Will shift kit help with strong headwinds?

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wheelbender6

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Sep 4, 2008
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I was only managing around 12 mph against the headwinds in Houston today on my China girl (I normally cruise at 25 mph). Aero mods could probably get me 2 or 3 mph. Would a shift kit help by allowing to select a gear where I can maintain max torque rpm? I also considered just installing a derailleur/cluster and adding good old human power in the headwinds.
 

5-7HEAVEN

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Aug 2, 2008
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I was only managing around 12 mph against the headwinds in Houston today on my China girl (I normally cruise at 25 mph). Aero mods could probably get me 2 or 3 mph. Would a shift kit help by allowing to select a gear where I can maintain max torque rpm? I also considered just installing a derailleur/cluster and adding good old human power in the headwinds.
Yes, a shift kit with low gear ratios will definitely help in headwinds and steep hills. Keep in mind that human power doesn't help much, when the engine is driving the same chain.

You could also buy a generic windshield from a Chinese scooter on ebay. They are relatively cheap and easy to install.
 

killercanuck

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Dec 17, 2009
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Shift kit will definitely keep you in the power band. Unless you've got a single speed rear hub, lol.

I've got 7 gears to play with, going into wind 3rd or 4th... coming back with the wind 7th, all at same engine rpm :p Same with towing or bastid hills, 1st, 2nd

A 'shield would be more for comfort than extra speed wouldn't it? Depends on the shape of it I guess, eh?
 

The_Aleman

Active Member
Jul 31, 2008
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el People's Republik de Kalifornistan
Having optimum pedal gear ratios and the willingness to pedal will greatly enhance the riding experience on these!
Gear cluster and 50+T crank sprocket, keep pedaling at 28 :D

As for shift kits, setting a shift kit up so that you can contribute your pedal power at the optimum time is the way to go. By default, the shift-kit puts your "pedal" redline way below the HP peak. To counter that you must run a huge (60+) outer crank sprocket to increase the engine gear reduction.
 

5-7HEAVEN

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Aug 2, 2008
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Having optimum pedal gear ratios and the willingness to pedal will greatly enhance the riding experience on these!
Gear cluster and 50+T crank sprocket, keep pedaling at 28 :D

As for shift kits, setting a shift kit up so that you can contribute your pedal power at the optimum time is the way to go. By default, the shift-kit puts your "pedal" redline way below the HP peak. To counter that you must run a huge (60+) outer crank sprocket to increase the engine gear reduction.
Interesting.....

HOWEVER, the inside chainring is the pedalling one. Having one with less teeth results in low gear ratio and good pulling power for the engine. Unfortunately, not for pedalling power and engine power simultaneously. I haven't measured it, but I don't think a 50t will fit on the inside chainring position. It will hit the chainstay frame. Also, a large bicycle chainring REALLY screws up the gear ratios for engine application. Compare these figures:

Use the 24t chainring and 9t jackshaft for stump-pulling low gear (45.43:1, like a 111t rear sprocket) and 15.62:1 in 8th gear (15.62, like a 38t sprocket).

Use a 30t chainring for 36.35:1 (88t sprocket) and 12.49(30t) in 8th gear.

Use a 36t for 30.29:1 (74t) and 10.41:1 (25t) in 8th gear.

Use a 50t for 21.8:1 (53t) and 7.5:1 (18t) in 8th gear.

In retrospect, this 21.8:1 first gear w/50t sprocket is similar to 6th gear (21.3:1) with a 24t chainring.

To summarize, if you could get a 50t bicycle chainring to fit a bike w/shift kit, it would not be a good choice for engine power.

But hey, that's only my calculated opinion. We can all agree to disagree.....until someone actually installs a large sprocket as their bicycle chainring..shft.

A 60t engine chainring? Lemme do more pencil-scratching, lol.

Ok, with a 60t engine chainring and 9t jackshaft, that's 31.02:1 in 1st gear w/34t sprocket (like a 76t rear wheel sprocket).

In 8th gear, that's 10.22:1(like a 25t sprocket).

You can pedal well in 8th gear, but will that 50t fit in there?
 
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The_Aleman

Active Member
Jul 31, 2008
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Interesting.....

HOWEVER, the inside chainring is the pedalling one. Having one with less teeth results in low gear ratio and good pulling power for the engine. Unfortunately, not for pedalling power and engine power simultaneously.
DUH, but SBP's stock ratio doesn't favor pedal power. By default, you will arrive at pedal redline long before engine redline. This is why a larger outer crank ring is needed so you can gear down engine. If one wanted to gear up pedal, too, he would need an even larger outer crank sprocket.

I haven't measured it, but I don't think a 50t will fit on the inside chainring position. It will hit the chainstay frame.
I wasn't talking 50T for your bike. Or any shift kit bike. I was talking large chainring for use with OP's bike to go with the derailleur he was thinking about getting for his single-speed bike.

Also, a large bicycle chainring REALLY screws up the gear ratios for engine application. Compare these figures: <insert yada yada here>

To summarize, if you could get a 50t bicycle chainring to fit a bike w/shift kit, it would not be a good choice for engine power.

But hey, that's only my calculated opinion. We can all agree to disagree.....until someone actually installs a large sprocket as their bicycle chainring..shft.
Which is what I'd be doing if King's Sales & Service wasn't ignoring people right now. I need a 51/67 crank sprocket set! :D

I have a 36/48 currently. I'm gearing up pedal and gearing down engine. Looking for 60 pedal RPM @ 4000 engine RPM, 120 @ 8000.

Emphasis on assist :D
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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I hear you about King's customer service department.

The OP mentioned "shift kit", which infers multiple gears.

OP also mentioned just installing derailleur/cluster and adding good old human pedal power.
 

andrewflores17

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Jul 12, 2010
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http://www.youtube.com/watch?v=7h7AmVPpaEY&feature=player_embedded


could always try a propeller like this guy did

i think that the shift kit may help you find the best gear ratio for the wind your hitting i live in colorado and wind is my bigest killer for speed try to plan your route if you can to have some sheilding from the wind or to have it only on your side for as long as possible before going head on at it
 

breno

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Aug 19, 2010
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Syd. OZ
Be sure to post the speed difference it makes in those head winds if you go Ahead with the shift kit.:)
 

Wally

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Dec 25, 2011
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South Africa
I am as happy as a pig in ... I finally got the SBP shift kit together and took it for a spin. I had a 35 Kph head wind and it didn't even feel it. I do recommend it.