higher bike gear for ebike

[lxgoldsmith]

Working on my first ebike. I'm getting a 48V 1000w to go with my homemade 44.4V battery. I won't be done for a while, but I need to know what else I'll need.

Will I need a bigger gear to keep pedaling at 30mph and extend the run?

 

[mateusleo]

I have a 100w 48v bike that easily reaches 55kph on flat, 26' wheels, and it's impossible to pedal at that speed with usual gears. Maybe a 3rd reduction on the middle of the way, adding another chain. Not sure if you can understand what i'm trying to describe, but if you add another reduction, maybe you could pedal at this speed...

 

[wineboyrider]

You'll need a huge Front chain ring like a folder or velo bike would use to make any useful pedaling at WOT even at 44v. I assume you have a yescom kit? There are many calculations that you need to consider, but here is a place to start so you know what gear ratio you need. http://sheldonbrown.com/gears/

 

[teslanv]

If you want to pedal along at 30+ MPH, look into a Schlumf Drive.
http://www.schlumpf.ch/hp/schlumpf/faq.getriebe.engl.htm

 

[100volts+]

If you want to pedal along at 30+ MPH, look into a Schlumf Drive.

Schlumf drives are highly rated but they are costly and are not plug and play but not too difficult to install at least from what I saw on a youtube installation video. From everything I've read they work as advertized.

 

[teslanv]

If you want to pedal along at 30+ MPH, look into a Schlumf Drive.

Schlumf drives are highly rated but they are costly and are not plug and play but not too difficult to install at least from what I saw on a youtube installation video. From everything I've read they work as advertized.

Yeah, the hardest part of the install is chamfering the bottom bracket. Utah Trikes sells and installs them, but you have to ship them your frame.

http://www.utahtrikes.com/ARTICLE-33.html

And they are not cheap. but way cool.

In theory, if you have a Schlumpf HIgh-speed drive with a 44T Chainring, and 14T small rear sprocket, and 26" Diameter wheel, you could attain a speed of 60 mph at a pedal cadence of 100rpm. Changing to an 11T rear sprocket gets you up to 77 MPH. - Although at those speeds, I think I would be hanging on for dear life, rather than trying to pedal the bike faster.

 

[dogman dan]

Get a 7 speed screw on freewheel that has 11 teeth instead of 14. That will help a lot. Then hunt down the largest crank that will fit your bike. For some MTB frames, that will be 48t. But some older frames designed for less fat tires may be able to take a bigger chainring.

 

[lxgoldsmith]

So how do I know what will fit my bike? do I have to take measurements?

 

[dogman dan]

Well, look at your bike now. Is the big chainring nearly touching the frame now? if so yer done. If it looks like you have more space there, if the gear was bigger without rubbing the frame, then you can go bigger.

 

[chvidgov.bc.ca]

It seems that only the DNP freewheel is 11 tooth, which is what most ebikers are forced to accept - not ideal, except for the very rare Shimano MF HG50 11-28(34) which I have two of - I just wore out the 11 toother, so I had to turn it into a 13 toother. The next step up in new Shimano screw-on freewheels is 13 tooth. There are also some legacy freewheels of other types "out there", notably the Sachs 12 tooth, which I also have one of, on a Sachs 3x7 internal/external rear hub on my folder. I think if you went to a new 13 tooth, with a bigger ring, you would get the gearing up decently - if your chain wrap capacity of the derailleurs can handle incremental toothage. Sunrace also makes a decent 13-30 toother. A fatter tire like a Big Apple or Fat Frank will also increase your gearing. Other more exotic solutions like a Schlumpf speed drive (requires frame mod/chamfering) or Patterson freewheel crank (avail. ebikes.ca) are also possibilities, but expensive. I'm running a 60tooth Vuelta chainring on one of my folders, but larger rings often conflict with the chainstay geometry or the folding hinge on folders (hostelleshoppe source). Higher gearing is a perennial issue for ebikers who like to pedal, other than the smaller cassette type motors like the Bafang CSt.

 

[Cephalotus]

The Sunrace MFEX 9AU is a rather high quality 9x freewheel with 11-12-14-16-18-21-24-28-32 tooth.

9x is needed for people that actually want to pedal their e-bike.

Combine that with a crank from a racing bike (i.e. Shimano Sora 52/39) and you should be able to pedal efficiently up to 50-55km/h, depending on your cadence.

 

[lxgoldsmith]

If I pedal faster than the motor, will the bike go faster, or will it top out at the motor's maximum rpm?

rephrased: Will I get force out of the motor when it spins faster than its max rpm?

 

[Cephalotus]

If I pedal faster than the motor, will the bike go faster, or will it top out at the motor's maximum rpm?

rephrased: Will I get force out of the motor when it spins faster than its max rpm?

You will not pedal faster than 40-50kph on the flat without motor assistance. Most people are even unable to pedal faster than 30kph with their ebikes not using motor assist.

At around 50kph your contribution usually will be less than 20%

 

[lxgoldsmith]

Well the point of my asking is to pedal and actually input some force to extend the ride at 30 mph and maybe bump up the speed a little. I want to know that the motor will continue to assist if I could possibly make it go faster

 

[teslanv]

Well the point of my asking is to pedal and actually input some force to extend the ride at 30 mph and maybe bump up the speed a little. I want to know that the motor will continue to assist if I could possibly make it go faster

The motor will continue to assist up to it's unloaded speed, which is based on the winding of the motor and the voltage you are running at.

I have pedaled into the mid 40mph range with an 11T rear sprocket, 48T Chainring and 26" wheels on 10%+ downhill runs. That's about 130 rpm at the crank, which is about as fast as I can pedal.

I have a spreadsheet I can send you to calculate speed based on gearing, if you want to check out a few options. - Just send me a PM and I'll email it to you.

 

[Chalo]

Working on my first ebike. I'm getting a 48V 1000w to go with my homemade 44.4V battery. I won't be done for a while, but I need to know what else I'll need.

Will I need a bigger gear to keep pedaling at 30mph and extend the run?

Unless you are working hard at the pedals, pedaling at 30mph could cost you more drag than it contributes as propulsion. Keep in mind that at 30mph, you have to contribute about 100W at the pedals just to offset the extra drag you incur versus keeping your legs still. Only the pedal power you generate above that amount will help you go faster or extend your range.

If you want to pedal along at 30mph, you'll need a 53 tooth ring to go with the 14t small gear on your freewheel, and you'll have to turn the pedals just over 100rpm.

 

[999zip999]

48T- 11t for 30mph is close to to speed.

 

[dogman dan]

As Chalo pointed out, trying to increase your range by pedaling at 30 mph is pointless. Drag gets so high, that your input might be closer to 1% than 20% at 30 mph. You'll increase your range about one block.

What will increase your range, is pedaling hard on the start ups. So pedal to 20 mph or so, then stop if you will ride 30 mph.

But pedaling at all speeds is good for other reasons, like your health, not having your butt fall asleep, looking like a bike to cops, etc. So gearing so you can keep faux pedaling is a good thing.

When you want more range, slow down, at 20 mph, you can put close to 25% more into it by pedaling, with 48v 14 gearing. Plus drag is so much lower, you get another 25%. You'll increase your range a lot by slowing to 20.

 

[DrkAngel]

Well the point of my asking is to pedal and actually input some force to extend the ride at 30 mph and maybe bump up the speed a little. I want to know that the motor will continue to assist if I could possibly make it go faster

"Near 30mph, a more aerodynamic position outperforms even substantial pedal assist from a "proper" pedal seating position."
See -Motor Output Watts for MPH

 

[MitchJi]

If you want to pedal along at 30+ MPH, look into a Schlumf Drive.
http://www.schlumpf.ch/hp/schlumpf/faq.getriebe.engl.htm

$345 plus shipping here, and he will loan you the installation tool:
http://greyborgusa.com/ats-schlumpf-speed-drive/

I have a spreadsheet I can send you to calculate speed based on gearing, if you want to check out a few options. - Just send me a PM and I'll email it to you.

How is that any better than Sheldon Brown's calculator?:
http://sheldonbrown.com/gears/

 

[teslanv]

If you want to pedal along at 30+ MPH, look into a Schlumf Drive.
http://www.schlumpf.ch/hp/schlumpf/faq.getriebe.engl.htm

$345 plus shipping here, and he will loan you the installation tool:
http://greyborgusa.com/ats-schlumpf-speed-drive/

I have a spreadsheet I can send you to calculate speed based on gearing, if you want to check out a few options. - Just send me a PM and I'll email it to you.

How is that any better than Sheldon Brown's calculator?:
http://sheldonbrown.com/gears/

Technically, it's no better than the Sheldon Brown calculator. I just like that it's an excel doc and you can run various scenarios easily. I would personally much rather manipulate excel formulas to suit my specific needs than have the limited drop-down menus of an online calculator.

 

[lbz5mc12]

Try a longer bottom bracket and I have a 58,48 2 chainring crank set square taper that I'm not using anymore.

 

[dogman dan]

I have a 56 tooth on my big cargo bike, but when you need 1000w or more to go 30 mph, adding a puny human input of 100-150w doesn't gain you much more than a block or two more range.

That's what we are trying to say, you ain't gonna pedal up much more range at 30 mph.

You can gain a lot more range, if you pedal hard on each start up from a stop. But don't believe us, we only have about 10,000 ebike miles each. What would we know about what affects range?

You want range? slow down 2mph and see how that affects it. You'll be amazed.

Once you really slow down, then pedaling can add huge range. If you are riding at 300w, you can pedal up enough to lower that to 150w. And since you just doubled your range simply by lowering wind resistance, the range you get pedaling hard at 15 mph is unbelievable.

The way to add range at 30 mph is to buy it. More battery capacity.

So why did I put a 56 tooth front chainring on my bike if it's so useless? I did it because I can't stand to ride 30-40 miles without pedaling, my ass will die. But if I pedal, I feel better. I may only be flapping my legs, but I still get a health benefit from it. When I need 80 mile range, I ride 15 mph in a much lower gear and I do get more range from my pedaling then.

 

[Punx0r]

On 48V my bike does about 28mph unassisted on level ground. I normally pedal and increase this to 29-30mph and see input power on the wattmeter drop by about 200W. That's on 48-14 tooth gearing with a 26" wheel and 2.25" tyre. Cadence is a bit too fast and sustaining that for several miles is hard work, but good exercise. Much nicer when you have regular downhill sections to coast and quickly rest your legs.

Smaller rear sprockets increase reduction but will wear more rapidly, so bear this in mind if deciding whether to increase the front chainring or decrease the rear sprocket.

 

[Ykick]

Cruising +30 MPH on an overweight hurtling BICYCLE is a FAIL waiting to happen. Some of us do it (for a while) but when you consider how much increased stress you're placing on components that were never intended to be used under those conditions, it's not a wise effort, IMO.

Doubling weight and speed does NOT merely double stress. It's an exponential equation. Every pothole hit or hard brake extract severe toll that's nearly impossible to predict the outcome.

By all means, enjoy an eBike but don't be lured into the trap of trying to make a bicycle do a motorcycle job....