Convert your adventure gravel bike into a light, fast, road or gravel bike with a 750D wheelset!

By Lennard Zinn

Gravel bikes now often come with 50mm tires, and adventure gravel bikes often have 55mm tires. This opens up a whole new arena of what’s possible to do with these bikes with swapping wheels and tires. Since two inches equals 50.8mm, that makes it practically a 29er! In fact, early 29er mountain bikes came with 29×1.95” or 29×2” tires, which is the same rim and tire size as 700x50C. And drop-bar 29ers for adventure bikepacking and dirt singletrack riding come with even bigger tires. For smoother roads and trails, these bikes will roll faster with taller wheels and narrower tires.

Big, knobby MTB tires and fat gravel tires at low pressure make riding rough dirt roads more comfortable and consequently faster. However, they are cumbersome on paved roads. Wide, soft tires with knobs rumble along slowly on asphalt. You can hear the increased rolling resistance in the tire noise; that’s energy you have put into the tire given off as sound waves (and heat) due to the extensive contact of the tires with the road. The larger footprint of the tires and the energy lost to hysteresis in compressing and releasing the soft knobs and tire carcass as the footprint moves along increases friction and thus the energy required to maintain speed. 

Also, the wide, grippy contact patch at low pressure causes 29er tires to respond slowly and inefficiently to steering inputs on pavement as the wide area of knobs scrubs across the asphalt to initiate a turn. That’s very different from the immediate response of a firm road tire when the rider countersteers by pushing their inside arm forward, putting the bike into an immediate inward lean and carving the turn.

Happily, when you don’t need those big tires to cushion a rough ride or support heavily loaded packs, that same bike can become a fast-rolling road or gravel bike by exchanging the 29er wheels for taller 750D wheels with smaller-width tires. With the same diameter of the inflated tires as the big 700C/29er tires it was made for, the bike maintains its original bottom bracket height and pedal clearance as well as steering geometry. With a wheel change, that bike becomes a Swiss Army knife—incredibly versatile over a wide range of conditions from fast road riding to heavily loaded dirt bikepacking.

WTB introduced 750D rims and tires because they roll faster than smaller wheels. The low angle of attack of the tire with the road and the longer, narrower contact patch means less deep compression into the tire under the same load and hence less energy lost to hysteresis.

A 750 X 34D WTB Byway “Dirt-Centric Road Plus” tire has the same inflated diameter as many 29 X 2.2” and 29 X 2.25” tires and is only slightly taller than many 700 X 50C tires. It has the same tread with a smooth center rib that rolls fast on pavement and side knobs for dirt cornering as the 650B and 700C Byway tires. 

And an inflated 750 X 40D WTB Nano gravel tire is just as tall as many a 2.3”, 2.35”, and 2.4” 29er tire. Its knobby tread with a “nearly uninterrupted centerline provides swift efficiency on hardpack terrain while staggered outer knobs allow you to stay on the gas while hammering up chunky climbs or hanging on through loose gravel corners.” Put a 750D Nano on a drop-bar 29er, and you have a lighter bike for fast gravel and cyclocross riding on hardpack, dirt and gravel roads and trails.

At Zinn Cycles, we can build for you the same 750D wheels that come on our Clydesdale Team 750D Titanium All-Road Bike. We also carry the WTB 750 X 40D Nano and 750 X 34D Byway tires to fit them. Increase the versatility of your drop-bar 29er or fat gravel bike by adding one of our 750D wheelsets to your quiver!

As a frame builder, Lennard Zinn has been designing and building custom bicycles for over 42 years; he founded Zinn Cycles in 1982 and co-founded Clydesdale Bicycles in 2017. His Tech Q&A column on Substack follows his 35-year stint as a technical writer for VeloNews (from 1987 through 2022). He is a former U.S. National Cycling Team member and author of many bicycle books including Zinn and the Art of Mountain Bike Maintenance, Zinn and the Art of Road Bike Maintenance, and The Haywire Heart. He holds a bachelor’s degree in physics from Colorado College. 

Follow Lennard Zinn on Substack, Strava, X, Instagram, LinkedIn, or Facebook.