Demystifying Mountain Bikes

This whatever-it-is is about options. You, discerning mountain biker, have a lot of choices.

The genesis of this jumble is my wife, a reluctant mountain biker if ever there was one. I bought her a really cool race bike many years ago, but she never got into it, largely because she thought both the bike and the sport were trying to kill her. Ever so slowly, as I started to ride more and more bikes, it occurred to me that my wife’s bike was waaaaaay too racy for her: too quick in the steering department and perhaps too aggressive in the riding position. Several weeks ago I built her a fat bike, and it fundamentally changed her relationship with off-road cycling. Heck, we were recently riding on a dirt road somewhere, and I looked back to see her riding without hands. Such a feat seemed beyond reality.

Against my better judgement, let’s sort out some mountain bike terminology:

  • 29er = big wheel = the same diameter as a road bike but generally wider. Increased diameter makes it easier to roll over stuff. 29ers have a bigger contact patch for greater traction.
  • 27.5 = bigger than a traditional 26” bike but smaller than a 29. Purported to be “the one diameter” by some folks, 27.5 has pretty much forced 26” bikes (with two exceptions; hold on) out of the market.
  • Fat bikes incorporate a tire not less than 3.7” wide, or at least that’s the low limit for most races. Fat bikes are traditionally built on 26” rims, but 27.5” rims are happening. The vast majority of fat bikes are rigid at both ends, but suspension is an option.
  • Plus bikes are relatively new things with tires 3” wide. Popular rims for plus bikes are 27.5” and 29” in diameter.


And now for a quick decoder ring on mountain bike geometry lingo:

  • Cross Country or XC bikes are light and fast. Steering is generally pretty quick. Suspension can go from zero to not terribly much, like 100mm (4”) of travel. Cross country is what most folks call our trails around here — lots of curves, not too much extended climbing or descending.
  • Trail and/or All Mountain bikes are generally a little more relaxed in the steering department than an XC bike. They’ll have another inch or so of travel and will weigh a bit more, dollar for dollar. Most companies include Fat and Plus bikes in their Trail bike lineup.
  • Enduro is probably next, and the emphasis definitely turns toward downhill riding and jump-ability. Enduro bikes are relatively heavy for these parts and typically have a pretty large amount of travel.
  • Last there are Downhill or Gravity bikes. I’ve seen exactly one honest-to-goodness downhill bike in Kalamazoo, owned by a customer who wanted to ride steep stuff out west. It seems odd to a midwesterner that a bike can cost $5,000 and still weigh about 40 lbs., but such is the stuff of downhill.


Back to the point of all this: many are the options. The advances of modern bikes are pretty darn great. Dang near every change in tire dimension has given mountain bikes a little more traction and made ‘em a little less nervous. Click here to find all the uses. The big meats on fat bikes are amazing, and the plus bikes strike a nice compromise between traction and weight. Geometry differences between a full-on XC race bike and a trail bike can have a massive effect on rider confidence.

And that’s what it’s all about, right? Fun. Zooming around the woods with friends. If you’ve thought that mountain biking was just not for you, I’d encourage you to give it another try on one of these new-fangled things. You might find something you like.