Andy_K 

Do you want the short answer or the long answer?

The short answer: If you can find a 2010 Kona Jake take it for a ride. It'll cost more than the Muirwoods 29er, but I love this bike. In general, I really like cyclocross bikes. My Jake weighs about 7 pounds less than my Muirwoods 29er did, but the difference in feel is significant (and probably not wholly due to weight). If you test ride one, it'll have knobby tires which will make it feel a little sluggish on pavement, so adjust your expectations (or better yet see if the shop will swap on some slicks). If you don't want drop bars, see the long answer.

The long answer: The number of factors that can lead to one bike feeling quicker than another is mind boggling. I'll try to explore that a little here to suggest how you might find an alternative more to your liking than the Muirwoods. Note well, however, that I'm talking about a bike feeling quicker. Objectively, I could get my Muirwoods 29er to put out average speeds pretty close to what I got with my CX bikes, given similar tires choices. However, I often felt like I was working harder with the Muirwoods to get those speeds. At the end of the day, performance is all about the engine, but on the road some bikes will make you happier than others.

The main factors that influence how a bike feels are: the tires, aerodynamics, the frame geometry, the weight of the tires and wheels, the frame construction, and the weight of the bike -- probably in that order.

Tires can make a huge difference in the feel of a bike, but there's always a trade-off. Puncture resistant tires generally have increased rolling resistence and feel hard on the road. Wider tires make the ride more comfortable and improve puncture resistence, but they are usually heavy and if run at low pressure for comfort they have higher rolling resistence. At high speeds or in high winds, the increased aerodynamic drag of a really wide tire also comes into play. Supple tires that feel nice on the road don't last as long as less supple tires, though they often have better grip. As I said before, I didn't like the stock tires on the Muirwoods. I used it with tires as narrow as 28mm and as wide as 50mm. My favorite tires on this bike were 700x50 Schwalbe Marathon Supremes. However, for purposes of the current discussion, let me say that I had a pair of 700x28 Panaracer Ribmos that I used on both my Kona Jake and my Muirwoods 29er, and the Muirwoods 29er felt more sluggish with the same tires. So while I think tire choice is the biggest single factor in ride feel, it's one that's under your control and I don't think it's what I didn't like about the feel of this bike.

Next we have aerodynamics. The Muirwoods 29er generally seems to be intended for a very upright riding position. This is good for comfort, but bad for performance, especially when you're riding into the wind. You can make some adjustments to aerodynamics, but if you want a fast bike, it's good to have a more aerodynamic starting position. Again, there is a trade-off here of speed versus comfort. A properly fitting aerodynamic bike can actually be quite comfortable (and I would argue is more comfortable than an upright bike for trips over 10 miles), but for short rides, it's hard to beat the comfort of an upright position. Drop bars give you multiple riding positions so you can get more aerodynamic when you want to and sit up a bit when you want to. With flat bars, you can get an aerodynamic riding position if the bike is built to allow it. The Muirwoods 29er is not. Even with drop bars and a level stem, I always felt like I was sitting up pretty high. This was definitely a big factor in my discontent with the feel of this bike.

So obviously aerodynamics is largely a product of frame geometry, but the geometry influences more than that. I never quite figured out the geometry of the Muirwoods 29er. It has a long wheelbase and long chainstays, which gives it a stable ride but also means it turns less responsively. The head tube and seat tube are relatively tight (especially on the small size, which I had), which should make the bike feel more nimble and have good power transfer, but it never felt that way to me, probably because of the long chain stays. Again with tradeoffs, the long chainstays are good for carrying a pannier, espically if you have big feet, though I feel like these are still longer than they needed to be.

The wheels on this bike are definitely on the heavy side, but it's hard to get around this with disc brakes. I'm not sure how much of a factor this was for me. I'm still using the front wheel I built for my Muirwoods with a disc brake on my Kona Jake, though I've got a lighter wheel with a rim brake in the rear. I can definitely tell you that I felt the difference when I switched to lighter tires. A lot of the weight on a disc wheel is at the hub, so the actual wheel weight might not be a huge factor in this case.

Frame construction is a complicated art. If you've ever read a bike review in Bicyling magazine you've likely seen the phrase "laterally stiff but vertically compliant." The Muirwoods 29er is definitely vertically compliant (that is, it absorbs irregularities in the road surface). I don't think it's particularly stiff. There's some controversy about just how big a deal stiffness is. Here's what it means...when you stomp on the pedals of a really stiff bike it responds immediately, but when you stomp on the pedals of a not-so-stiff bike it feels like it compresses a bit. In theory, bike frames are very efficient elastically and the compression that you feel isn't actually lost but rather eventually makes it's way to the wheels. In practice, it makes the bike feel sluggish. There's really no way to tell how stiff a bike will be without riding it. Aluminum bikes tend to be stiffer, but I think that's mainly because designers choose steel when they want to make a bike with a softer ride. It's possible to make a squishy aluminum bike or a stiff steel bike. You really need to test ride to figure this one out.

Lastly, we have the weight of the bike. You can go to the Rivendell website and read about how much this doesn't matter. That's completely true unless you're going up hill. If you're going down hill, a heavier bike will actually be faster. If you're coasting it has no effect. When you're climbing a hill, every pound counts. You may be tempted to think that as a 240 pound rider five pounds here or there doesn't make a difference. In fact, it does. (The 25 pounds of crap in your pannier matters too, of course.) This was the thing that killed my relationship with my Muirwoods. For three years, I was mostly happy with it, but then I moved to the top of a hill that climbs as much as 20% in places for a quarter mile. The difference in riding my lighter bikes up that hill convinced me to ditch the Muirwoods.

There is another way that bike weight makes a difference in the feel of a bike, however. A lighter bike feels different underneath of you as you ride it. It moves more freely. It goes where you want it to. As long as you're using a rack and panniers, you probably won't experience this, but for me it's a big deal.

I should also mention, btw, that the above is intended as an analysis of the little niggling discontent that eventually convinced me to sell my Muirwoods 29er and probably comes across more critical than it should. If you read the other thread I linked to, you'll see that I generally did like it. I just liked my other bikes more.