Now that's what I call a new take on geometry....

2manyoranges

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Ra bikes are interesting....nice article in Cranked #15 a few years ago on the birth of Ra bikes (Rafi Richardson)...now they are getting mature. And shaking things up quite a bit...such as....look at the height of the bottom bracket on this:


4477a4_20c3933dfca0469ab344c9edee3a8b81~mv2_d_4746_3164_s_4_2.jpg


And read the really radical take on sag and reach - I always have advocated at least 30% sag, even in short travel bikes. But boy, Ra goes with 40......gosh...and here's the interesting rationale...

 

mk one

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I suppose you can get away with lower bb's resulting in lower centre of gravity on bigger wheeled bikes, wouldnt be practical on a normal sized wheel though. Looks planted.

And depending on the bike i used to run 35/40% sag on my dh bikes, used to help with holes and dips, allowed the wheel to move freeer in both directions, works better with a linear rate than progressive though.
 

2manyoranges

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Mk1 that’s exactly right right travel. So many people run their forks too hard, aiming for maximum travel. But now with tokens and the extreme adjustability of forks and shocks, you can really tune performance - but you need to be understanding exactly what principles should be used for the tuning - and allowing the suspension to drop into holes and dips is essential for actually having a suspended main mass....

You’re right re planted...that’s exactly what I thought when I saw it. One feature of my 29ers is the teetering feel of the hardtails - caused by big wheels and ‘normal’ BB relation to axle axis through the bike. A radically lower BB like this is very interesting. I’ve not ridden one but will try to....
 
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FluffyChicken

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40% sag is nothing new, just ask anyone with old forks.
Elastomers do that automatically over time or when you're a bit fatter that 'medium' and people can never be arse to put air into fork until they're flat.

100% sag is also often seen.
;-)
 

novocaine

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whilst I do appreciate a modern geometry when done well (in this instance I'd say it's pretty well done) I sort of think they look broken. The steeper seat tube and slacker head tube always make the bike look like it's been bent in the middle. This is even more pronounced with the S style down tube.

I'd say that Rafi has this pretty damn close to spot on, both in terms of pushing some of the modern boundaries of geometry and, thanks to the fairly lax seat tube, classic look of a nice bike, and all thanks to the bend in the tube at the BB. Helps that I've always had a thing for a straight line from back wheel to head tube on the top tube/seat stay line.
 

2manyoranges

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Interesting Novocaine - for me, having messed with geometry for the past decade, it’s the reverse. In the Ra above I see the symmetry of the angle of the seat tube and forks, and on all new geo bikes I like the ‘wheel out in front of me’ - so much so that any retrobike (69-72 head angle) looks as though the bike has been front-ended and the forks bent backwards under the bike. We covered ‘wandering front end’ in other threads, and that problem is all but nonexistent now, with 63 head angles, 35mm stems and short offset forks.

As you say, the ‘straight line through the back axle to head tube‘ is emerging as a nice common feature: Stanton, Cotic, Bird, Ragley.
 

novocaine

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I don't think I've made myself very clear, I like this one. :)
Its geometry like the bike below i think looks broken. I think it's that the extended triangle made by the fork and seattube angles moves to being in front of the back wheel rather than somewhere over the back axle. Very steep seat tube because of the short chain stay and to keep a decent bb to seat ratio for decent climbing. Don't get me wrong, I'm sure it rides fantastic and looks don't really matter, it just hurts my head a little bit. (best image I could find in a rush)
Screenshot_20211021-105721.jpg
 

FluffyChicken

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just looking at the green 410 above and all I can think is there would be nothing left of the back of the seat tube up hear, it would be worn down by the thick mud and gravel picked up while riding and probably clog up quicker than even a retrobike with a top-swing mount front mech and stay brace. There would certainly be no paint left on the bike there.
 

2manyoranges

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Blimey…FluffyC that’s a 2cm gap…just trying to imagine where you ride..it sounds like the trenches in 1915….


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