New bikes, steeper seattubes, inline posts.....

[GrahamJohnWallace]

So what you are saying is, they are moving back to retro seat angles and retro inline posts? (of course back then it varied with frame size, at least on decent bikes).
(for example my 92/3 ish Rockies).
Nowt wrong with that, good to see they've seen the light.

I too have a certain degree of nostalgia for the long slack geometry of the early mountain bikes. However that was a geometry copied from the 1930's fat tyred post-boy bikes that the US MTB pioneers used to make their 'clunkers'. It was not arrived at as a result of science, experimentation or testing. It was the geometry that the pioneers were used to riding and happy with and probably came from the 1930's road motorcycles that the original post-boy bikes were intended to emulate.

Joe Breeze, Charlie Cunningham, Tom Ritchey and others, did however play around with handlebar and stem designs. This was probably influenced by their road riding backgrounds and the more forward riding positions they were used to.

 

[brocklanders023]

Re:

No idea about the witchcraft that is bike geometry but I do know my modern full suss and hard tail, both of which have slack fronts, 50mm stems, 780mm+ bars, loooong wheelbase and looooong top tubes and low bottom brackets feel ace to ride but make retro bikes feel incredibly odd.

 

[mattr]

Re: Re:

Correct me if I am wrong, I probably am, and feel sure that you will, but:

*isn't bio-mechanics concerned with getting the best possible power output from the human body, and the influence of riding position is well understood and does not change with fashion?

Sort of. But the best position for power isn't always the best for weight distribution, aerodynamics or handling. So moving up and forwards improved some aspects off road, when combined with the front end changes. If you want to do it on road you need to rotate around the bottom bracket to maintain (or improve) aero. Have a look at Adam Hansens position of you want to see an extreme example.

*aren't very slack steering angles to do with avoiding unstably steep steering angles resulting when the front end dives on long travel front suspension bikes during heavy braking? (With anti-dive front suspension systems we wouldn't need such steep angles and the long wheelbase that goes with them.)

they aren't *very* slack. Just around the 69-70 degree mark. 10 years ago an XC race bike would be around the 72 mark. Slack these days is more like 66 ish IIRC.

*that according to the physics of inverted pendulums, (ie the physics of how top heavy things balance) the bicycle is a form of inverse pendulum that falls sideways more slowly the taller and top heavy it is? (Therefore, with lower bikes you have less time to regain balance when it is lost)
https://en.wikipedia.org/wiki/Bicycle_a ... e_dynamics

*that lower bottom bracket heights increase the chance of pedal grounding and mean the pedaling cannot be maintained through corners, inverse cambers etc?

bottom bracket isn't particularly lower. The seattube getting steeper also (slightly) increases the height of the CoG.

*that increasing the weight over the front wheel also increases the risk of that wheel skidding in slippy conditions? (far better if the rear wheel slides as it is much easier to control)

it's more about weight distribution front to rear. I doubt the net effect changes that much. Too little weight is also less than ideal......

*that long rear ends result in less weight over the rear wheel, less traction and so poorer hill climbing ability?

https://en.wikipedia.org/wiki/Bicycle_a ... e_dynamics

chainstay length for xc race bikes hasn't changed significantly.

One thing to bear in mind is its a complex system. Push down in one place and you might not get the bits coming up that you expect.......