purpose of changing the gears in that way to turn the torque up?

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Title: Re: Calculate HP after gear swap.
Post by: MajorMajor on September 13, 2016, 01:00:44 PM
I'm by no means an expert on dynamos but I'm guessing that they're dividing the torque result by the gear ratio.
The small variance in the figures could be caused by the ICEs powerband changing slightly with different loads (again guessing).
Title: Re: Calculate HP after gear swap.
Post by: Patrick Truchon on September 15, 2016, 07:52:53 AM
There was a bit of a debate on the forum a while back about how the different gear would affect range (which is related to Energy consumption, which is related to Power usage, which is what you mean by "HP").  I ended up running an experiment (http://ptruchon.pagekite.me/wiki/blog/2015-09-19/does_gear_size_affect_range) with an electric drill (doubling the "gear" size) and found no significant difference.
Title: Re: Calculate HP after gear swap.
Post by: MorbidBBQ on September 15, 2016, 07:50:39 PM
There was a bit of a debate on the forum a while back about how the different gear would affect range (which is related to Energy consumption, which is related to Power usage, which is what you mean by "HP").  I ended up running an experiment (http://ptruchon.pagekite.me/wiki/blog/2015-09-19/does_gear_size_affect_range) with an electric drill (doubling the "gear" size) and found no significant difference.
Good info, thanks!
Title: Re: Calculate HP after gear swap.
Post by: MrDude_1 on September 16, 2016, 02:15:51 AM
There was a bit of a debate on the forum a while back about how the different gear would affect range (which is related to Energy consumption, which is related to Power usage, which is what you mean by "HP").  I ended up running an experiment (http://ptruchon.pagekite.me/wiki/blog/2015-09-19/does_gear_size_affect_range) with an electric drill (doubling the "gear" size) and found no significant difference.
Hey, I know you... kinda... I read your whole website a few weeks ago when I was looking up info about it. lol.