Cassettes, Freewheels, and 20 inch e-Bikes

dartagnon54

New Member
Excuse me if this has been asked before. I did do a search here an found nothing related. My question revolves around the fact that most freewheels used for multi-speed 20 inch folders on e-bikes were not designed for such small wheels. A 20 inch wheel with a 2 inch tire has 20% less circumference than a 26 inch wheel with similar tires, which leads to the difference in top speeds at similar cadence.

I have a 20 inch single speed folding Prodeco Mariner (2011 version- throttle only, no PAS). I find that when riding with other cyclists on full size bikes, electric or not, I have a difficult time keeping up with them without using the throttle, due to the gearing. I am not tired at all, it is just that it requires a sustained cadence of over 60-70 cpm, which leaves me feeling like a hamster on a wheel. I have a 48T chainring and a 14T cog. I am looking to get a multi-speed folding 20" e-bike, but everything but the top tiers seems to use a freewheel rather than a cassette, and most come with a 14T smallest cog, and chainrings between 48T-52T, thus I would expect a similar issue to what I see now. There are very few freewheel options that use a cog smaller than 14T. Cassettes on the other hand, often go down to as small as an 11T cog.

Has anyone here found an affordable multi-speed 20 inch folding ebike that either uses cassettes or already comes with a more appropriate smaller cog?

Thanks!

Dave
 

harryS

Well-Known Member
DNP 34T-11T freewheel. About $30-35. I've installed them on our e-folders. Since the Prodeco is front drive, a freewheel replacement ought to be easy. You'll also need the Parke tool to remove the old one, under $10,

Edit. Call it $40. I got ours for under $30 a few years ago. And it's not just 20" bikes that could benefit, My 26" e-bike is 34-14 and it's geared too low if I wanted to pedal at 25mph. Good thing I don't want to do that.

 

dartagnon54

New Member
Harrys - Thanks for your reply. I was aware of the DNP, but have seen some mixed reviews on them for durability. This would be for my next purchase, a 20 inch multi-speed folder. No options for that for my current 1-speed other than perhaps a Sturmey Archer 2 speed kick shifter internal hub. It has the 110mm OLD that I need for the current bike.

When you use the DNP do you need to make any modification to work with a Shimano shifter and derailleur for indexing?

I am close to ordering a Voltbike Urban. Looking at all similar options going into the Xmas shopping season.

Regards,

Dave
 

harryS

Well-Known Member
Yep. You read the reviews from hard core bikers, it sounds like a piece of junk, but it's the only game in town. We've put several thousand miles on ours, but we're not pounding the pedals at 25 mph either, so they hold up. I didn't do anything with the chain. Kept them at same length. Replace 7 speed with 7 speed, so the derailleur limit screws were not touched.

Our motors used the standard Bafang 9 pin male connector , which fits thru the axle nuts, so the motor cable easily goes thru the Park FR1.3 free wheel tool. Other motors, you may not be so happy.

42499 42500
 

AHicks

Well-Known Member
Rad has been using the 11 tooth DNP for it's production bikes for a year now, and I haven't heard anything in the way of complaints that entire time.

Knowing that, and experienceing a couple of them first hand now, I would question the validity of that critical review.
 

harryS

Well-Known Member
DNP hate is seen on bike forums, not ebike forums, mostly from the people that stretch out chains every six months and replace cassettes annually. A DNP wouldn't last six weeks with these guys, even if you paid them to use a freewheel.

Nonetheless, their feedback is based on facts. It's like comparing a Honda SUV to a Jeep. The Honda is nice, comfy, and does the job for most people, but take it out in back country, it hasn't got the ground clearance and will break. A cassette with 11T is stronger than a freewheel with 11T, and I think Shimano makes a better quality freewheel than DNP.
 
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AHicks

Well-Known Member
OK, so I would question the validity of that review when the 11 tooth DNP freewheel is used on an e-bike!
 

rich c

Well-Known Member
I thought changing the front chain ring was the best way to make a major change. Changing the cassette will only make a minor difference.
 

dartagnon54

New Member
I thought changing the front chain ring was the best way to make a major change. Changing the cassette will only make a minor difference.
I use the Speed at Cadence calculator at BikeCalc.com, and it shows the interdependence of the variables, including also tire and wheel size.
 

harryS

Well-Known Member
I thought changing the front chain ring was the best way to make a major change. Changing the cassette will only make a minor difference.
Depends where you started.

14T to 11T is 21%. is freewheel/cassette
40T to 52T is 39% on front chain

But if your front chain is already at 48T, then
48T to 52T is 8 %
 

AHicks

Well-Known Member
I thought changing the front chain ring was the best way to make a major change. Changing the cassette will only make a minor difference.
Not sure if there is a "best"? Sometimes you don't need a lot. When I started, I could barely maintain a 15 mph cadence. With the 11t change, 20 mph is not an issue. As I rarely ever venture over about 15mph while under power, that change was just right here!
 

DIY-Guy

New Member
I have a Magnum 20" folding bike with a very narrow mechanical gear range (14-28). The table attached shows the calculated speeds for different cadences with the lowest and highest gears for this bike, a conventional 20" folding bike, two similar fat tire 20" e-bikes and a hybrid road bike. I can maintain a comfortable cadence of about 60 rpm. So top speed without the battery is limited to about 13 mph for me. I plan to change out the cassette to an Acera Shimano CS-HG41-7 (~$18 from Amazon, 11 - 28 t). That would make a 60 rpm cadence give about 17 mph-- less than the 4" fat tire bikes since the wheel circumference is smaller.
 

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goldconch

New Member
I regret I too am only pretending to be pedaling for appearances sake while under full throttle most of the time in 14t (Shimano MF-TZ500-7) on QS Dolphin. I've been fully seduced by the magic of full throttle. Alas, it would be more stable and self-affirming if I could genuinely participate a little with an 11t cassette gear. Going to order the CS-HG41-7 and hopefully the 21% improvement will help bridge the performance gap!