Originally Posted by Peek the Geek
- Since my current fork has 80mm of travel, do I need to stick with an 80mm fork since that's what the frame is designed for? If so, that limits my choices by a lot.
The rule of thumb that gets thrown around here a lot is not to increase your fork travel by more than 20mm.
The critical number, however, is not the fork travel, but instead the axle to crown height - this is what affects your bike geometry (most significantly, the effective head angle), and therefore your bike's handling characteristics, which are the real concern here. The relationship between fork travel and axle to crown height is typically linear, but not always - for example, my old 05 Marzocchi 66R has 150 mm of travel and my 06 has 170mm,
but the 06 66RC2X is actually
shorter A to C than the 05. So I gained about an inch of travel while actually dropping the front of the bike the same amount.
Axle to crown heights can be harder to dig up, but depending on your choice of fork, you can add travel and still retain or tune your current geometry to your liking.