It feels like a long, long time ago, but in my last entry, I introduced pedal sizes (do you remember...?). This time, I’d like to talk about a component that’s even closer to the ground: tires.
Over the past few years, the lines between road bikes and MTBs have blurred. New bike concepts like gravel bikes and all-road bikes have emerged, frame tire clearances have increased, and a wide variety of tire sizes have been developed to match.
While the range of tire profiles has expanded, recent innovations have made it so that simply changing your tires can drastically alter your ride quality. In extreme cases, if you have a bike with a similar concept, changing the tires now makes a bigger difference in ride feel than changing the frame itself.
Also, with disc brakes becoming the standard, more bikes can now accommodate both 700c and 650b wheels. This means that by owning wheels of different diameters, you can change the character of your bike to suit your purpose.
Combining these two points, it means you can explore various options for a single frame based on your needs for terrain, purpose, and ride feel. With a little ingenuity, you can get more out of the bike you already own. It’s truly a fun era that demands a rider's creativity (and if you put in the effort, you can have a ton of fun without spending a lot of money).
Do you know the maximum tire size your bike can take?
You might as well make the most of your bike's capacity and enjoy choosing tires that match your riding style.
Do you have a firm grasp on the sizes that fit your bike?
Tire size depends on your frame and rims!
These two factors determine the tire sizes you can use.
- Frame/fork clearance
- Rim width
First, let’s check what tire sizes your frame can handle.
Start by checking the allowed sizes listed on the bike manufacturer's website or catalog!
Official manufacturer information is the gold standard. If you use tires outside of their listed specifications, you can't really complain if something goes wrong.
...That’s the official line, but a bike that fits tires with barely any clearance left to spare just looks cool.
If there’s one brand that really "gets it," it’s Crust Bikes. They list pretty tight clearances. In reality, the safety margin varies from one manufacturer to another.
For instance, our staff member Kimura's Doppo ATB has Super Yummy tires shoved in that exceed the official max clearance for the frame, and it looks incredibly cool.
The beauty of cycling is that you can tinker with things at your own risk. Once you discover how to hack your own bike, you’re on the path to freedom. With your own ideas and vision, even a mass-produced frame can become a bike that is truly and uniquely yours.
As a bit of a pro tip, sometimes you can get a tire to fit by adjusting the wiring or other small details—it’s something you have to figure out by trial and error on the bike itself.
Sometimes there’s no info on allowed sizes, or you might have a used bike with unknown specs. That’s where bike shops like us come in. The scope of what we can answer via email or chat is limited, so please bring your bike into the shop and let’s consult. We’ll talk through the possibilities with all our might.
1. Measuring Frame Clearance
With that said, here is how we look at whether a tire will fit.
To install tires, we measure three areas: the fork, the chainstays, and the seatstays.
Use a ruler, tape measure, or calipers (calipers are better) to measure the inside width of the frame.
Next, we measure the distance from the top of the tire to the frame. Even if the width is fine, it won't fit if it rubs against the top.
By the way, there is about a 10mm difference between 650 x 47b and 43b, so don't forget to check this when making a significant size change!
Once you measure it yourself, you'll understand how much clearance each manufacturer leaves.
This space is meant to ensure that the tire doesn't rub due to mud buildup or wheel wobble. If you install tires that are right at the limit of your frame or fork width, the frequency of rubbing increases, which creates a safety risk.
I’d love to discuss the pros and cons of these things with you.
2. Is a 700 x 43c tire actually 43mm wide?
Sizes like 43c or 2.2 inches refer to the tire width when inflated, but the marked size and the actual measured size are not always the same.
The width changes depending on air pressure and the rim it’s paired with. Also, because they are rubber products, there are inevitably manufacturing tolerances.
It’s difficult to get identical sizes, and there are countless rim combinations out there, so be careful: if you use tires that are too wide, they might interfere with the frame and strip off the paint.
And don't forget that inner tubes come in different sizes, too. Remember to check your tubes when changing your tires.
3. Checking rim width
For this as well, first check the official recommended size on the web.
The information you need is the internal rim width shown in the image (the one marked 21mm).
For example, VELOCITY provides a list of recommended tire sizes for each of their models, so you can see at a glance which tire widths are compatible.
If you install tires that are too narrow, the beads might not seat properly, causing the tire to wobble; if they are too wide, the tire may squirm during cornering, causing you to lose balance.
To ride safely and happily, you really want to choose tires that match your rim width.
Some wheel manufacturers don't specify recommended sizes, so you might want to use this VELOCITY chart as a reference. (This is just a reference, so if you are worried, please feel free to ask us staff.)
Tires are a component that makes it easy to feel the changes in how your bike rides.
Let’s enjoy cycling even more by changing tires—the perfect component for experiencing your usual roads in a new way and aiming for a bike that suits you better!
