Pedaling and speed

[eehlert]

Before I go out and buy a hub motor, I'm trying to make sure of something. I'm planning on pedaling the whole time I'm on the bike, hoping that the motor will a)make pedaling easier; b)allow for a higher average speed. Ideally, I would like to keep speeds over 25mph in most sections of the ride. From reading previous posts, it sounds like if the human-unassisted speed of the hub motor/battery is 20mph, if I try to increase the speed to 25 mph by pedaling I won't get ANY help from the motor/battery. The alternative possibility (B) is that I can get to 25mph with x% less effort than I would on a motorless system. That's my preference, of course.

Which is it? If (B) is the case, I could probably get away with all-in one kit system. If the former is the case, I'm probably looking at something "custom" using different parts from the ebikes.ca site.

 

[Lowell]

If you want to go 25mph, pick a motor/battery combo that will give decent power at that speed.

What wind and voltage were you considering?

 

[TylerDurden]

... it sounds like if the human-unassisted speed of the hub motor/battery is 20mph, if I try to increase the speed to 25 mph by pedaling I won't get ANY help from the motor/battery.

It would be the case if the no-load speed of the system is only 20mph...
but if the top speed on the street with rider is 20mph, you could share the load with the system and reach 25mph by contributing just 25% more energy.

 

[Ypedal]

A " custom " solution is not that complicated.

1-Do you already have a bike to convert ?

1.5 - If you do, What bike do you have?

2- How much do you weigh and how far do you realistically want to travel?

3- What's your budget

 

[sabrewalt]

To assist at 25mph won't he have to change his gearing at least on an MTB?

When I get much above 21mph, I can no longer "feel the bike" in my pedels. OF course that only happens on long downhill runs. My unassist speed on flats is 19mph.

Except for downhills I pedel the whole way and compared to an unassisted bike, I look like I am in Fabulous condition because I am going up long inclines at 18-19 mph instead of 8 or 9 mph.

 

[The7]

From reading previous posts, it sounds like if the human-unassisted speed of the hub motor/battery is 20mph, if I try to increase the speed to 25 mph by pedaling I won't get ANY help from the motor/battery.

Unfornately, this is an legal requirement for PAB (power assisted bicycle) in most places of NA.

 

[Ypedal]

Depends on the bike.

My BMX gearing sucks at anything above 10 mph... but on my 26" MTB i can pedal along above 25 mph with a large chainring. If using 700C wheels then it gets even faster !! !knightmb !!

 

[xyster]

Unless the system is electronically restricted to 20mph, even if the top speed on the road is 20mph, you'll get some assist above that speed -- but only to the point of the motor's no-load speed. It won't be much assist though.
My over-volted Currie has a top speed of about 24mph. If I pedal pretty hard (at a pace I could keep up for about 1/2 mile), I can get it up to 26 or 27mph for that 1/2 mile I'm pedaling hard.

 

[patrick_mahoney]

I would think that the bike motor would need to be a bit faster to provide much help at 25mph.

On my mountain bike, first as was pointed out, I had to change the gearing. I changed the gears to a road bike set of gears. I bought the gears on Ebay for something less than $15 shipped, and my local bike shop installed it (I couldn't figure it out) for another $10. This gear set gives me the ability to pedal at a decent cadence at ~30mph.

On my bike, if I hit max throttle and don't pedal, I go 28mph.
If I hit max throttle and pedal lightly, I go 29mph.
If I hit max throttle and pedal moderately, I go 30mph.
And if I hit max throttle and pedal like a madman, I go about 33mph.

Somewhere around 32mph, my motor seems to not be helping very much. There might be something there, but if there is, it's not much. I get the impression that to get above 32mph, I am doing most - if not nearly all - of the work. Most of the time, when I'm riding to work, I see the GPS speedometer read something like 29.7mph.

 

[The7]

I would think that the bike motor would need to be a bit faster to provide much help at 25mph.

On my mountain bike, first as was pointed out, I had to change the gearing. I changed the gears to a road bike set of gears. I bought the gears on Ebay for something less than $15 shipped, and my local bike shop installed it (I couldn't figure it out) for another $10. This gear set gives me the ability to pedal at a decent cadence at ~30mph.

On my bike, if I hit max throttle and don't pedal, I go 28mph.
If I hit max throttle and pedal lightly, I go 29mph.
If I hit max throttle and pedal moderately, I go 30mph.
And if I hit max throttle and pedal like a madman, I go about 33mph.

Somewhere around 32mph, my motor seems to not be helping very much. There might be something there, but if there is, it's not much. I get the impression that to get above 32mph, I am doing most - if not nearly all - of the work. Most of the time, when I'm riding to work, I see the GPS speedometer read something like 29.7mph.

What is the no-load speed of your ebike (when the drive wheel is off groud)?

 

[eehlert]

This has been helpful, sort of. To provide more information on me/my bike.

I have a bike. It's an ancient diamondback w/ no suspension. I've got 3 gears in front and 8 in back. What is that, a 24 speed? Rims are 26" x 1.5-1.75. I took off the MTB tires and now have kevlar slicks. I've never clocked myself but in highest gear I'm pretty sure I'm doing over 20MPH with a low cadence. I'm going to get a rear wheel hub motor w/ wheel (because the rear wheel has some broken spokes anyway. I weigh 240 which I hope to reduce some by biking to work. Distance to work is approximately 12 miles - I doubt I'll use the bike for longer trips than that. Grade is gradually uphill all the way. Only in one place is the grade steep, and I don't mind supplying most of the power by pedaling up that. I'll charge the batteries at the office before going home, but because I'm going downhill all the way, I won't need the motor as much anyway.
Cost is not a big factor. I'm guessing that I could be close to $1000 with Li-ion/Li-ion Phosphate batteries if I can get them - obviously I'm not spending anything on the bike itself. I don't want regenerative capabilities.

Based on prior threads, I was considering a C-lyte 406 w/ 48v battery; none of the all in one kits I've seen come with batteries that strong. I'd love to get a system that performs like Patrick's but can't make my own battery bank.

Sounds like while I'm shopping I will have to assertain the no-load speed of the "system" (which I assume is the combination of motor-controller-battery). Perhaps one of you or Patrick would like to help me shop. He lives "in the area".