from Rookie’s keyboard,
Hello, friends
This morning I hopped on hardtail and went for a ride. It was nice, to be honest. I’d forgotten how it feels to ride a bicycle with a suspension and wide tires that just eat everything.
The experience inspired me to write an MTB post too.

Today, I will talk about the size of tapered forks.
It’s actually simple to understand. Tapered forks have a steerer tube with a 1 ⅛” diameter at the top where the stem clamps and a 1.5″ diameter at the bottom near the fork crown.
You see, fork manufacturers have an obvious incentive to keep their product compatible with a maximum number of frames. Hence the size stays the same.
That said, the length of the tapered section could vary between models. This measurement, however, has little effect on the fork’s compatibility with different frames.

1 ⅛” Top
Threadless stems are designed for 1 ⅛” steerer tubes. Tapered forks have to respect that measurement or else they won’t work with standard stems.
The default steerer of threadless forks is longer than necessary so that the fork can accommodate as many setups as possible. It’s up to the user to cut the steerer to the desired length. Consequently, the 1 ⅛” part of the steerer has to be much longer than the tapered section.
1.5″ Bottom
The lower part of tapered forks spreads. At the widest, the tapered steerer has a 1.5″ diameter.
The entire tapered section is usually 86mm/3.38in.
The length of the taper isn’t a strict number because it doesn’t affect the compatibility of the fork as long as it ends far before the top cup of the headset. Hence this measurement varies across brands.
Some Issues
A tapered fork may end up being too big when installed on a very small frame with a short head tube. In that case, the fork is unusable with that particular frame.
Tips:
- Measure the head tube and compare its length to the tapered-to-non-tapered distance of the fork. If the head tube is longer than the distance, the frame can accommodate the fork.
1 1/8″ x 1 1/4″ Tapered Forks
A less common tapered size is 1 1/8″ x 1 1/4″. Those dimensions are found mainly on carbon road forks.
Since the number of 1 1/8″ x 1 1/4″ forks is scarce, the associated frames are a less than ideal long-term investment.
Other Fork Sizes
Below you will find a list of the most common fork sizes:
- 1″ Threaded Forks

1-inch threaded forks are found on older bikes (e.g., retro MTBs). As the name suggests, the fork steerer is 1 inch in diameter and is secured via a headset that threads on it.
- 1 1/8″ Threaded Forks

Like the 1″ threaded standard, this is an old size. The only difference is that the steerer has a larger diameter and is therefore considered “oversized” compared to 1″ models.
- 1 1/8″ Threadless Forks
Currently, this is the most common fork steerer on the market. Unlike the threaded models, it comes without threads and is secured to the frame by the stem.
- 1 1/8″ to 1.5″ Tapered
The most common tapered fork size.
- 1.5″ Threadless Forks
Forks with 1.5″ steerer from top to bottom. The benefit is that the fork is extra stiff. That said, such forks are rare and limit the rider’s choices.
Additional Info
A tapered fork can be installed on a non-tapered frame with the help of an adapter that positions the low headset cup outside of the headtube.
This conversion allows you to combine a newer tapered fork of higher quality with an older frame.
The downside is that the geometry of the bicycle is altered by approximately 1-degree due to the raised front end.
A non-tapered fork with a 1 1/8″ steerer from top to bottom can be installed on a tapered frame with the help of a reducer headset adapter which fills the gap that such a fork would otherwise leave.
The pro of this conversion is that you can buy a tapered frame and thus secure an upgrade path to a higher-end fork while running a cheaper straight fork in the meantime.
Until next time,
Rookie
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