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So I've a Stumpjumper 2019/20 bike (size large..)...
It's brill.. does everyhting a trail bike should.
Having looked at the new EVO with it's 63.5 degree head angle etc and adjustable geometry, it got me thinking..
My stumpy has the flip chip - you can basically offset the shock mount by 5mm for/aft, so in 'high' you have a 0.5degree steeper head angle and a 6mm higher BB. And obvs in 'low' it's a bit slacker, with a lower BB..
Looking at the geo charts, it seems the NORMAL stumpy has a 33mm BB drop, and a 342mm BB height.
The EVO has a 37mm BB drop, which in it's slackest can go to 44mm drop (I predict pedal strikes!!).
Now....
bear with me...
I'm currently running my Stumpy with 160mm forks, so the front is 10mm higher ANYWAY, this the BB height will be a few mm more than stock, and it'll be a 'bit of a degree' slacker. And I run it in the 'low' flip chip setting all the time...
"What's your point DrP...?"
Anyway... My point is for fourteen quid I've ordered an offset bearing for the UPPER shock mount, which will drop the BB by 5mm (38mm drop), and slacken the HA by another 0.5 degrees..
So I've essentially got 4 geo settings now...
with/without offset bushing, and high/low flip chip.
What I'll do is fit the offset bushing and leave that, and then (hopefully) flipping the flip chip to 'high' will in fact be the OLD 'low' setting... and then having it in 'low' will be even lower.... ALMOST like the new evo, but without the super slack HA...
The flip chip is easy to flip over..bushings less so, hence why I'll fit and forget the offset.
Anyway...
My point is I can't leave things as they are, and like to fiddle, and will be interesting to see what the slacker/lower bike is like for enduro/bike park riding, whist keeping the ability to 'raise it up again' for normal trail riding..
I'll feed back. I guess....
(this is where if I were a bike manufacturer, I'd have a gif with teh varying geometry on it...)
DrP
Interested in hearing how you get on with this. I've got the 27.5 Stumpjumper, 150mm forks and have been considering an upgrade from Rhythm 34's to a 160mm 36 or Pike, Lyric etc.
Hoping to raise the bb a little as I get so many pedal strikes, even with the flipchip in the high position. Working on my pedalling technique also!
My local riding is natural trails, rocky and fairly technical so tweaking the front end may prove beneficial!
Also following.
Im running my stumpy with 160mm pikes and its perfect. Ive also spoken to 9point8 about a slackr (the current one doesnt work) and they are working on it.
However when i bought this bike i was running a mullet bike with a 63.5 ish head angle. this was great downhill (although the 26" rear was the main benefit) but it made everything else boring. I specifically bought this bike because it was more fun and i think the steeper HA has a lot to do with that. I also think that you have to be careful with the seat angle as youll find it a pain up steep stuff
andybrad - What fork offset are your Pikes? There's a fair few options so wondering what would suit mine.
I recently added a -2 degree slackset to my Cotic Flaremax.
The bike is built for 120-140 forks and 'recommended' at 130. I run mine with 140's and the original geo with 140 forks is:
- head angle 65.1
- seat angle 73.1
- BB drop -27mm (which I think works out at 350mm?)
Ridden it twice now, on steep Tweed Valley trails and it's a keeper. More stable and no less hard for climbing. No idea about pedally singletrack, as we have very little and as the bike was also designed to run 27+ I think the BB was slightly higher than needed.
I did extend the stem from 35mm to 45mm, to get some reach back.
I Suppose the only thing with the new Stumpy Evo is that it varies geo by letting you adjust the upper headset cup directly to change Head angle and by extending/shortening the chainstay (at the horst link position) to affect the BB drop.
All of which I presume is indented to minimise the changes to the Front centre/Reach and seat angle?
While the combo of offset bush/Yoke Flip chip and changing fork length all work to slacken/lower the bike, they do so by effectively tilting the front triangle back a bit which of course changes reach and seat angle along with the head angle and BB drop, not that these will be huge changes but you might want to tweak the saddle position for pedalling a wee bit if you end up leaving it in the most slackened/lowered mode?
Plus Will you really bother flipping the flip chip between rides?
I mean as wonderful as having little geometry adjustments available is, I bet most people just treat them as set and forget after a couple of weeks...