Can I put a longer fork on my frame?

supersonicsupersonic Posts: 82,708 Lives Here
edited November 2012 in Tech FAQs
If you are thinking about putting a longer travel fork on your frame, there are a few things you should consider. First off: why do you want a longer travel fork? Be wary of turning your bike into a harder hitting machine if the parts and intended usage of the bike do not warrant it.

If a longer travel fork still floats your boat, consider the frame warranty. Many warranties have explicit conditions regarding travel: go too high and you may invalidate the terms. A longer fork will put more stress on the frame, stress that it maybe was not designed to handle, especially if you are going to ride it even harder.

Still thinking about it? Not all forks of the same travel are actually the same length. The crown to axle length of the fork varies significantly. Increase this figure by an inch, and you will slacken the head and seat angles off by about one degree, plus raise the bottom bracket as well as slightly increasing the wheelbase. This will have an effect on the handling of the bike, and will seat you further behind the bottom bracket.

It can be tempting to get a fork with the same overall length, but with more travel. But consider what happens at full travel - the bike will be steeper than the previous unit, and this could make the bike feel more twitchy and less stable in near bottom out considerations. Riding down multiple steps for instance can feel markedly different.

Most frames are usually good for changes of +/- 20mm of fork length/travel, but again check the warranty, and think carefully about what you want to gain.
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