Remember that wild Chromag hardtail that debuted a few days ago? You know, the one with the chopper-esque head angle that makes most downhill sleds look dated? While the Doctahawk is built by Chromag, the long and slack geometry that sets it apart was conceived by Clark Lewis, a Whistler local known for his prowess on a hardtail. The concept and benefits of longer, more relaxed geometry have been covered many times, but things change a bit when you start to apply those same principles to a hardtail.
Below, Clark explains the reasoning behind his namesake's geometry.
My name is Clark Lewis, and I'm an emergency physician who has been riding hardtails with the Chromag crew in the Whistler area for fifteen years. I designed the geometry of the new 'Doctahawk', which is a PC version of my well-earned nickname, Doc Tomahawk. I've been riding it since last spring, alongside two other Chromag riders on similar frames, in the gnarly, steep, rough, janky, and awkward terrain that it was designed for.
There seemed to be a lot of interest and misconception around the Doctahawk's geometry (shown below) which I wanted to address here.
Keep in mind the difference in "dynamic" geometry between a hardtail and full suspension bike. I'd argue that I'm not far from the equivalent modern slacker/longer full-suspension rig. Only the front sags on a hardtail, so when you're riding, both the SA and HA are steeper than their static numbers; much steeper descending in steep terrain, but the rear can't sag while climbing.
On a full-suspension bike, where the rear sags a bit more than front, both SA and HA get slightly slacker on flat terrain, slightly steeper descending, and often much slacker climbing. Consequently, to get similar dynamic ride geometries, a hardtail can get away with a slacker SA, but needs a much slacker HA.
In other words, the Doctahawk's 77° SA and 62° HA have a similar dynamic feel to me as the Pole Machine
(79° SA, 64 HA°), which I rode briefly last summer and liked very much. It's quite different to my friend's Nicolai Geometron
which was set up with 77° SA and 61° HA (I wished for a steeper SA, but found the HA simply ridiculous, at times laugh-out-loud entertaining, but just a handful at other times).
Also, remember that the dynamic feel of any bike is a result of the overall geometry, plus many other factors (tires, suspension setup, stem length, 'bar width, ride style, etc). Two bikes with disparate geometry can have a similar dynamic feel, while others with similar geometry can feel very different. The static numbers are just a part of it.
My Climbing Theories
1. Steep STA and long reach will keep me in a more powerful pedaling position and mitigate front wheel lift on steep climbs.
2. "Cockpit length", aka effective top tube length, will feel "normal" despite the long reach because the steep STA brings my bum closer to my hands when seated.
3. Chainstay length is a negligible factor in hardtail climbing performance (longer stays are more important for full-suspension climbing, but that's off-topic).
4. The new Lyrik 180 is only slightly taller than the old 160, so I should be able to run it with slightly more sag to achieve the same dynamic ride height (ie. bar height when you're on the bike sagging the fork).
5. A shorter offset fork may help mitigate front wheel wander on steep climbs with such a slack HA.
6. Long wheelbase will require more dynamic input to get around tight switchbacks.
This bike climbs ridiculously steep terrain with zero front wheel lift, even with a 180mm fork. I don't feel "stretched out," even with the extra 50mm reach (compared to my previous bike), because my bum is more forward. I planned to run a short stem, but after trying stem length from 10-60mm, I settled on 50mm to increase front wheel pressure for cornering in mellow terrain.
Interestingly, there was no difference in climbing performance between the two versions of the frame with a 20mm difference is chainstay length (I spent half of last year on each frame, and preferred the longer CS version mainly for descending). The shorter offset fork did quiet down the front wheel wander, but I didn't find the longer offset fork troublesome, even with the front wheel so bloody far out front. We have plenty of awkward tight switchbacks that were easily managed with wide steering and the odd front wheel "lifty" for really tight corners.
One negative; there's a bit more hand pressure on long mellow climbs or flat terrain, but I got used to that, especially after switching to a higher rise bar.
My Descending Theories
1. I want a shorter ST length to leave room for a 170-200mm dropper post to get the saddle completely out of the way for very steep terrain.
2. Longer reach shifts my weight forward, moving weight off the rear wheel which is helpful for increased comfort on a hardtail in rough terrain.
3. I want as much travel as possible up front to make "riding the fork" while descending more comfortable. The extra mid-stroke support of the new Lyrik will allow for this without excessive diving.
4. I want a much slacker HA to feel comfortable riding in that more aggressive forward attack position without fear of going over the bars, especially with all that travel to cycle through.
5. The long wheelbase will help keep the bike calmer in fast rough terrain.
6. Front and rear center "imbalance" is less troublesome in real life than it is for some people on the interwebz, as is the imagined "problem" of disparate front and rear travel (if you ride both hardtails and squishy bikes you know this is silly. They really don't feel that different, and the hardtail just needs more energy/input/finesse).
7. Longer reach may make wheelie's more difficult, but I can mitigate that with good technique and relatively short chainstays.
This bike is a monster truck on descents, and it's far more comfortable at speed and in rough terrain than my previous hardtails. To get the most out of it, I ended up running DH casing Minion DHF 2.5'' tires front and back all summer and just dealing with the extra weight while climbing. The rear end requires less energy to control with my weight more over the front. Evidence of this came in the form of final tire pressures - I ended up at a nearly-balanced 22psi front/23 psi rear, instead of my previous 20/30; a big difference in comfort and traction. The new Lyrik damper stands tall in steep terrain. I went over the bars zero times; it never even felt close. Wheelie's were slightly harder, but I got used to it quickly.
On the negative side, the bike MUST be ridden aggressively and with a lot of pressure on the front wheel, otherwise it'll just run away on you and you'll lose traction. There were some scary moments early on where I got lazy and "sat back" to try to rest... Bad idea. The trails I prefer riding generally demand your full attention anyway, and I'm a trail "smasher" at heart, so this is fine with me. Consequently, there is more demand on your upper body, so do some extra push-ups.
The only thing I'd change is perhaps a taller head tube (more than one inch of under stem spacers is ugly), and this spring I'll try an Angleset to see what 60 to 61-degrees feels like... Because why not? 62 feels "just right", but who's to say that the limit isn't a bit further.