Sick Bike Parts - 2022

Urban Fatbiker

Active Member
Joined
Jan 30, 2019
Messages
211
48cc 2-stroke and Hookworms 26 2.5”.

(my edits piling on...Buzzbike hardware held up well to today’s bashing...fatbiker’s hardware is beaten up)
 

Sidewinder Jerry

Well-Known Member
Joined
Mar 14, 2011
Messages
3,059
I’m sad. But happy I got shifty today, my bike is fully operational.

I do need to bring my engine gearing ratio matched to cadence, I’m pedaling over 90rpm at less than mid-throttle, need that down to 60?
I'm going to explain how shifting works with a shift kit. It's based more on full throttle than it is on cadence assist. You have two primary rpms to be concerned with at full throttle; they're max horsepower rpm and max torque rpm.

If at full throttle your tachometer is going way over max horsepower rpm then you need to shift to a higher gear. If you're in the highest gear and still going over max hp rpm then throttle back some.

If at full throttle you're in a gear and can't reach max torque rpm then you need to down shift to a lower gear. If you're in the lowest gear and still can't reach max torque rpm then you need to increase pedal assist cadence to reach max torque rpm.

Get a tachometer and a bicycle computer with a cadence meter on it.
 

Urban Fatbiker

Active Member
Joined
Jan 30, 2019
Messages
211
If I’m in lowest gear climbing a hill, and engine rpm is less than mid-range, and starts to lug, my cadence is too fast to bump it up into torque range.

But...now I see my problem. If I match cadence to throttle range...I’ll never be able to start it.
Hmmmm...

I got spoiled with my etrike. 7x3 gearing, and max torque at low RPM, it will climb 30 degrees for a mile at 5mph.
Can’t climb like that on a DF you wobble and fall down 😳
 

Karl Snarl

Well-Known Member
Joined
Sep 20, 2019
Messages
5,691
To be honest hearing SBP is shutting down is breaking my heart.
Me too. This hobby is my thing. I have plans for bikes, and I want the best. I have a SBP shift kit on my "Green Bean" that has been on for years. Never had any problems with it once I got it aligned and tensioned properly. Just changed out the bearing in the crank freewheel after thousands of miles. An after a hundred or so builds of 2t kits in the last half a decade, now I wanted to start on 4 strokers with gears.
 

Karl Snarl

Well-Known Member
Joined
Sep 20, 2019
Messages
5,691
If I’m in lowest gear climbing a hill, and engine rpm is less than mid-range, and starts to lug, my cadence is too fast to bump it up into torque range.

But...now I see my problem. If I match cadence to throttle range...I’ll never be able to start it.
Hmmmm...

I got spoiled with my etrike. 7x3 gearing, and max torque at low RPM, it will climb 30 degrees for a mile at 5mph.
Can’t climb like that on a DF you wobble and fall down 😳
I run the normal SBP kit, to a 44 on the crank, then from a 40 to the back. The back goes 32, 26, 22, 18, 14. I mix up the back cogs sometimes. I just found my go to cog set for the back a few months ago. Turns out they are all vintage cog sets, and becoming rare. lol. I run 24" on that bike. It pulls from a stop, I can creep as slow as I wish. It has a top speed of about 47-48 miles an hour with this set up. I run around 18-30 mph usually. Id I was to do the same setup on a 26" I would use a 48 or 50 tooth for my crank drive cog. An I would go up to a 44-46 on the cog that feeds the rear. It's my trail bike, good for street speed, but also pulls me through all the muddy trails no problems.
 

Sidewinder Jerry

Well-Known Member
Joined
Mar 14, 2011
Messages
3,059
If I’m in lowest gear climbing a hill, and engine rpm is less than mid-range, and starts to lug, my cadence is too fast to bump it up into torque range.

But...now I see my problem. If I match cadence to throttle range...I’ll never be able to start it.
Hmmmm...

I got spoiled with my etrike. 7x3 gearing, and max torque at low RPM, it will climb 30 degrees for a mile at 5mph.
Can’t climb like that on a DF you wobble and fall down 😳

The final setup I had on the LandRider reduction range was 49.21:1 to 18.82:1. In the lowest gear I had to pedal assist on hills that were more than a 20% grade. I had found in the past a 55:1 reduction could get me up 25% grade hills with minimal assist. However, 30% grade hills are common here and require a good bit of assist at a 55:1 reduction.

My engine, a Robin Subaru 35 produces 1.6 hp at 7000 rpm and 1.6 ft/lb of torque at 5000 rpm. Total weight is 350 lbs. Now a bigger engine that produces more torque and a lower total weight won't need as much of a bottom end reduction that I needed.

With the triple chainring shift kit and custom built 7 speed 34-13 freewheel the Sidewinder's reduction range is 66.79:1 to 16.25:1. I can now pull an added 200 lbs up 30% grade hills with very little pedal assist in my lowest gear.

Your situation sounds like the reduction range isn't low enough. Your choices then become put a bigger cog in the back and/or add a second smaller chainring up front. This'll allow you to lower your reduction range without affecting your top end reduction range.


If you don't do these things then you'll have to sacrifice top end speed to get a lower bottom reduction by lowering the input reduction coming into your shift kit. This'll then also lower your top end reduction range
 

Karl Snarl

Well-Known Member
Joined
Sep 20, 2019
Messages
5,691
The final setup I had on the LandRider reduction range was 49.21:1 to 18.82:1. In the lowest gear I had to pedal assist on hills that were more than a 20% grade. I had found in the past a 55:1 reduction could get me up 25% grade hills with minimal assist. However, 30% grade hills are common here and require a good bit of assist at a 55:1 reduction.

My engine, a Robin Subaru 35 produces 1.6 hp at 7000 rpm and 1.6 ft/lb of torque at 5000 rpm. Total weight is 350 lbs. Now a bigger engine that produces more torque and a lower total weight won't need as much of a bottom end reduction that I needed. With the triple chainring shift kit and custom built 7 speed 34-13 freewheel my reduction range is now 66.79:1 to 16.25:1. I can now pull an added 200 lbs up 30% grade hills with very little pedal assist in my lowest gear.

Your situation sounds like the reduction range isn't low enough. Your choices then become put a bigger cog in the back and/or add a second smaller chainring up front.


If you don't do these things then you'll have to sacrifice top end speed to get a lower bottom reduction by lowering the input reduction coming into your shift kit.


Isn't it amazing how it feels when you finally find that perfect combination? Everything everyone wants, starting from stopped, good midrange power, and a nice top speed, and being fuel thrifty. My Green Bean can climb a tree if I wanted her too. Was originally designed to haul my 250lb best friend around in his trailer. I soon found out, he doesn't like his trailer, or the bikes. He's a hang his head out the window of the 4x4 truck and scream at people pig, not much of a two wheeled hog. lol
 
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