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I am very curious about the geometries of mountain bikes nowadays (or probably since a while back).

They all seem to have very tilted top tube .. compare my Kona Blast 2001 vs 2019


Kona Blast 2001 Kona Blast 2001


Kona Blast 2019

Kona Blast 2019

For the newer bike that fits well when riding .. have tendency to be hitting my crouch when I dismount somehow.

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    From looking at those pictures, it looks like they raised the head tube and lowered the top of the seat tube. The head tube change (and other changes up there) is probably to get a longer travel on the shocks, but may also help with fitting fatter tires. The seat tube/post changes make it possible to fit this size of bike to a wider range of people. – freiheit Feb 28 at 0:07
  • See how much better the old one looks! Apart from perhaps disk brakes, every other change is driven by fashion rather than reason. No reason for upgrade! – Zeus Mar 4 at 6:49
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Circa 2000 a Blast had 80mm travel and 26" wheels on 1.90" tires, compared to a modern Blast -27.5" wheels, 100mm travel, on 2.25" tires. The crown height on the modern Blast is significantly higher than its ancestors, necessarily raising the top tube height at the front.

The seat tube with modern geometry has been shortened. Among other things such as handling changes, it helps with stand over height allowing a broader range of riders to fit the same frame.

  • Nice .. thanks for the snippet .. I didn't even know the travel for my bike's shock even after so many years! haha – Edmund Fong Feb 28 at 16:16
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The current trend with mountain bikes is that consumers are beginning to see having the ability to run droppers in the 175-185mm range as the baseline and a required feature, not an extreme. Seat tubes are getting shorter and top tubes are getting more sloped to make this possible. Another side to it or way of thinking about it is that everyone wants to buy and sell aftermarket droppers now, but people have proved largely incapable of doing the math to figure out how much travel they can run for their saddle height before buying, which incentivizes companies to just push it to the max up front in their frame designs.

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