22" (451mm) and/or 20" (406mm) rims + 16" motorcycle tires

auraslip

10 MW
Joined
Mar 5, 2010
Messages
3,535
As in a wheel between the standard 24" wheel, and the 20" wheel. For those of us trying to cram as many batteries as possible in frames that are often to large for the rider, this size could be very useful. In my case 24" wheels leave me tiptoing at stop lights, but 20" wheels would risk pedal strikes on sharp turns.

Traditional Designation______ISO Bead Seat Diameter
26 x 1.00- x 2.125_____________559 mm Most Mountain bikes, cruisers
24 x 1.5- x 2.125______________507 mm Juvenile mountain bikes, BMX Cruisers
20 x 1 1/8; x 1 1/4; x 1 3/8____ 451 mm Juvenile lightweights, BMX for light riders, some recumbents
20 x 1.5- x 2.125______________406 mm Most BMX, juvenile, folders, trailers, some recumbents

http://www.sheldonbrown.com/rim-sizing.html

The problem is the inconsistency in the "Traditional Designation". I move from here on out we go by the ISO Bead Seat Diameter.

The next question is sourcing suitable tires and rims for high speed ebike applications in the 451mm size. Of course they don't exist, but since I saw 22" tubes and spent an hour searching for 22" bike rims, I thought I'd save others the time.
 
In an attempt to bridge the gap....20" bmx rims with 16" motorcycle tires seem to give an overall diameter of what a 22" bike rim and 22" hookworms WOULD give.

Can anyone recommend matching 20" rims and 16" motorcycle tires that work?
 
Auraslip, I got hooked on smaller rim sizes as a solution for my uber-tall “medium” frame a few months ago ~ although gave up on 21, 22, and 23-inch rims. I looked and looked, built up a load of information, and even made a reference guide - Rims and Tires Reference

After weeks of searching, I became completely frustrated trying to source a 20-inch bike / 16-inch motorcycle tire due to the lack of options in the United States. :cry:

As it turned out – I bought the Kris Holm 24-inch Unicycle Rim and went with the phatty Maxxis Hookworm tires. Can’t tell you how they’ve worked out though… I’m still Doing the Math on the motor. :oops: :)

...and now you know the rest of the story, KF
 
21'S AND 22'S are around but hard to get i've only found them on really old dragsters and lady's bikes

but if your looking for some look towards wheelchairs where their a bit more common and plyable solids are available to
 
Yeah that’s what I found too: Vintage 60’s Italian and Japanese motorcycles had 21- or 22-inch rims. Looked kinda neat and collectable too.

But you know…

<Cue spaghetti western Spanish guitar & whistlin’ solo >

When yer heading off through the desert and you get a breakdown, you sort of want something in a part that it commonly found to get you on yer way again without having to put up with a lot of hassle. Trust me: I know first-hand what it’s like… in the desert… a l o n e… with a Honda drive chain shattered into 5 worthless pieces… at the edge of Death Valley… near sunset.

<Cue rattlesnake rattlin’>

When you see one car go by per hour – the first one manages to get away. The second one though… I forced to stop. Some memories never fade.

<Pan to headstone, Cue Mission Bell gong…>

That’s why I gave up on the obscure and went with something more mainstream. It’s the same way in engineering: Don’t sole-source parts or you’ll get screwed. I don’t understand the reason why there isn’t a 22-inch option, but durn-it that’s what it is! Just seems kinda silly, even conspiratorial, and downright Republican!

<Cue tumbleweed rollin’ by>

But if you happen to rustle-up a good supplier lemme know and I’ll add it to the Reference.

Chapped, & thirsty. KF
 
Sun Alloy Rim 20 x 1-3/8 CR18 http://www.amazon.com/Sun-Alloy-CR18-Silver-Satin/dp/B000AO7EX2

SunRingle Sun ICI-1 20x1-1/8 http://www.amazon.com/SunRingle-Sun-ICI-1-20x1-1-presta/dp/B001ACF2D2

A couple different tires can be had....http://www.treefortbikes.com/product/333222368373/546/Intense-Micro-Knobby-Folding.html

Small tires though... might be good for a FS build
 
Not much to add really other than to say funny post Kingfish
and perhaps pm Johnrobholmes for 20in rims 16in tires he seems to find them
ok in the USofA, he's in some feared midwest moped gang they likely have the distributorship of
these hard sort after rim/tire combos :mrgreen:

KiM
 
AussieJester said:
Not much to add really other than to say funny post Kingfish
and perhaps pm Johnrobholmes for 20in rims 16in tires he seems to find them
ok in the USofA, he's in some feared midwest moped gang they likely have the distributorship of
these hard sort after rim/tire combos :mrgreen:

KiM

Funny: hehe – thanks AJ! It gets a little slow around here and sometimes I just get unbridled…

On Johnrobholmes: That would be awesome because the selection sucks here. There are a good many choices in the EU but we can't get diddily unless you like Pirelli or Kenda. Michelin and Continental have some great treads - but it's like I said - a conspiracy to keeps these choices outta here. I even called the US Distributors and it was the same sad story; not available.

The other problem is sourcing a tire that’s less than 3-inches wide because most bike frames can’t take it; 2.75-inch is about the maximum (some exceptions apply).

The other thing that bothered me is that bicycle tires cannot handle high-speed; I have an out-of-round wobble above 30 mph that grows more profound at higher speed; balancing the rim wouldn’t help: Had a regional Tire Center look at it and they flat out said it’s the tire that’s out of round and not the rim. Only way to get past that is the DOT rating and we’re back to 20-inches with limited choices. At least the Maxxis is a well-constructed tire, though the rubber is softer than a Specialized Armadillo; the latter ain’t worth a damn in the cold rain here because it turns hard and slips. I am literally building a new bike bag to move the weight forward from the rear just for that reason.

Given the limited choices I finally decided the 20-inch would have been too small and it would look ridiculous on my frame. If I had thought this through, if I knew what I know now back then – I would have built a light motorcycle and had vastly better selection. There will be a Next Time.

BTW – if you look closely, the 26-inch Maxxis Hookworm is 3-full inches taller than the 24-inch; I have both. That’s how this hunt all started: Receiving that tall 26-inch tire and discovering the medium frame was extra-tall. It would take me a step-stool to climb that electric beast. Sheesh!

I just wanna get down the road and have some fun.

Oh, and for the record… I broke down twice coming and going through Death Valley. First time was the chain, the second time the left piston. It sucked; no parts available even in Las Vegas. First time I got towed back to Beatty and slept in the backseat of an old Chevy; a machinist fabricated me a chain by combining two short lengths scavenged from heaps lying about. The second time I ran on the remaining cylinder into the next “town” with oil flowing out the left exhaust. Did you know there’s an Opera House (or was) at Death Valley Junction? I first read about it in National Geographic. Well – I got to see it up close and personal cuz that’s where the bike gave up the ghost. Had to wire for money to get home. Left the bike there in the custody of one “Bearded George”. I ended up sending him the pink slip; with too few parts available it was too much of a hassle to retrieve. Then I joined the Navy. 18 months later I get this Christmas card from Bearded George; it said: “Thanks a lot for the bike! I finally got it working. Merry Christmas.” Glad someone got some use outta of it. I bet he had access to a machine shop.

The Fat Lady sang. KF
 
I like that story =)

BTW – if you look closely, the 26-inch Maxxis Hookworm is 3-full inches taller than the 24-inch; I have both.

I just measured my 24" and 26" cst cyclops (same thing as a hookworm), and they were ~25" and ~27" tall respectively. Although I run them at low psi and getting a measurement with the wheel's on the bike was a pain.

So you didn't ever get the 16" motorcycle tires on the 406mm rims?

Here is the final update on 20 inch rims(406mm) and various tires for determining overall diameter of a particular mounted tire. These are mounted on Alex DX32 rims, but that really makes little difference in the final number.
1. Perelli ML7501 overall diameter is 21.375 inches (543mm)
2. Innova 20x2.125 (IA-2047) overall diameter is 20.00 inches (508mm)
3. innova 20x3.00 (IA-2018) overall diameter is 21.625 inches (549mm)

That is only 3.625" shorter than a 24" hookworm. And since the radius of the wheel is what effects stand over height, it would only lower it by half.

So a 20"(406mm) rim with 16" pirelli ml7501 will lower stand over height by

:arrow: 2.8" from a 26" wheel with hookworms
:arrow: 1.8" from a 24" wheel with hookworms

I can see other benefits besides lower stand over height:

:arrow: Tire clearance. Most chain stays and forks get wider the closer to the axle. This would make it easier to fit larger tires.
:arrow: Comfort and safety. It's said fat tires provide 1" of air suspension. Motorcycle tires would provide even MORE.
:arrow: Tire clearance. More clearance on the down tube to mount stuff. More clearance on the seat tube to mount stuff. Controllers, and battery boxes go great there. Also FENDER clearance!
:arrow: DOT approved for speed.
:arrow: Cheap super thick tubes!

Some disadvantages:

:arrow: Possible pedal strike on turns.
:arrow: Greater unsprung and rotational weight.
:arrow: Small gearing means it will be harder to pedal at speed.
:arrow: The debate is out on top speed. My 26" 9c 2806 is the same speed as my 24" 9c. It's supposed to be slower, but higher RPMs mean greater efficiency.
:arrow: COST. The wheels will have to be custom built. Unless you can source 406mm disc wheels.

Since we have the Pirelli tires picked out, the next step is finding a suitable wheel or at least a rim to build on to a hub.
 
Story: Ha! I’m full of it. Stories, & stuff. :D

Some feedback.
I just was not satisfied with the USA selection; the only other thing I could find available were unknown Chinese tires and I didn’t want to go there. Since my rear frame couldn’t take 3-inches or greater that cut out a large swath of potential candidates. Some MtBs can take 3 to 3.25 on the rear without issues though. Strangely my Marzocchi 888 RC3 EVO Fork can accept a 3-inch, though in real life – you want the phatty on the rear and not the front.

Pirelli & Innova: No, never did. I liked the Michelin and Continental better. It seriously crossed my mind to enlist ES members in the UK to fetch them for me and send them over. I was going to have Buchanan do me up a set of Excel rims with 9C 2807 hubs. I got as far as the stack of hubs when the EU tires bit me in the bum and I just had to have them! :twisted:

Weeks went by. It rained. I paced. Bit nails. Wore holes in my socks… dumb stuff; completely indecisive. Finally the engineer-lamp lit inside me and I had to force myself to stop and consider the classic problem of sole-sourcing (or limited sourcing) and took the 24-inch route cuz at least I can get rims and tires that I like easily here. And you know the rest.

  • The 26-inch rims with 9C 2806 hubs mounted are Mavic EX 729 DISC, but I never got around to putting them on the bike (P1). They were part of the original plan. If I build a bike for my Bro or a pal then these will go first; it’s a perfect match for the Maxxis Hookworms.
  • I didn’t worry too much about pedal strike; I’m chiefly an urban assault guy. That said my P0 ebike pedals annoyingly hit the steps when pull it into my hidden city bat cave.
  • Smaller size means more rotation to achieve the same speed, yes – but also more rolling resistance; this has more to do with angular velocity and efficiency. There’s a valid reason why racers like 700mm; easier to roll. But I wouldn’t worry about it too much since we have power-assisted drives. As for whether the slightly smaller tire will get to the same speed – that I think has to do with the BEMF. Hill climbing should benefit though, as will starts.
Last thoughts: Don’t get me wrong… Pirellis and Innovas though are good tires; I’m just a fussy butt and I want what I want. Why to the weird rules in the EU prevent them from sending them to us? Check out the Excel rims! If you decide to go to 24-inch, seek and find the Kris Holm vid of him off-road/DH taking drops on a unicycle! That was enough for me and I bought two. :wink:

Best, KF
 
auraslip said:
24" wheels leave me tiptoing at stop lights, but 20" wheels would risk pedal strikes on sharp turns.
Since you mentioned you were considering motorcycle tires..

The 17" moped tires/rims are "21 inch" in alternate naming, and they are available in appropriate diameter and width with street tread.. also you can get offroad tires in 17" also.. I laced some 17" alloys with fat knobbies on one of my little ice bikes that originally had skinny 18" tires on steel rims. There are tons of choices in tires and rims for 17" size on the moto side! Here's one link I've posted before:
http://www.jrbranson.com/hondaracer/honda/alloyrim.htm
from http://www.jrbranson.com/hondaracer/mainpage2.htm
They use these rims on the little 80cc motocrossers. Very strong..
 
I've found some more info -

The michelen Gazelle M62 http://www.bikebandit.com/michelin-gazelle-m62-moped-tire

18" 2.75 for $20

It will require an 18" 1.60 or 1.85" rim
http://cgi.ebay.com/ebaymotors/ALLOY-ALUMINUM-RIM-18-X-1-60-WM1-36-HOLE-HONDA-CB160-/150638992993?pt=Motorcycles_Parts_Accessories&hash=item2312c89e61

for $54

After (custom) spokes, tubes, hubs, and the rest It'll end up near $250
DAMN

But according to some calcs it'll give a overall diameter of 23.6" with a fat ass 2.75" tire.
This seems like the ideal height for us.

Useful links:
http://www.denniskirk.com/jsp/tpl/tire/tiresizeexplain.jsp
http://www.weeksmotorcycle.com/tire-size-conversion-chart.html
 
Back
Top