So there’s a great discussion regarding what defines “all-mountain” over on V-Salon. I’ve been adding some thoughts but figured I’d expand more in depth over here at 44HQ. Like I mentioned on V-Salon, a lot of what I build I suppose could be put into the all-mountain hardtail category. But to me, this definition is a bit redundant as it relates to mountain bikes. I build my bikes to climb equally well as they descend and perform in tech every where between. Basically I want me bikes to rip the whole mountain. So if that’s “all-mountain”, so be it. But to me, that’s exactly what mountain bikes are all about.

I believe I took my front derailleur off sometime around 1995 or 1996 and have been running a 1x setup ever since. For my own sensibilities, there was just too many gears I found I was not using and if I couldn’t pull the climb with what little I had, walking was ok as it was motivation to try harder next go. I also rode a lot of BMX street as a kid, and when mountain bikes hit the scene, I just wanted to translate that same kind of play on the streets to the trails. So my own setups have been more about being able to play out on the trail while I’m riding than anything to do with racing. (Even though in my head I’d pit myself against all the greats in an epic battle to get back home aka ‘the finish line’.) So the bikes I build today are more of that evolution I suppose. If that’s “all mountain” with “short stays” than so be it. What I’m building and the numbers, angles and lengths I’m building around reflect what type of ride I’m attempting to deliver. And that’s what it’s all about kids. The ride. Below is an image of the very first 29er I built with Ted Wojcik. 17″ chainstays, 69 degree HT Angle, 73 degree Seat Tube angle, BB height was 12.5″. This was my starting point.

IMG_6548

So this past summer I had built up a test rig to start to have an informed opinion on chainstay length, wheelbase and what happens when those are changed if all other aspects remain a constant. So if I length chainstays, subsequently lengthen wheelbase but keep the rider compartment intact, what happens on trail? And vise-versa: shorten the chainstays, subsequently shorten the wheelbase but keep everything else intact? This post starts to touch on initial findings. I wanted to follow up on some additional on trail input after riding that bike in different configurations and subsequently building a few more 29er mountain bikes using that input. Below is the second prototype I built sometime around 2009. It sported a 70.5 Degree Head Angle, 73 Degree Seat Tube angle, 16.75″ chainstay length and 12.375″ bb height. This further evolved what I was looking for: A bike that climbs well, rips the DH runs, easy to loft the front end and plays well with everything in between. This was a game changer for my own evolution:

Black and Blue

Having ridden the above for close to 2 seasons, I was ready to make some changes and further evolve the design. These changes were passed along to a wonderful client in North Carolina. His bike is below which sports a 70.5 degree head angle, 73 degree seat tube angle, 12.25″ bottom bracket height and 16.5″ chainstay length:

Yuri's 29" Complete

If you’ve been reading up to this point and not just looking at the pictures, you’ll start to notice some constants forming while other pieces of the puzzle are changing incrementally. I feel I started a bit too slack in terms of Head Angle. I noticed in tech where you have to go up and over something as you crested the obstacle and weight was shifted back, the front wheel wanted to flop to the left or right. Slow speed tech seemed a bit sluggish as well but the wheel flop was happening frequently enough fot make me reconsider. Steepening the head angle a bit helped this, but also increased the quickness of the handling which I liked. Keep in mind these are all numbers with 20-25% sag built in. As i adjusted head angle, I began to sink the bottom bracket height a bit, putting the riders center of gravity a bit lower. This helped to quicken steering as well, but also to ground the bike a bit more at speed. As I dropped the bottom bracket height, I also have been slowly shortening the chainstays. Why? Because I’ve not only been experimenting with where that magic spot is in terms of balance of play vs balance of climbing and descending, but also I have been slowly honing my technique for forming chainstays, dimpling and bending the tubes all the while checking clearances and different setups. So as my technique has been progressing, so has the geometry and numbers at play. These aren’t numbers I’m pulling out of the air either. These are informed decisions based on lots of riding and lots of different terrain. Which brings me to this build:

Flat Black Sickness

You’ll notice that it’s nothing too special: Traditional hardtail look and feel. However, it was necessary to push all the previous iterations in order to get to this spot and inject all those attributes and small details into a traditional style hardtail. A New England hardtail at that too. I’ve deeply formed the chainstays in both the horizontal and vertical planes. One lends itself to massive tire clearance, while the other helps to stiffen the stays laterally. I’ve created a true radius seat tube so the rear wheel can be tucked under the rider just a bit more. But that’s a 73 degree seat tube angle and I’ve built around that setback post. I’ve placed the rider center of gravity “just so” between the wheels to achieve a good balance for both climbing AND descending. I’ve had numbers of riders comment how they can’t believe how far off the back end of the bike they can get while descending. And then in the same breath say “But this bike climbs too!” And that’s the special sauce as I like to say. It’s that balance. So now how does this whole recipe start to evolve out on the trail when I’m changing up the stay lengths and lengthening/shortening wheelbase?

16.75″: Good overall feel but just a bit on the long side for my taste. Quick to pick up and go, but it still requires some effort.

16.5″: This was an eye opener for me. The front wheel pops up no problem. You’re still “in” the bike, ripping turns, climbing well and keeping things under control.

16.25″: The bike becomes playful. 26″ feel starts to creep in. Given that it’s full rigid, I’m starting to feel some chop and chatter I come into tech at speed. Again, still climbing just fine, front end stays planted and descends like a champ. But that playfulness of the 26″ feel has my attention.

16″: Full on pop. The rear wheel is over the obstacle before you know it. I was finding myself carrying too much speed in corners and not being ready for that rear wheel to follow my path so quickly. I had to make some adjustments in “english”. The bike is incredibly playful and rips up and over things with ease. Still climbing easily. Negative attribute seems that the high speed tech is a bit choppy due to the shortening of the wheelbase. I begin to wonder if a suspension fork will help to quiet this. Which leads me to THIS build:

Kid Dangerous

16.25″ chainstay length, 12.25″ bb height, 70.5 degree head angle, 73 degree seat angle. Remember that chop at speed I was speaking of above? Gone with that 120mm Fox fork. I have that playfulness I was looking for. I chose 16.25″ for this reason: I wanted to see if I could balance that great all around feel of 16.5″ which I had a feeling was almost right with that “woah” feeling of 16″. This bike climbs, descends and does everything in between either at speed or at slow speed. I also lengthened my personal rider compartment a tad with this build too shifting my weight just a tad forward and down. Ultimately, I look to put the bars and saddle at the same height when I do the drawing. Almost all of these builds share that. Based on all of the above (Which is a build journey stretching from 2008-2013) I feel like I can start to make some informed comments:

If someone asked me that they wanted a bike that descends as well as it climbs but wants that pop, I’d most likely recommend in the 16.5″ chainstay length area. Good tire clearance, playfulness is still there but long days don’t chop you up. If someone wants more injection of playfulness, I’d recommend that they roll closer to 16.25 or 16″ but know that some compromises in handling at speed in tech will show themselves with some chatter or chop since the wheelbase is shortened. Longer days or more “race” feel with a 1x setup still at the forefront, I’d send them more in the 16.75 range. Still has pop mind for the race minded chap, this may be a good way to go. 17 or 17.5″ and that front end feel a bit heavy and lacks that pop I’ve been talking about above. It should be noted that I’m building around 1×9, 1×10 and 1×11 speed setups too. I feel there is a lot of spread especially with the newer 36t cogsets.

But after all, these are just numbers. It’s the combination of all these factors: Head Angle, Bottom bracket Height, Positioning of the riders center of gravity, and chainstay length that makes the magic happen.