207-847-0228 Casey@kbwheels.com
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Every year the bicycle industry comes out with new and “improved” products.  Honestly, most times I can’t tell the difference between the old and the new and improved versions.  Sometimes I even like the old version more.  A few years back the next big thing was wider road rims.  As a wheel builder and engineer I’m always interested in new wheel products so I purchased a set of rims with a 19mm inside width (as opposed to the then normal 13mm) and built them up.  On my first ride I was blown away.  The difference was dramatic, especially in cornering and as an engineer it made sense.  To help you visualize what I’m talking about I’ve attached a graphic showing exaggerated rim/tire profiles; the 13mm  rim profile produces a shape like a light bulb, and the 19mm rim produces a rounder tire profile.  I’ve drawn in an approximation of where the centroid and the moment arm are for the two profiles and you can see the moment arms are different and this difference is important.  The difference between the two profiles is most striking when cornering.  The light bulb tire, with the larger moment arm, tends to fold or bend over producing a feeling of instability.  The rounder tire with a smaller moment arm holds its shape much better, and the feeling of greater stability is obvious.  And the harder you corner or the heavier you are the more force you apply and the more you feel the difference in stability of the two profiles.  Riders also mention that they can run lower tire pressure with wider rims, making for a more cushioned ride.  This is also due to different moment arms because with the light bulb tire a higher tire pressure is needed to counter the folding due to the greater applied torque or moment.  With a rounder tire and smaller moment arm you don’t need as much tire pressure to counter the effect.  In conclusion, wider rims are a vast improvement over narrow rims, and if you aren’t on them then you are missing out (IMHO) on better bicycle handling and comfort.  KB Wheels would love to get you on a set of new custom handbuilt wheels with wider rims so you can experience comfort and cornering at its best even at lower tire pressures.