Wheel sizes for Leap Conversion

Please note: The FreeRadical Leap conversion kit is retired and no longer in production. For more information, including tips on how to find one used, see here.

The Leap DIY Cargo Bike Conversion Kit is designed to work with a wide range of wheel sizes from 20" to 29+. It has capability for a much wider range of wheel sizes than the old FreeRadical. We designed it as such because available wheel and tire sizes have proliferated since the days of the FreeRadical, and we believe that there's a lot of fun to be had with some of these new sizes on a longtail cargo bike. We know you feel the same way!  

The supported wheel sizes for Leap conversion are: 

  • 20" (406mm BSD), commonly found on some folding bikes and minivelos.
  • 24" (507mm BSD), commonly found on some folding bikes and small mountain bikes.
  • 26" (559 mmBSD), commonly found on mountain bikes, cruisers, some city/comfort bikes, and some touring bikes.
  • 26+/26x3.0 (559mm BSD), found on newer "plus" tire mountain bikes like the Surly Instigator 2.0
  • 650b (584mm BSD), commonly found on some touring and city bikes.
  • 27.5" (584mm BSD), commonly found on some newer mountain bikes.
  • 650b+/27.5x3.0 (584mm BSD), commonly found on newer "plus" tire mountain bikes.
  • 700c (622mm BSD), commonly found on road bikes, hybrid bikes, cyclocross bikes, some city and comfort bikes, and touring bikes.
  • 29" (622mm BSD), commonly found on some mountain bikes and cruisers made after 2000.
  • 29+ (622mm BSD) commonly found on newer "plus" tire mountain bikes.

In terms of The Leap frame itself, it is one size fits all when it comes to tire and wheel sizing; there are not different Leap frames for each wheel size. So if you're game to try out a Leap conversion, and your bicycle meets the specifications listed in the Leap Compatibility Guide, you can be confident that you're ordering the right frame.  

This also means that you don't have to be limited by your original conversion frame. If your first project is installing it on a cool 26" hardtail mountain bike, but a couple of years down the line, you start looking at your 20" folding bike bike, thinking its small wheels might be good for cargo hauling, go for it!  Your original Leap frame will work on both bikes.  

Gettin' crazy with wheel sizes

Some of you will be reading this and thinking, "But wait...if one size Leap fits all wheel sizes, why be constrained by the wheel sizes of your existing bike? Can you use the Leap to "Monster Truck" a bike designed for smaller wheels with bigger ones? Can you use a smaller rear wheel in back to lower the center of gravity?"

Great question! The Leap is designed to work best by working with the geometry of your existing bike, which means keeping wheel size basically the same. Using different size wheels than your bike is intended to take can be done, but it will drastically affect your bike's geometry and handling, and may cause the Leap to not function properly. Specifically, using a smaller rear wheel than the bike is designed for will make the head tube angle and seat tube angle significantly slacker, and significantly reduce your bottom bracket height. In addition, it may cause ground clearance issues with parts of the Leap frame and some components, such as the U-Tubes, KickBack kickstand, and the rear derailleur. 

However, the huge tire clearance of the Leap--up to 3" wide--and the fact that it uses disc brakes means that you should't feel constrained by the existing tire sizes on your bike. We definitely encourage you to try wider tire sizes with your existing wheel size, especially if you can match the upsizing on the front wheel. Fatter tires and cargo are a really great combination.

Wide tires and chain clearance

While the Leap frame will have no problem clearing tires up to 3" wide, some bikes with derailleur drivetrains may experience some contact between the chain and tire when running wide tires. The longer chain run on a Leap-converted bike means that even if the original bike doesn't have chain clearance issues, the converted bike may run the chain closer to the tire while in the lowest gears (closest to the centerline of the bike). This will be especially true of bicycles with smaller wheels (20" and 24") and 11 speed drivetrains. In some cases, the chain rub may simply be an annoyance, while on other bikes it may be problematic. Coming up with creative solutions in the situations where it is problematic is one of our goals for the Leap Beta testing phase. 

What about fat bikes?

Fat bikes (defined as bikes using 26" wheels with 4-5" tires) are not currently listed as supported for Leap conversion. This is for two reasons: first, pretty much every fat bike uses either an offset rear end or a super wide rear dropout spacing, in order for the drivetrain to clear the super fat tire. Since the Leap was designed for bikes with symmetrical 135mm rear spacing, our stock mounting hardware probably won't work with a fat bike frame. Second, the Leap frame, when assembled as designed, would have trouble clearing any tire wider than 3", not as wide as a true fat bike tire. However, there may be ways of modifying or fabricating new mounting hardware to match fat bike spacing, and modifying the rear end of the Leap to increase the clearance. If you have a fat bike you want to convert and are up for the challenge of figuring out how to make it work, go for it! 


Have additional questions about Leap tire sizes that we weren't able to address here? Drop us an email at support@xtracycle.com and we'll do our best! 

Did this answer your question? Thanks for the feedback There was a problem submitting your feedback. Please try again later.

Still need help? Contact Us Contact Us