CHANGE bike mods: 27.5″ wheels


August 13th 2018

Every so often, we get some news from folks who are modifying their CHANGE bikes. This is doubly useful because it does two things. It:

  1. Provides instant useful guidance for any other customers or potential customers who are considering the same changes.
  2. Helps us and our manufacturer identify where customer needs are headed for future model changes.

Today’s feedback is from Gene, who converted a CHANGE 612 mountain bike from 26″ wheels to 27.5″ wheels…while also INCREASING the tire width.

Bigger wheels, bigger tires, and tubeless: Three adaptations in one.


612 modified.

The CHANGE 612 frame was designed for 26″ wheels. But here it is with 27.5″, in a customer mod.

Gene is a discerning MTB rider who routinely puts in a lot of miles. Here is the upgrade process in his own words.

After 10 months, my stock rear tire had little tread left and kept getting flats.  I got tired of replacing tubes and decided to go tubeless.

At the same time, I felt that the stock bike was a little underpowered in high gear and the solution was either a larger pedal sprocket or a larger wheel.   Since I read in the blog that 27.5″ wheels would fit the 612, I thought that would be the way to go.  I settled on Mavic Crossmax 27.5″ wheels and originally was thinking about 2.1″ tires, but then I got a good deal on a wheel set with 2.25″ tires, which turned out to be Pulse Pro.  I couldn’t really find specs on them but went ahead and ordered them.

When they arrived, the cassette and discs switched without a hassle and I had to only slightly adjust the derailleur.

When I mounted the wheels, I found out that I had only about 1 mm clearance on the front wheel and 1.5 mm on the rear wheel with maximum psi (see pics).

Tight Rear Clearance

Tight rear clearance: 1.5 mm with 2.25″ tire.

Even Tighter Front Clearance

Even tighter front clearance: 1 mm with 2.25″ tire.

So those of you who want to upgrade, 2.25 seems to be the largest tire one can fit on the Change Bike with a 27.5″ wheel.  I haven’t really assessed the weight difference, but my guess is that either the stock and Crossmax wheels are about the same or Crossmax slightly lighter.

That’s a super-tight fit! Any regrets?


The short version is, I am really happy with it…



  1. The new tires are a lot quieter, they require 8 less psi than stock tire to max pressure, and are easier to pump up with a hand pump. (Those of you who have tried to pump up the stock tire to max know what I am talking about.)  Also, since there is a lower PSI, the tires are less stiff and more comfortable to ride.
  2. I carry a sealant and, unless it’s a large hole, a flat can be fixed on the road without having to remove the wheel or tire.
  3. The stock cassette and sprockets are much better match to the 27.5″ wheel as far as I am concerned–this is probably subjective–and I achieved higher speeds in high gears.  I did several test runs and averaged 5 minutes less on a 7 mile course with the 27.5″ over 26″ wheels.


  1. The larger wheels do take up a little more real estate; So far I have not tried to stow the bike in its bag to see if it’ll still fit.
  2. With the 2.25″ tires, there is very little clearance, which doesn’t bother me, but the sand and little rocks that get picked up by the tire get cleared by the frame and fork and takes a while to get used to it.
Bob, overall I think this is a great upgrade, especially with the tubeless tires and you may want to consider offering the larger wheels to your clients.  If you had that option when I was buying the bike, I would have gone for it.

Flatbike perspective.

Message received, Gene! We’ve now seen customer upgrades to 27.5″ on both the CHANGE 612 and CHANGE 609 mountain bike. Clearly, this is something that some customers are interested in, while others are interesting in minimizing the folded size for a full-size mountain bike.
We are currently evaluating this option at the manufacturer level, with a frame revision designed for 27.5″. Once it has passed the rigorous testing and ruggedness certification expected of CHANGE frames, we’ll have more news on that option.


Until then, thanks for leading the way!


Bob Forgrave,
President, Flatbike

Biking made easier.




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