Mountain Bike Tire Size

Tire diameter for mountain bikes has been getting a lot of buzz and noise in the bicycle world in the last few years.  First, a bit of history; all Mountain bikes used to have 26” tires.  This was never due to any research or engineering.  It was because early mountain bikes developed from “klunkers” which were 26” cruiser bikes of the day.  Twenty six inch was simply what was available and fit the available frames. We all rode them and got used to the feel of them.  What you are used to is not necessarily the best.  Second, a bit of clarification: twenty nine inch mountain bike tires use the same rim diameter as 700c- (ISO 622) the most common size for road bikes.  The middle size of mountain bike tires is suffering from an identity crisis.  It is sometimes called 650b, not to be confused with 650c. It is also called 27.5”, not to be confused with 27”, the size of ten speeds from the sixties through the eighties.   Its ISO size is 584.  Although this name is not commonly used, it is technically accurate and not confused with similar names.

When considering a new mountain bike, get the largest diameter wheel and tire size that fits your body.  Larger wheels are faster because they roll over obstacles better.  The angle of attack against a rock, root or log is better with a larger diameter.  Twenty nine inch wheels pose some geometrical problems with smaller frames, so smaller riders are better served with the middle, 584 size. 

If you are coming from a 26” mountain bike and test ride both 29” and 584, you may feel more at home on the 584 size.  This is because it is closer to what you are used to, not because it is a better size for you. If you are big enough to fit on a twenty-niner, do it.

If you are not buying a new mountain bike, you will usually need to ride the size that the frame was designed for.  If you have disc brakes, you can substitute smaller wheels, but why would you want to?

Plus size Mountain bike tires are another new trend.  This simply means extra wide, but not as wide as a fat bike.  Wider tires give more traction and better comfort.  Many riders are enjoying the plush ride of plus size tires without the cost and complexity of rear suspension.  Remember that the original bicycle suspension was the invention of the pneumatic tire in the late 19th century.  It is still a viable form of suspension.

There are more options than ever for tire sizes.  I hope this article helps you decide, but if you still have questions please come on in and talk with us.  We can find the right tire for you.



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