26" wheel vs 20" wheel review

[zombiess]

I haven't seen many people talk about this in my searches, but I haven't searched for it either so I figured I'd just write up my experiences.

The biggest difference is the 26" setup feels very refined and smooth. The 20" setup is a torque monster with instant lots of acceleration. The throttle is very twitchy, even on the 40% setting. I find the full suspension 20" setup is like a sports car and the full suspension 26" bike like a V8 touring car. Bot the setups are running 100V fully charged. 26" setup is a 9c 8x8 and the 20" setup is a 2806. I never thought I'd run the 2806 @ 100V, but now that I am I don't want to go back.

I highly recommend full suspension for high speed bikes, they are worth the hassle for the nicer ride..

 

[SamTexas]

Thanks for the report.

Questions on the 20" bike:
1) Did you change both wheels to 20" or just the wheel with the hub motor?
2) Bicycle or motorcycle tires?
3) What is the top speed on flat ground?

 

[zombiess]

Thanks for the report.

Questions on the 20" bike:
1) Did you change both wheels to 20" or just the wheel with the hub motor?
2) Bicycle or motorcycle tires?
3) What is the top speed on flat ground?

Both are 20" wheels, it's what it came with. I've completely overhauled the bike and now it looks like a bmx but with full susp.
Bicycle tires, no flats yet. I'm running slime tubes and anti puncture strips in the tire.
Top speed is 47 mph, gets to 35mph pretty quick, gonna fix that by upping the amps from 30 to 50

 

[SamTexas]

Can you post a pic of the 20" wheels bike?

 

[zombiess]

Can you post a pic of the 20" wheels bike?

Sure, here you go:

I put the battery setup back on the 26" bike the same way as in this picture. I'm waiting on a handlebar bag to show up for the 20" bike. As long as it fits well and looks decent it will probably be my solution for this bike. Having the weight right over the front wheel should help with the short wheel base and good power.

I have another very similar version of this bike made by Kent and can be had for less than $150 new. I paid $40 for an almost new one, all steel frame.

 

[cwah]

I think for a 20" wheel bike, the best bike is the Dahon Jetstream:

And smaller wheel size doesn't mean slower. Because it consum less power to reach the same speed (you have a better range), so it means that you can just increase the voltage to match higher wheels bike.

I tried on the simulator, here a 26" wheels with 36V8AH (388 WATTS):

==> We have 29kph for 22 km

And here a 16" wheels with 48V6AH (388 WATTS):

==> We have 28 kph for 24 km

So they both use the same power (388 WATTS), they just need a different voltage to achieve approximately the same speed AND the same range.

Any thought?

 

[zombiess]

If you play with the simulator an match speed you will find that most setups using the same motor come out very close (as the graphs show even though the speeds aren't matched exactly) at the exact same speed. The big difference comes when you have hills to climb or want more acceleration, then smaller wheels and higher voltage are king.

That Dahon looks really good, I like it a lot.

 

[pjpeter]

Thanks for this - I've only used a 18" or 20" eBike folders in the past - I took a 26" for a test drive on the weekend and was quite disappointed in the acceleration - it's good to know this is why.

Thanks,
Peter

 

[alban]

That's very helpful, thanks, as I'm thinking of putting together a similar ebike.
Couple of questions:
Do you have a great tendency to do wheelies if you're not careful - particularly on loose ground?
Do you take this off-road and how does it do on rough ground or in mud? Do the pedals seem too low and contact tree roots/ruts etc!?
Do you think a 20" steel folder might be too weak for off-road?
What do people think are the best puncture-resistant tyres for 20" and off-road? Marathon Plus seem a bit too slick and their M+ MTBs are only 26".
Be interested to see if the bars bag is OK for a heavy-ish battery too.
Cheers

 

[SamTexas]

Sure, here you go:

Thanks for the pic. A few more questions:

1) What happens to the chain? Is it there?
2) Is it a frame (and fork) for 26" wheels or is it for 20" wheels?

 

[zombiess]

Sure, here you go:

Thanks for the pic. A few more questions:

1) What happens to the chain? Is it there?
2) Is it a frame (and fork) for 26" wheels or is it for 20" wheels?

Pic was taken before the chain was installed, fully functional now. 48T front 11T rear lets me pedal to about 25mph but I don't pedal this bike a lot. Got the triple chain ring working too (that got me some attention at the bike shop), just in case I decide I want to scale a vertical wall while towing a semi. Evidently when you don't know much about bikes and start building them, you can do things that shops will tell you won't work.

Frame comes setup for 20" wheels, it's a kids mountain bike.

This should be the bike http://www.amazon.com/Kent-Boys-20in-Hyper-Mountain/dp/B003F9RRJA I think Walmart might have them too. You would need to double check that they are still all steel like mine are. I haven't jumped it any higher than about a foot but the frame feels solid and I'm 175lbs. Front fork is of course garbage, but I bought mine used and beat to hell for $20 at a garage sale once I realized it was steel. An dampened adjustable rear shock made it ride much nicer. I think I spent about $400 on parts building it with lower end parts not including the electric stuff, but now I know how to build/repair a bicycle

I'd like to convert a 26" wheel frame to 20" wheels, but often the pedals will be really low. I'm debating going changing wheel sizes on my 26" bike now because of how much more fun the 20" setup is.

I tried upping the amps to 45 on my 26" setup but all it did was make more heat and the motor made some unhappy noises at low RPM and 5400W. I set it back to 33A. I did manage a new top speed of 43.4mph up from 42.X.

 

[miuan]

That wheel build is crazy. I can't imagine you can fit nipples into eyelets at such angles.

 

[zombiess]

That wheel build is crazy. I can't imagine you can fit nipples into eyelets at such angles.

The bike shop that built it said it's at the max. When I dropped everything off I told them it was OK to do a radial build if they couldn't get a cross on them, but the wheel builder managed. It's a single wall rim though. I really should have spent more and got a double wall rim but I was stupid, too late now but haven't had any issues. I have rim tape and an additional layer of duct tape on top of it to protect the tube which I run at 70 PSI. Been good for 100 miles so far. Small + high power = lots of fun!

 

[chroot]

I bet you felt lot jerky steering at high speed on 20" wheel. :lol:

Unless you install extend swing arm as long length wheelbase for the stability at high speed.

 

[zombiess]

I bet you felt lot jerky steering at high speed on 20" wheel. :lol:

Unless you install extend swing arm as long length wheelbase for the stability at high speed.

You would lose that bet surprisingly. I was really concerned about that myself due to the short wheel base, but this bike as stable if not more stable than my 26" bike which has decent rake on it as well. I don't worry letting people ride this at high speed because the steering isn't twitchy at all! It's one of the reasons I recommend this frame for someone who wants to build a small bike. The steering is perfectly fine at 45+mph. Just has good geometry.

 

[wdwrkr51]

Hey, Zombiess;

I've run identical DD motors on a 26 " MTB bike and on a 20" BMX bike, and my experiences are just about identical to yours. For sure, the 20" wheel is more sporty, more responsive and more torquey. The top speeds are only about 2 miles per hour different, due to the greater efficiency of the motor running in the 20 inch wheel By the way I run Maxxis Miracle street ribbed slicks at 90 pound pressure. The handling is razor sharp. I'm sold on the benefits.

You folks oughta try it! You might just like it.

wdwrkr51

 

[Haste]

right on,

i got a super cheap bafang bpm being shipped as i type this. Its very small and light, and in a bmx it would rule. Probly will try 18s with it and see how it holds up first.

Plus a bmx bike is cheap compared to a good name mtb or downhill bike. Can get tons of decent brand names on craigslist for 50 dollars, vs 600 and up for mtb bike.

 

[chroot]

Only difference the 20" wheel will give you a quick acceleration and higher efficiency than in 26" wheel.

 

[Tench]

I am just assembleing a mid mounted HS3540 in a down hill bike running through a freewheel crank, i have removed the second chain ring and front changer to simplify the bike(i wont need very low gearing with a motor to assist) it is running a 44t front and a 7 speed 13-34 rear, with a reduction from the motor to the front chain wheel aswell. calculating the gearing and then relating it to the equivelent wheel size needed to achieve the same gearing with a DD setup so i could do comparisons on the simulator would be low gear 9.43" wheel and high gear 25.6" dia wheel, this should give me the advantages of both a small and large wheel setup. cant wait to get it finished. It will be running a 40A controller on 18s 16ah lipo. The max range i could achieve on the simulator comes from running WOT in low gear, slower but more efficient. It will also have monster torque at low speeds without using loads of Amps and creating a lot of heat.
It does seem to me that the hub motors are more efficient and livelier to ride in a smaller wheel, but ride quality on a rough surface is improved with a larger wheel, hopefully i will have the best of both worlds.

Simon.

 

[joe tomten]

zombi,

I have a bmx with a cheapie front shock where I've bolted the batteries to the bmx handlebars. Works good with the weight over the front wheel, especially in the snow when I'm riding with studs, rear hub drive.

I'd rather the battery be mounted lower and fixed to the frame, instead of waiving around on the handlebars so much. Not so much that it affects handling while riding, but that it is a pain when leaning it up when resting. Now i'm in the habit of just bungying up the front brake and it stay put.

So that kent full suspension bmx you have, do think it would do ok as a platform for cutting up and making a longtail? Sort of a shortish longtail with fully suspended. A FS microlongtail for lack of a better term. I'm looking to do some frame bashing and finding anything on craigsslist that is steel and full suspension has been hopeless.

thanks,
Joe