Friday, May 17, 2013

The Wheels on the Bike Go Round and Round

I've gotten a few requests to have a conversation about tires.  I agree.  It's time.  The wheels of a bike are what carry you on down the road and there's a lot to 'em that has a really big influence on not only how strong they are, but how fast they roll and what you can carry.  So, as usual, let's break it down.

There's two pieces at play here - the actual wheel and the tire.  We'll start with the more expensive piece, the wheels.


On a bike wheel there are three pieces anyone cares about, and if you care to invest in custom-built wheels you can choose each individual component to your personal specifications.  The wheels are the second most expensive piece of a bike after the frame, and your perception of how a bike rolls is heavily influenced by what's called "rotating weight".  The idea here is that because the wheels are actually in motion, extra weight in them will slow you down more than an equivalent amount of extra weight in the frame (or drivetrain, or on you).

The hub at the center is a lot of what determines how easy your wheels spin.  Cheaper wheels have cheaper hubs, which have cheaper bearings on the inside.  You can do a lot to speed your ride up by using wheels with nice hubs.  The hubs and the rim have to match on one very important factor - the spoke count.  On road, mountain, commuter, and touring bikes there are vastly different preferences for an idea number of spokes to achieve the right balance of rotating weight and strength.  For the purposes of the Bike Month series, we're sticking with commuters.

To take two of my favorite bikes, the Surly Long Haul Trucker versus it's close relative the Surly Cross Check, this is one of the most defining differences between the standard builds.  The LHT is intended to carry heavy loads for long distances and comes specced with 36 spoke wheels.  The Cross Check is lighter, sportier, and not intended to carry incredibly heavy loads for incredibly long distances and comes specced with 32 spoke wheels.  They're lighter, so they're faster but there's a slight compromise in strength that comes into play depending on how much heavy-load carrying you intend to do with your bike.  I don't tend to worry about weight too much, but I put insanely heavy stuff on my bike so I like the extra spokes.

The rims are the last component of the wheel and come in a couple options - "single" or "double" walled.  Again, the double-walled rims are stronger but heavier and create greater rotating mass, so they're slower.  It's physics, they just are.  Rim choice is also dictated by the type of brakes installed on the bike - rim brakes need wheels intended for use as a braking surface.  Disc, roller, and drum brakes don't!

When these items are all sensibly chosen you should end up with a wheel that's strong enough to hold up.  Now, let's talk about size.

There are 4 wheel sizes generally in use today, only 2 of which you'll find on the majority of bikes.  They are:

  • 26 inch - found on mountain bikes, some touring bikes, and some hybrids.
  • 29 inch - found on awesome mountain bikes
  • 700c - found on road bikes, the majority of touring bikes, cyclocross bikes, hybrids, and city bikes.
  • 650b - this wheel size is pretty much exclusively used by bike nerds.  Don't worry about it too much.

26 inch and 700c are pretty much the only two you'll see when looking around for a commuter.  In my own case, I'm short as hell and as a result I chose a bike with 26 inch wheels.  Additionally a smaller wheel is stronger than a 700c, helpful for my needs as a heavy-duty commuter who occasionally throws a 40 lb bag of grilling charcoal on the back.  700c is the faster choice and for anyone taller than I am is a really, really great wheel.  They roll quick and the strength penalty for choosing a bigger wheel is so slight that for most folks it doesn't really matter.  I've had bikes with both size and liked both.  As always, my recommendation is to try some bikes in your size with each type and go from there.


So you've got a bike and it's got some wheels on it.  Now we need some tires.

While I spent an insane amount of text talking about wheels up there, once you've picked out some wheels or bought a stock-specification bike, you're probably not going to swap the wheels out too much unless you have pretty specific needs (training wheels versus racing wheels).  Tires though, are a consumable.  They wear out from use, abuse.  They get nails punched through them, slam over potholes, roll over goes on.

Tires are like handlebars - there's a few basic types but the permutations are nearly endless.  For commuting, there are quite a few city-specific tires, but here's the criteria you're looking for.


Whether you have an aluminum bike, a steel bike, a rigid or suspension fork, as a commuter the best thing you can do for yourself is get yourself some proper size tires.  For 26" wheels I tend to prefer between 1.5"-1.75," and for 700c I really like 28-36 mm widths.  For me personally, these tire sizes provide a sweet spot of narrow enough to get around quickly, but wide enough to provide some cushion and stability.

One limitation to "how big can you go" is a metric of a bike frame called "Clearance."  This is basically how much room you have before things start to rub, and different styles of bike "make room" for different tire widths.  In the case of my Surly LHT, the maximum tire width the bike can accept with fenders mounted is 2.1" wide.  Check with whoever made your bike - this is a number they will have available.

Puncture Resistance

Welcome to the bike lane - the land that road cleaners forgot.  As a commuter you will run over train tracks, nails, glass, huge bits of wire, and every other piece of godforsaken road debris that ever bounced out of the bed of a pickup truck and swept to the side.  Puncture resistance is the ability of your tires to run over all of that nonsense and keep on trucking.  For puncture resistance the usual recommendations are Schwalbe Marathons, Continental Gatorskins, and other tires with names that indicate their toughness.  I personally use a Continental Touring Plus, a tire marketed as a direct competitor to the Schwalbes for slightly less money and so far I have run over all kinds of nonsense without issue.  Tires that don't go flat are like air conditioning - you never think about it until something goes wrong.

Rolling Resistance

A tire with low rolling resistance glides over pavement seemingly effortlessly.  However, a total lack of tread can lead to unreliability in anything but perfect conditions.  So it's important to strike a good balance between easy-rolling and surefootedness.  Rolling resistance is partially a function of tire size - the skinnier the tire, the faster it is.  

In the end, tires are another balancing act.  You need to balance weight, puncture resistance, and speed with your own personal needs. 

As a final note - tire pressure.  The skinnier the tire, the higher amount of pressure is necessary for it to support your weight.  There's a recommended PSI range on the side of every tire sold in the USA.  For best performance including puncture resistance, rolling resistance, and general lifespan keeping your tires in that range is a total necessity.

Happy bike month, folks!  Wheel on.

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