Tony, a fellow STR member, sent me this message the other day...so I'm going to answer him. Here goes...Tony's message is in italics. My answers follow.
(disclaimer: By the way, let me say that I am not an expert in the physics/mechanics of bicycles. I only know what it feels like to me when I ride. So, this answer isn't going to be all technical with discussions of angles of tire incidence, tire contact patches, and the like. Hope it helps anyone who wants to know about 29ers or trail bikes.)
This is Tony, I met you on the camping trip. Now that you have spent ample time on your Niner, and especially now that you have ridden both that and your Yeti at Hurkey Creek I have a request. This could even be an interesting blog update for you.
So far, so good...factual.
I would like to know your opinions on the strengths and weakness of the handling and performance between your Niner and 575. Which bike is a better climber for moderately technical climbs like Keen climb?
Keep in mind that comparing the Niner with the 575 is difficult because one is a hardtail while one is a long-ish travel full suspension bike. HTs, by nature, will outperform some aspects of FS bikes (ex: climbing), for example.
However, I can say that it was much easier for me to climb Keen Camp on the Niner. The larger tires roll over obstacles in a much smoother manner. I know everyone says that, but I have found it to be true for me. Also, the Niner is a HT...that helped A LOT! The Yeti is also a lot heavier than the Niner by at least 5 lbs. That doesn't sound like enough to make a difference on the climbs, but I can tell.
Which bike gives you more confidence in sandy rutted twisty descents like Exfoliator?
Hmm...the Yeti wins on this comparison. Having the extra suspension in the rear (I run the Talas 36 on the Yeti almost exclusively in 100mm and the F29 on the Niner is 100mm too...only difference is the through axle on the Talas makes the fork less flexy) makes the ride so plush. I know I can screw something up, and it will still be very forgiving. With that said, I don't think I rode down Exfoliator that much slower. In a race situation, I would rather sacrifice a little bit of descending speed for what I'd make up in the climbs on the HT.
Now, if the descent is really technical (in the rocks, roots, obstacles sense), I think that the Niner holds its own. We recently rode Gabrielino trail in the San Gabes twice in about 1 month's time. First ride was on the Niner. Second ride on the Yeti. I was FAR LESS beat after riding the Yeti. I descended much slower on the Niner...every rock seemed to ping-pong the back of the bike around (which I'm used to since I learned how to ride on a HT). It's just more exhausting. We also didn't do as much climbing as ride #1 (Niner) so I may not have been feeling as worked due to other factors.
Do you notice a difference in acceleration between the 2 wheel sizes, or does the suspension from the 26er negate that?
I am pretty good at pushing a big gear. Too good sometimes. I will often forget to give my legs a break and spin in an easier gear because I am able to ride in a harder one. Often times, this will tire out my legs.
My point is that for a rider who can push a bigger gear, getting up to speed on the Niner seems not to be very difficult. I feel like (again, my opinion) I climb much better on the Niner overall. "Okay", you might say, "but that's because the Niner is a HT." True, but when I raced XC at Fontana a few months ago, I did two races on a HT Stumpy (26" wheels). I cleaned stuff on the Niner that I couldn't on the Stumpy. AND, I rode faster up hills.
Does the added stability of the Niner work against you in moving the bike around the trail at speed?
In my opinion, not at all! In fact, descending a smooth-ish or even semi-rough trail on the Niner is great BECAUSE it is pretty stable. I feel like it tracks better. Therefore, I am smoother and don't need to make as many big adjustments on the descents.
If you had to do last months race (Idyllwild Spring Challenge) again, would you chose the same bike, why?
I would absolutely choose the NINER again! I have raced the Yeti (Keyesville Classic Stage Race) before. It was the best all-around bike for the task (DH, short track, XC)--though if I did it again, I would sacrifice time in the DH and do the race on the Niner. Racing a 29 lb full suspension bike with plush travel sucked. It was hard and quite tiring on the climbs. I bombed the downhills, but lost time on the climbs.
Pure and simple, the Niner is more efficient because of two things: no rear suspension and bigger wheels.
I have been riding 29ers for 2 years and have always had some problems with aspect of their handling, while loving others. I am currently looking to pick up a 575 because I want something more agile that can handle bigger drops than my Leviathan was designed for. You probably don't have the same issues of frame and wheel flex as a heavier rider would, but you have enough experience on those 2 bikes that I think it will be interesting.
What about a JET9? Canzo?
I really love both bikes, given they are applied to the right sorts of trails or races. When I ride the Yeti, I think "this is my favorite bike!" When I ride the Niner, it's the same. If you want something to handle bigger drops and give you a smoother overall ride (able to cruise over obstacles with ease yet not get killed on the climbs like a DH bike would do), then the Yeti is the better option. If you want pedaling efficiency, low weight, and don't mind a rougher ride, I'd say a 29er hardtail fits the bill.
Now, though, those 4-ish" travel 29ers could be the best of both worlds. I hear a lot of people say they can never go back to 26" wheels. Hogwash! Sure you can, but you have to be willing to adjust your riding style and be flexible. I know that each bike, in my case, has distinct advantages and drawbacks. I know, for example, when I ride the Yeti, I have the confidence to hit bigger things, to really tackle the technical trails with ease.
I have found that I was able to clean all but about 3 switchbacks on Holy Jim on the Niner, which was something I couldn't do on the Yeti. The Niner seems to handle switchbacks pretty well. Also, when I raced in Idyllwild, I cleaned a lot of climbs on Lower Southridge that I had to walk up on the Yeti (these included significant technical challenges as well).
This assignment has no deadline, and no maximum or minimum word count. Hopefully, myself and others can get some insight from your experiences.
Well, I hope this has given you some insight! All I can say is that really, there are so many different variables between the Yeti 575 and the Niner AIR9 that could make me think one is better than the other: weight, travel options, application (race vs. fun)! I would borrow someone's Yeti and take it for a ride. Really put it through it's paces...then you'll know if it's right for you!