20" wheels

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Legwon

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Mar 2, 2013
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i now that some ppl have done this. put an engine on 20" wheel bike.
am thinking about doing this for my second build.

what should i look out for?
ex. 50t pocket on 26" wheel is equivalent to what on a 20"?
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
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a 50t would probably do burn-outs on a 20" wheel, and only go 15mph.

the smaller the wheel, the less power it takes to get rolling.

ultimately, top speed suffers compared to a 26" bike. it's just simple physics.

i've got a 20" race bike that's competitive against the big guys.

it's built around a 26" frame, though.

the wheels i used are 16" moped wheels, which are the same as 20" bike wheels. that means you can use a 16" moped or motorcycle tire on a 20" bicycle wheel.

i use pirelli ml75's on mine.
 

Legwon

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Mar 2, 2013
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not looking for speed or competition... just want a Kool little cruiser for about 20-30KPH, if i get more great :)
 
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maurtis

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Dec 14, 2011
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Kyle, TX
Whoa, those Pirellis are nice! If I put more work into my 20" ebike, I might just switch to those from the stock 2.4" knobbies! The extra height for a little more top end would be nice.
 

bairdco

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Aug 18, 2009
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yeah, the pirelli's are awesome. and they were only 16 bucks each.

and they're about 100 times more flat resistant than a bicycle tire, as well as being dot rated for 64mph.

they're pretty freakin heavy, though.
 

bairdco

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Aug 18, 2009
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you can find 16" moped wheels on ebay for pretty cheap.

the hubs are a lot wider and the axles are thicker, but the sprocket's mounted to it. i'm running a 35t and with a modified 66cc it tops out at 43mph.
 

bairdco

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Aug 18, 2009
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i'd go for the 36. the 20" will take off much faster than a 26 because it takes a lot less effort to get rolling.

i'm assuming you're not a big guy (since you're building a smaller bike) so a 36 should pull you around pretty good.

if the motor is gonna stay basically stock, you'll probably top out around 30mph, maybe a little more.

if you go 44, the motor's gonna rev out like crazy and probably do 20mph.

my 20" racer has a 32 and still keeps up with the big bikes. but the engine's been worked over pretty good.
 

Legwon

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Mar 2, 2013
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Van bc Canada
i'd go for the 36. the 20" will take off much faster than a 26 because it takes a lot less effort to get rolling.
....{snip}...
if the motor is gonna stay basically stock, you'll probably top out around 30mph, maybe a little more.

if you go 44, the motor's gonna rev out like crazy and probably do 20mph.
ok thx thats what i was looking for.

i'm assuming you're not a big guy (since you're building a smaller bike) so a 36 should pull you around pretty good.
im not a monster by any means lol
im 5'9" 180lbs ..

but what ur saying about the speed of the sprockets sounds about what im looking for. nothing super fast. but a good cruiser.
 

577-Jersey

New Member
Mar 23, 2013
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central western nj
At least a 36 tooth,,may want to go up a few teeth in the front as well bro..,,Im no scientist but 6"makes a huge difference,,your gonna get tired of cruising around at pedal speed after a while...lol.
 

Legwon

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Mar 2, 2013
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Van bc Canada
At least a 36 tooth,,may want to go up a few teeth in the front as well bro..,,Im no scientist but 6"makes a huge difference,,your gonna get tired of cruising around at pedal speed after a while...lol.
i know that the wheel size is gonna change the speeds drastically, just wasnt sure by how much. thats Y i asked about it.
im not gonna worry about goin too slow or fast on the 20inch wheels. its not gonna be a long haul rider. thats what my 26incher is for.
20-30mph is probly MORE than enough.
 

577-Jersey

New Member
Mar 23, 2013
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central western nj
Lemme know how you make out,,
I plan on building a 20"one of these days also,,maybe you can take some of the guess work out for me,,I would like to cruise 20-25 mph also,,30 mph on a 20"is flyin!! :)
 

maurtis

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Dec 14, 2011
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Kyle, TX
Question about the 16" motorcycle tires (like the Pirelli ML75) on a 20" bicycle rim, I assume you are running a tube with those. How hard is it to mount onto the bicycle rim. Is it the sort of thing I can "easily" do in my garage with hand tools like a regular bicycle tire, or do I need to take it to a shop?

I assume the carcass is a lot stiffer.
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
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they are a lot stiffer, but you should be able to do it yourself. i didn't have a problem.

they are tube type tires. i have the heavy duty moped tubes with metal stems.

you could probably use bike tubes, but the moped ones are pretty cheap, too.