Tuesday, January 18, 2011

The Magical Wheel Size

In the early days of bicycles, they were direct drive machines. The bigger the size of your machine's wheels, the more ground you would cover in a single pedal stroke. The upper limit to wheel size was determined by the maximum extension of a human leg and the high wheeled Penny-farthings ruled the roads. Rear wheels on these machines kept them from toppling backwards without the rider needing a unicyclist's balancing skill, but the dreaded "header" (when the wheel stuck in a rut or struck an object and the rider flew off, head first) was always a danger. The 1889 American Eagle and Star bicycles addressed the header problem by placing the smaller, non-driven wheel in the front and making that the wheel that steered. Of course it would now be possible to fall backwards off the bike. I would love to think that falling backwards off your bicycle and landing on your bum was the origin of the word "bummer", but the folks who write real linguistic histories don't seem to agree with my theory.

The chain drive (which allowed a gear ratio to be selected independent of wheel size) and the pneumatic tire (which allowed small wheels to provide a smooth ride) led to the rise of the "Safety" bicycle. Bicycles with two smaller wheels of the same size became the norm and the high-wheeled Penny-farthing is now most often seen in museums, nostalgic advertisements and the occasional dandy tweed ride.

Some folks (myself included) just love to tinker with bicycles and over the years, a wide range of machines with various tire and wheel sizes have been tried. This is natural when you think about it. People come in different sizes, they ride bicycles over a variety of surfaces and they use bicycles in different ways. Different wheel sizes and different tires have different properties. No one wheel size will be perfect for every application, but every few years someone discovers (or rediscovers) a certain wheel size and it becomes "the greatest thing ever!"

Path dependence puts a lot of inertia into the manufacturing and marketing loop. If you are going to invent something like a mountain bike you wind up building the early ones out of parts you have: old Schwinn's from the 1940s because they had the big cushy tires, gears from the skinny-tired euro-bikes. Graft them together for Mountain Bike 1.0. And for at least the next decade mountain bikes will have wheels that have a diameter of 26 inches, the same size as those old Schwinn paper boy bikes. But is 26" the best size for a mountain bike? Some folks questioned that and now a bunch of those folks are riding 29ers. Guitar Ted put together a great history of 29ers and it is fascinating reading.

Now I love riding my 29er. The wheels do have more inertia, they roll over some things easier and so forth, but 26 inch wheels have certain advantages as well. In some cases (lots of starts & stops or very twisty trails) smaller wheels might be better. Reasonable people can have reasonable reasons for riding a bike with different size wheels.

On the road bike side of things, some people love, love, love 650B wheels. These are smaller in diameter than the now dominant 700c wheels. You can build a frame to that allows cushier tires or in some cases retrofit this wheel-size into a 700c frame (you need to find some longer reach brakes) and then you can get the cushy tires and your life will be wonderful. Or so the 650B folk tell me. It's the same sermon the 29er folks preach but going a different direction. And I've also heard from some folks that actually 650B is the perfect mountain bike wheel size as well. My pal Beth has a great heretical rant about 650B wheels.

I actually think that there is no magic, perfect wheel size. It's not magic, it's physics and physiology and psychology and something about different horses for different courses. My 29er is a great bike and I like winding the big wheels up to speed and letting 'em roll down a long, rugged trail. But I still have a 26" wheeled mountain bike and by golly it's lots of fun and I ride it a bunch. My 16" wheeled Dahon folder is light and fast and the little wheels spin up in an instant. It is my favorite bike for many rides and it lets me buzz around town like a hummingbird. The little wheels are quick, but it's not as fast on the long haul as a big wheeled bike.

Some people seem to think that everything is evolving toward some perfect end, but from what I've seen the world doesn't work that way. We have whales and hummingbirds, turtles and cheetahs. And as long as we have bicycles, we'll probably have them in a variety of shapes & wheel sizes. I think that's pretty cool. Heck, it's damn near magical.

Keep 'em rolling,

Kent "Mountain Turtle" Peterson
Issaquah WA USA


jnyyz said...

650b, bah!
If you look at the bikes in my garage, the most common wheel size is 20" (406).

and yes I need to weed my collection.

chatty cathy said...

great post kent. luv the way u just ride "what you have" and make it all work.
i think 650b is the dumbest thing in cycling. it is only 4% bigger than 26" MTB. 4% doesnt matter unless u are someone with nothing better to do than to flood internet forums with how it "changed yer life". but lets face it, we are a nation of consumers........

JuliaR said...

I don't know if you've ever read "On the Bummel" by Jerome K. Jerome, but I recommend the first part anyway, where he writes about bicycles. Parts made me laugh so hard, I had to put the book down for a while. It was published in 1900, but I believe they must be riding safety bicycles, especially as they have a tandem. Enjoy! (I got it from the library but I think my husband got a free copy on his Kindle, when he went looking for it.)

NickBob said...

The pennyfarthing was also prominently featured in the old British TV series, The Prisoner.
"I am not a number, I am a free man!"

Jan Heine said...

I think your analysis is spot-on. The important thing is to realize that different wheel sizes behave differently. You can't just use the same geometry for a 700C x 23 mm tire and a 700C x 40 mm tire, and expect the bikes to handle the same. (And it makes little sense to equip larger frames with larger wheels just to keep them in proportion. Physics don't scale that way!)

At Bicycle Quarterly, we found that we like a certain handling, which correlates to a certain gyroscopic stability. For 32 mm tires, that means 700C wheels. For 40 mm tires, we prefer 650B. For 45 mm tires, we think 26" handles better. Once you know how you like your bike to handle, but want to try a different tire width, you can scale your wheel size to keep the handling similar.

Anonymous said...

Count me as another rider against 650B. Wouldn't ride it even if it was free!

Ted said...

Kent, Thanks for that article. It was an eye-opening experience to measure my mtb rim and see it barely bigger than 22.5 inches and the 700c road wheels to be smaller.

My question to you - would you ever ride a 29er bike for the Tour Divide?

Dexey said...

I'm with jnyyz on this. 406 rules (except on my Brompton)
Three wheeled or two wheeled, upright, folder or recumbent; I'm on 406's. Even the custom made frame had to go once I'd discovered the delights of the 406! :0)
Next experiment is a hub geared 406 to see if I can get enough off road clearance.

Jason T. Nunemaker said...

I think those 16" wheels on your Dahon could be the Next Big Thing if they just had a trendy name and a marketing campaign. Remember when 700c was just 700c? Then some genius came up with "29er" and kerblammo - instant cache.

I propose "Sweet Sixteeners." Just cut me in on the flood of profits that are sure to follow. :-)

Jason "Former Ad Man" Nunemaker, slowly buying back his soul in Des Moines, IA

kfg said...

Three Men on the Bummel is available from Project Gutenberg and LibriVox (for you heathen). It is a hoot and you would be hard pressed not to recognize your friends in it (you're there too, but you might not recognize that).

"Physics don't scale that way!"

The bastards!

Drew Devereux said...

It's nice that there are so many wheel sizes; there are advantages and disadvantages to all them, as you point out in your post!
I think it comes down to a matter of preference.

I recently made a cargo bike with dual 406 wheels which rocks:


I don't understand why the typical bakfiets has a larger wheel on the back though, while the front is a 406. Maybe just to keep one wheel looking conventional?

Alexander said...

Excellent post, and very instructive textual production is well done, congratulations, not counting the images that are true relics, here where I live has developed a mechanical one such bike, when I saw thought it was the citizen, and crazy, because it is revolutionizing something new, then I could verify the existence much earlier, and not an innovation as expected. Congratulations, indeed.

Velomann said...

"Reasonable people can have reasonable reasons for riding a bike with different size wheels."

Not sure whether you meant different bikes, or different sizes of wheel on a bike, but those exist too (besides on a Penny Farthing.) I had a friend back in 80-something who had a Cannondale MTB that had a 26" front wheel and a 24" rear - and I'm pretty sure that was stock. Maybe others beside Cannondale did it too. Something about better climbing and a lower butt with the smaller rear wheel, and better rolling over rough stuff is why the front stayed 26". And I've heard others make the same argument for a mixed 29 front/26" rear MTB, though I have yet to see one in person. And of course time trial bikes with smaller 650c front wheels to get a better aero position used to be pretty standard.

amoeba said...

by JEROME K. JEROME is available for free from Project Gutenberg in various editions including Kindle.

roan said...

Great post ! When traveling I look for bike museums, few and far between but worth it. A picture says a thousand words but the real thing...priceless...even if you can't touch.
650 conversion needing longer brake calipers...switch to disc using "Therapy Componets". I'm thinking of switching one of the road bikes to disc using this system.

roan said...

If'n the tires were not so hard to find I like the idea of even bigger wheels...like 33" or 36" (uni-cycle) wheels. Need a frame made that lowers the center of gravity and puts the rider below the top of the wheels, just for fun.

Anonymous said...

I'm glad we have a wide range of supported wheel sizes, since they solve varying design issues. Let a thousand tubes inflate!

But, 650b is primarily an excuse for the wealthy bicyclist set to add to, or replace their stables. And then, write rhapsodically about their new "French" lifestyle in BQ.

Don't get me wrong, I love to read the stuff. I loved it when that set was all about Riv, too. Wait a couple years and they'll be just as passionate about something else. Maybe mini-velos for randoneuring. Or penny-farthing mountain biking. And they'll have valid scientific studies proving the overlooked greatness of the wheel sizes, rakes, etc. The truthy-sciencey stuff is the funnest to read.

True enough, the 650b may be a solution for a relatively narrow set of riders with sizing issues (as might other wheel sizes between the US 26 or the 700, some of them now defunct). Though, most of those riders would really rather have 700s. And I think 650b is fine for the persnickety who can afford to "dial in" an illusive sense of "gyroscopic" performance. But, we're talking about performance margins smaller than giving up that extra beer and losing some gut. Tire and wheel size correlations? Bah. Have another Jenlain and forget about it.

I'm a little troubled when naive average Joe or Jane buyers get a sales job on the 650b. Really, a wheel size is not all that. A wheel size won't make you magically spout existential epigrams while knocking off a triple century.

No wheel is an island. You will need to buy tires and tubes for the life of the wheel, maybe at times and in places you won't expect. It's nice to have both ready availability and a variety of choices. That's not 650b.

So, most of us, for most "safety" bikes, most of the time, have to first rule out 26 and 700. Two excellent wheel sizes, btw.

But, I admit the wtf hobbiest in me would like to see some industry-supported monstrous wheels like roan describes. Maybe the hammock style frame could have suspension.

Somebody in Portland is probably building that bike right now.

BQ will endorse the wheel size in 2014.

jimmythefly said...

I think one thing missing is the crucial notion that it's not necessarily the 650b size in the sense of "what's the optimum wheel size when starting from scratch". If I'm understanding path dependence, I think it applies here too:

Question: How do I get some nice, wider tires on a nice "classic" steel-framed bicycle? The list of classic-type steel frames that fit 700c x 32 tires with fenders is a lot shorter than the list for those that fit 650bx32 tires with fenders. To add momentum to this, many folks already had a fantastic fully built-up frame that would fit fatter 650b tires, so instead of sourcing a new frame, they only had to source wheels and brakes.

Also @ anon above me "No wheel is an island. You will need to buy tires and tubes for the life of the wheel, maybe at times and in places you won't expect. It's nice to have both ready availability and a variety of choices. That's not 650b."

The flipside to that is: No wheel is an island, and I have yet to hear of a 32, 38, or 41mm 700c tire that match the best of the 650b tires. I'm usually all for variety, but there's something to be said for three excellent choices vs. a thousand good choices.

Anonymous said...

What, no love for reviving US 27 inch wheels? Tant pis, I guess.

Like the 700, the 650b mostly seems to cannibalize existing wheel categories. It's just different enough to be annoying.

Unlike, say, Surly's Pugsley wheel. Maybe the Pug wheel gets overlooked in these discussions because it's a width revolution rather than an incremental diameter variation.

The large margey thing opened up new terrain and new styles of biking (for good or ill). The 650b just goes where a zillion 26s, 700s...and 27s...have boldly gone before.

The Pugsley is of course also a frame redesign of course. But, that just clarifies that a wheel alone cannot solve clearance or other issues.

Props to the disk brake btw, which allows diameter experimentation on the same frame.

kfg said...

Anon - I once threw together a Frankenstrousisty that ran on truck inner tubes for tires as a snow/swamp bike. Then I found out that I wasn't anything like the first to try that.

It is very, very hard to "revolutionize" something that reached its optimal state of design 100 years ago.

"Props to the disk brake btw, which allows diameter experimentation on the same frame."

Case in point, so does fixed wheel, so the early experimenters were not hampered in that regard. Fixed gear road racing bikes even used the front and rear OLD the same trick in order to have four different size cogs available.

Anonymous said...

Hmmm...how about we call the pugs wheel a width "reformation"? I don't think the point was that the super-fat tire idea was original.

Surly's wheel (and its imitators) isn't a one-off custom. It's pretty fair to compare it to the 650b. Both are small-scale parts-supported commercial production models.

The pugs wheel is obviously more deviant from the 100-year optimal norm than the 650b. The performance claims for the incrementally different 650b seem a bit hyped, but the claims for superfat tires less so.

I wouldn't be surprised if there were an earlier vision of the bicycle disk brake, but I don't know of a production version. I suppose if there was never any progress in design we'd all still be relying on spoon brakes. Haven't seen one of those in...oh..a hundred years or so.

Actually, kfg, I'm thinking your adoption of truck tubes on a bike (and similar experiments) leading to the production surly wheel probably was a similar invention trajectory to the adoption of the production disk brake to bicycles. Wasn't the disk also imitated/adapted from motorcycles?

LBJ said...

Hm...I think that 650B is a good option if you're too small for a standard size road bike - sometimes for women especially, it can make for a much better riding position, however I agree that they're a total pain to find sometimes, and while I'm also on the small side, I have adapted to the slightly larger 700C wheel size for convenience etc.
And yes, different wheel sizes are appropriate for different purposes, however I think it should be noted that not all folding bikes have small wheels - I have a folding bike with full size wheels.

karmapics said...

wheel sizes when all is said and done are just semantics. They're still round, right? This is like the Mac/PC argument. They both do the same exact thing, they both have the same problems (even though one faction would beg to differ) but at the end of the day they're just tools to do what you want. Personal preference.