Hello

[ACJ1]

I would remove that rear fender, and at least ad a seat. I had a gas scooter and it was scetchy at 25mph. A seat makes it much more manageable. If you use a 3spd IGH you will need a jackshaft to convert the power to the normal pedal side

I agree about the seat and the rear mudguard (fender) removal. The geometry is tricky enough without the mudguard standing the engine off even further. I think the engine needs to be about the 1 o'clock position, slightly forward of rear wheel centre. As I've said below, the handle bar position is pulling the rider forward as well. I may just reverse the stem and have the bars behind the steering tube, but that may be considered dangerous from a steering dynamics POV - the stem could be shorter and still retain the bars on the front side. Some details to sort, including a bigger kick board to stand on (5 bar check plate?), and maybe some foot bars to eek the feet as far forward as possible to nearer the front wheel. Certainly, a generous seat height may be required to fit a rider in comfortably.

 

[Sidewinder Jerry]

Thank you. I'm in UK unfortunately, ...regarding the staton gearbox - it looks a nice thing. How do you find the 1st gear performance with the 3spd hub - Does it pull from 0mph with the centrifugal clutch? I'm slightly loathe to lose 10mph at the top end when the power is there, and although I will do detailed ratio calcs, the staton feels like slightly too much ratio. This attached photo is the 'other gearbox' that is available to me and relatively cheap at £35. It's 5:1 and achieves the correct rotation I believe on the IGH sprocket side. With a slightly smaller drive sprocket (swap off the 3:1 I already have?) and again a largish sprocket on the IGH free wheel I can keep it all in T8f chain and keep a higher top end. I know speed isn't everything, but I agree with GW's comment about the seat, an' all - the geometry isn't quite right at the moment. The rider has to lean towards the handle bars - they need to come backwards.

After doing some research, the max rpm for the TomKing is 8000. The max hp is at 7000. The max torque is at 5000. Which these engines neither have a lot of hp or torque. Meaning 35 mph on level ground isn't going happen, unless the rider and bike weighs less than a 175 lbs. At 35 mph and while standing you'll be very prone to feeling death wobbles going on under you.

As you can see with with a higher rpm engine you're going to need more reduction than a 5\1 transmission system. A 28t sprocket is the largest one you can put on a 3 speed IGH. So even if you put something as small as a 9t sprocket on the transmission that's still only a 15.56\1 reduction. When ran through a 3 speed IGH you'd have the following reductions.

1) 20.74\1
2) 15.56\1
3) 11.67\1

2nd and 3rd would be useless on level ground. You'll actually burn up the clutch in 3rd on level ground.

With the suggestion I made


1) 29.69\1
2) 22.27\1
3) 16.7\1

This way you should also be able to make it up some small % grade hills as well.

 

[ACJ1]

After doing some research, the max rpm for the TomKing is 8000. The max hp is at 7000. The max torque is at 5000. Which these engines neither have a lot of hp or torque. Meaning 35 mph on level ground isn't going happen, unless the rider and bike weighs less than a 175 lbs. At 35 mph and while standing you'll be very prone to feeling death wobbles going on under you.

As you can see with with a higher rpm engine you're going to need more reduction than a 5\1 transmission system. A 28t sprocket is the largest one you can put on a 3 speed IGH. So even if you put something as small as a 9t sprocket on the transmission that's still only a 15.56\1 reduction. When ran through a 3 speed IGH you'd have the following reductions.

1) 20.74\1
2) 15.56\1
3) 11.67\1

2nd and 3rd would be useless on level ground. You'll actually burn up the clutch in 3rd on level ground.

With the suggestion I made


1) 29.69\1
2) 22.27\1
3) 16.7\1

This way you should also be able to make it up some small % grade hills as well.

This project isn't going quick, but I'm getting more thoughts about it, doing fag packet calcs here and there; mainly investigating top end (speed/power) performance and low end (gradient/torque) sensible numbers to figure out ratio requirements and optimal percentages.
I agree about the engine not being brimming with power or torque, and that is half the fun I think, figuring out the optimal usage.
I did run some numbers through the bicycle power calculator (link at bottom), and it takes about 700watts to maintain 30mph, so that should be achievable once losses are in the mix.

I also did come gradient calcs, for a 15% (1 in 5) slope and 120kg and worked out roughly that about overall approximate 48:1 ratio (for a 20" back wheel) is required to generate the torque to maintain the force required to climb that slope. Granted, that climbing has to be at a minimum speed of about 6 mph, so the centrifugal clutch is fully engaged, so I can see problems with even operating at slow speed, i.e. getting going on an incline.

What all that means is that a 3 speed Hub doesn't really have the ratio spread to achieve the low end torque/speed requirements and the high end power usage. 3 speed hubs are typically about 180% and this problem really needs 300% or more.

Hence I found the attached Halfords (a UK bike shop) Carrera at sensible money and bought it, with a nexus 8 speed Hub. The only issue is that the bike is quite tidy and my wife doesn't want me butchering it. So the hunt for a hub or working out some configuration of hubs (maybe 2 X cheap 3 speed sturmeys can be used in-line?) to get the ratio spread, continues. I quite like the Enviolo CVT hubs but not sure if their efficiency wouldn't compromise the top end speed. They don't quote efficiency numbers. Or get a nexus hub and shifter off AliExpress, or something.

Thank you for reading, and thoughts.
. https://www.omnicalculator.com/sports/cycling-wattage?calculatorResult=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

 

[Sidewinder Jerry]

On my bike I have a Staton Inc 18.75\1 reduction gearbox. This goes to a Staton Inc triple chain ring shift kit which then powers a 7 speed 34-13 freewheel. The reduction range is 66.79\1 to 16.25\1.

I then designed a 1 handed color coded system to where I had 9 sequential non-reduntant gearing ratios. The only time a front chain ring is shifted is when in either rear sprockets (3) or (5).

Starting Gears:
1(1) Red
Starts for going up steep hills or when pulling a heavy load.

2(3) Yellow
All other starts.


Red Gears
1(1-3)
Steep hill climbing; heavy load pulling gears

Yellow Gears
2(3-5)
Around town general use gears.

Green Gears
3(5-7)
Open road use gears

Notice with my shifting system how the bicycle chain stays in a fairly straight line. There isn't any cross chaining like you see on a single chain ring shift kit.

 

[Sidewinder Jerry]

Your wife is correct in you not running engine power through an 8 speed IGH. The more gears an IGH has the smaller the parts are inside of it; thus the less torque it can handle going through it. There's been those in the past who've ran engine power through an 8 speed IGH's only to quickly discover they destroyed an expensive IGH. I never recommend running engine power through anything more than a 5 speed IGH.

Then you're going to need to develop a sequential non-reduntant shifting system.

 

[cloakedvillain]

Why not use that bike? You could easily do a friction drive with that motor and have a gentle helper style of build. Not aure how the shipping works out internationally but a staton friction kit is about 110 usd right now with a fair shipping cost domestically.

Staton Inc

.930" Drive Roller. 76 mm Clutch Rotor / 78 mm Clutch Drum / clutch bell. Friction Drive, Rear or Front Mount Kit. No Engine or Kill switch. If you want a front mount kit for a trike be sure and click on the front mount kit. You may want to add the 6 Hole bracket Kit for wheels up to 28" or...

www.staton-inc.com

Not sure if it would be cost effective but you could drive the front wheel, mounting the engine on a rack.

Swap the front wheel for a disc brake wheel and mount a china doll sprocket to it. Install a rim brake because just a rear roller brake wont cut it. There are options anywhere from 28 to 60 in 415 chain teeth that mount to the iso disc brake spacing.

Assuming you stick with the 5:1 primary that gives you a wide range of options, but it would only be single speed.

 

[cloakedvillain]

Sticking with the front wheel drive idea, according to the sheldonbrown website some fat bike front wheels have a 135 old spacing meaning you could run an internal hub up front if your bike has a matching steerer tube for a fat bike front fork with the 135 spacing. Not sure how well the dropouts match because most internal hubs have flat axles or square washers to stop counter rotation of the hub.

 

[darwin]

Looks like an airplane cockpit, what's on the other side. Pic please.

 

[Sidewinder Jerry]

View attachment 214099 Looks like an airplane cockpit, what's on the other side. Pic please.

I'm not really sure how standard operating equipment (gear shifters, directional light controller, loud horn, brake lever) constitutes being as complicated as an airplane cockpit????

The OP is wanting a wide range reduction system to enable his small engine to be of practical use. Without getting off subject and going down rabbit holes. The only thing on my right handlebar, which would be useful for when shifting should occur is a tachometer.

 

[cloakedvillain]

You haven't seen airplane cockpit. You could have engine rpm, rider cadence, rider torque, rider power and engine power. Fuel level gauge, inclinometer, speedometer, odometer, gps. Barometer, thermometer, compass.