32” Wheels for eBikes

Learn About Large Wheel Electric Bikes

This has been a really fun project from the beginning. When Jusuf Nurkic called and told us his last Custom Zinn Titanium Gravel bike got stolen, we wanted to replace it with something really unique. Since he is 7’ tall and 275lbs and plays center for the Portland Blazers, we decided that we could do something truly special to enhance his riding experience.

Check out what we did to upgrade his ride here!

Bigger Wheels Are the Key

When we were discussing the customization of his bike, he told us that he felt the 700 x 35c tires on his first bike were a bit small for him. He hoped to have a bike perfect for cruising around Portland that would feel substantial underneath his mass. After much discussion, we decided that a 32” wheeled electric assist bike was perfect for him.

This would be the first bike we built with 32” wheels and, to our knowledge, the first titanium 32” wheeled e-bike in the entire world! When building such a large wheeled electric bike, there are a lot of factors to consider, including:

Tire and rim availability is a challenge, but we were able to source Nimbus rims, 32″ x 2.25″ tires, and tubes from Unicycle
No one makes a stock fork for a 32” wheeled bike, so we custom-made one in steel since titanium would make for a very flexy fork.
With such big wheels, stiffness is a potential issue. We built the wheels with 36 spokes and wide hub spacing. This one has 12 x 157mm rear hub spacing and 15 x 150mm front hub spacing. This gives the spokes enough outward angle to make a stiff wheel.
We achieved rear triangle stiffness with an extra-large seat and chainstay tubing.

Bike Specifications

Since Jusuf wanted a large wheeled electric bike, we were able to have a custom 3D-printed titanium motor bracket built for the Bosch Generation 4 Performance line speed motor that has 85 Nm of torque and 790W max power behind it. That should be plenty for a 7’ tall NBA player to rally around the city and even head up into the Oregon mountains.

We used the newer Kiox Display from Bosch, which conveniently disables the motor when removed for security against theft. This bike weighed in at 50lbs, which ain’t bad for a gigantic e-bike with huge, 32” wheels.

Testing the Ride

The big question for us now is, “How does this bike ride?” Well, we were all blown away by how fun it is to ride. It’s super-fast and corners like it’s on rails. It gives the rider an incredible sense of stability and resistance to being deflected by bumps, thanks to the enormous rotational inertia of the wheels, especially at a motor-assisted speed of up to 28mph. The bike also has drop bars, which really allow you to get aggressive with your ride. It’s one of the most fun bikes we’ve built here at Zinn Cycles.

It took a few tries with different chainrings and cassettes to get the gearing exactly how we wanted it, but we ended up with a 38t chainring and a 10/42 rear cassette. Sram Rival Components and Onyx Racing Products hubs were a great addition, too. By scaling the wheel size up along with the size of the frame, cranks, and handlebar for such a large man, you get a bike that looks very normally proportioned. Unless it’s next to a normal-sized 700c road bike, you wouldn’t guess that it was built for a 7’ tall man.

Future Custom Builds

We hope to build more of these 32” wheeled bikes in the future. It makes for a great bike to cruise around town or ride local bike paths. We still think 700 x 28mm is the best choice for a performance road bike for many reasons, and 700 x 35c is best for gravel bikes. But, who knows what will come of the 32” wheel size in the future. Maybe, more tires and rims will become available, making it a more viable and proportional road or gravel bike for a very tall rider. For now, we can do e-bikes or regular bikes with 32 or 36-inch wheels in steel or titanium with either flat bars or drop bars.