I used to compete in mountain biking events. However, that was 10 years ago and all my friends who used to do it with me got married and retired. I have another group of friends who like to ride, but they ride road bikes and they effortlessly put on a lot of speed. I have smaller, knobby tires and a lower gear ratio, so it’s difficult for me to keep up with them. However, on the (paved) trails that I ride on, I’ll occasionally see a path not taken, looking to be explored. So, while I’m not exactly looking to do single tracking or log jumping or two foot drops, I do want to explore off-road (occasionally). So, basically, I want to ride as fast as a road bike, but be able to take it off road and not worry about frame damage and flat tires. Any good ideas? So far, I’ve seen the Specialized Sirrus and the Giant Seek 2 (as opposed to 1 or 3). Does anyone have an opinion on either of these? Thanks.
Go for a cyclocross bike, like the Specialized Tricross. You’ll be a at a slight disadvantage on top speed with a 48x34 crankset, but you could always run a 53x39, or get a triple. The gear set up you use depends on how you want to use it. And while you wouldn’t take it off a two foot drop, you can ride a suprising amount of single track, even technical stuff, on a cross bike. You might not beleive it at first, but you have a ton of control in the drops off road, so don’t think that you have to have flat bars.
Have you looked at cyclocross frames? These look just like a road bike, but they have more clearance in the fork and brakes for larger knobby tires. I have a Kona Jake the Snake and with road tires on it it is almost as good as a road bike.
Most bike brands have a cross bike. Specialized calls theirs the Tricross, Giant’s is called a TCX. For a full list, see http://www.roadbikereview.com/latest-bikes/cyclocross-bike/PLS_5670crx.aspx
The bikes you are talking about are commonly referred to as “hybrid” bikes, and tend to have a flat bar, wider tires than road bikes, and are usually a little more low-end than a real road bike, with more weight, cheaper materials and cheaper components. They are more of a commuter-style. You’re not going to keep up with your road biking friends, most like, but you will still hav fun, and your bike won’t be as fragile.
Depending on your price range, you might also look into cyclocross bikes, which have knobbier tires, but the traditional road bike stance, better, lighter frames, and better components.
Hybrid bikes normally run around $500, while cyclocross bikes usually start in the $1000 range.
ETA: I’m too slow. 
It’s been more than a decade since I did any off-road riding, but it sounds to me like you’re looking for a cyclocross bike. Specialized makes a TriCross comp, Trek makes an X 01, and Giant makes a TCX Cyclocross. I’d base my choice on fit and local shop support.
Edit: Upon pressing “Post Quick Reply,” I see that you guys have it under control. By the way, though, if you’re willing to invest in a second set of wheels (or even tires), you can really make the bike feel better suited to pavement or trails pretty quickly.
These kind of bikes provide the worst of both worlds. You’re not going to keep up with your friends on anything but a true road bike, and you’re not going to really feel comfortable and have fun off-road on anything but a true mountain bike, so I would decide which one you want most, buy it, and then save up and buy the other one later. Don’t be afraid to buy used or wait for blow-out sales. You can pretty much be assured to get the bike you want at less than half price if you are patient.
At least around here, as soon as you get off road, even in public parks and such, you’re looking at big rocks, occasional deep sand, pretty bad erosion in some places, loose gravel, cactus, etc etc. You pretty much need suspension and knobby, durable tires if you don’t want to walk home.
A cross bike can handle most of that. For the extreme stuff a mountain bike is better but a cross bike can handle stuff like the 24 hours of Old Pueblo course with no problems. That’s desert, sand, gravel type stuff. Technical twisty decents or babyhead rock fields are out though. Sounds like the OP was looking at dirt paths.
I do agree that a full quiver of bikes is better. I’m down to four bikes now (used to be seven).
Cyclocross bike is the order of the day here, as the others have said. I own the tricross that Dag Otto recommends and it is a great bike. It can be ridden off road on simple trails without any problem - if you get skilled you can take it up and down some very gnarly stuff indeed. I live near probably the biggest mountain biking trail centre in the UK, and take the tricross out on the black route every once in a while. It’s smooth on the road and plenty fast enough - you wouldn’t win a road race on it but you can keep up with your mates nae bother.
As great a bike as the tricross is, mine is currently hobbled with a child seat on the back. It was the only bike I owned drilled for a rack, so no more tearing up the trails on it for me - just pootling along with the wee man on the back. Well worth it 
Babyheads and up (up to boulders) are what I meant by big rocks. I’ve never ridden a cyclocross but I have to admit I’m skeptical until I can try one out for myself. I can think of some trails they would probably work fine on but they would be the minority around here. Add in that I’ve never seen anyone on one here so I figure there’s got to be a reason for that.
What is the difference between a hybrid (the Seek, I guess a performance hybrid), and a Trek “fitness bike” and a cyclocross? Also, which is best for climbing? I assume the cyclocross. I have some near murderous hills in my area. I also like that the Seek has disc (Avid Juicy) brakes. And, by no means a disparagement to cross riders, I just don’t like curved bars anymore. If the added speed on the cross is because I can hit a down position, I don’t find that too great a value. Also, going over rough terrain seems harder with the curved bars, isn’t it?
Bikes seem to be advancing like computers. 10 years ago, it wasn’t this difficult. I was agreeing with Cisco that hybrids brought out the worst of all worlds. Now, it sounds like hybrids do everything well, just not great. I would love to have a huge quiver of bikes, but I’m looking for the “one bike” right now. Thanks for the links and the input!
Oh, lastly, what are the view of shocks? I used to have Rock Shox Judy, but I found them no different than any other Rock Shox. Do they justify their weight? The reason I ask is that in order to help me make my decision, I want to prioritize in order of importance what a bike should have, stock, in order to do what I want (go fast on road, and take it on light trails).
Here’s what I think:
- frame material
- fork
- seat post
- tires
- derailer
- shifter
- brakes
- shocks
- ???
Cross bikes will go faster because they are lighter, have less rolling resistance, and are more efficient at putting power down, not because they have curved bars.
I guess I am confused about what you’re really looking for as far as terrain capability. You say you want to be fast on the road, but then you bring up front shocks and disc brakes. What do you mean by “light trails”? Just dirt? Cross bike will be superb, and not slow on the road with different tires. Rocks? A suspended mountain bike will handle it well, but you will be slow as crap on the road, as you know since that was your original problem.
Just as a note, your road biking friends will be tooling around on 700x23 tires, riding bikes that come in at 15-20 lbs, clipped in. You are talking about looking into bikes that will be riding on wide tires, and in the 25-30 lb. range. Do you think you will keep up with them, and have fun doing it? Just for comparison sake, this weekend, I hit 47mph on a not-particularly steep downhill on my road bike. Any idea how fast you are normally going?
IMHO, get a cross bike, and an extra set of road wheels/tires. If your wedded to the idea of a flat bar, commuter type, may I recommend the Jamis Coda? Steel frame, triple crank and 700x28 tires. You still won’t keep up with your friends, but it is a solid, all-around bike.
ETA The Coda Elite is even lighter, with disc brakes, clipless pedals and a carbon fork.
Hybrid bikes are really aimed at people who aren’t that bothered about the whole cycling experience. They’re good for commuting but I wouldn’t choose to ride one even for that. You’ve been out of the game for a while, mazinger_z, but it sounds like you want to ride your bike at a level above the casual cyclist - go fast, explore trails etc. Don’t waste your time with a hybrid.
To be honest, you may be happiest reversing your priorities and just getting a hardtail mountain bike (no rear suspension) - you’ll have a great time and there’s surely people you could ride off-road with. You can ride fast on the road - sure if your friends are intent on chain-ganging it round the place you won’t keep up, but is that the case?
I think we need to know how fast you want to go on the road. If your friends are up over 20mph, and depending on how strong a cyclist you are, you might have trouble keeping up with them on anything less than a true road bike. If they are more in the 18mph range, then the cyclocross would work. If they are slower than that, then one of the hybrid dealys might be OK. It will mostly come down to the engine, though. I’ve passed some roadies while on an old mountain bike and have been passed by other roadies while on my tri bike.
A cyclocross bike is a racing bike, but it is designed for the mixed surface and often muddy courses that these races use. They are light because most races re hilly and have obstacles that require the rider to carry the bike over. The gearing is easier than a road bike, so you should be able to climb very easily, but you’ll lose speed on the downhill since you’ll run out of gears.
I was hoping after 10 years, the market would develop an all-around, all-purpose bike. It seems close, but development in other areas (like road bikes) make the need for different bikes a necessity.
If I ride in the city, the people I ride with are on high entry level/mid-level bikes, think Specialized Allez triple. But, they aren’t that fast. On my mountain bike, Schwinn Moab 1, my best average was 17 mph on this one off-road course (mostly flat and hard, some technical aspects). The last race that put me into retirement was more like 9 mph. I’m probably averaging closer to 15, lifetime. My friends on the road bikes are clocking in around 18-20, sustained, flat road.
Where I live, the city is flat and fast. In the suburbs, it’s hilly, but usually short, though really steep. The trails around my house are usually hard, crushed limestone or paved, but, especially if off-road, can turn hilly and rocky quickly, sometimes muddy (I live by a bunch of streams).
I don’t mind getting blown out on the downhill, I just want to keep up on the flats. Oh, and easier climbs would be nice, though I just look at that as part of the workout.
Oh, and this just got me thinking: what is comparable to a Moab 1 nowadays?
Mountain biking has fragmented a huge amount in the last ten years, in the minds of marketing men. You’d laugh to see the pigeonholes the sport is pushed into by the manufacturers - sort of the opposite of the all-purpose bike direction you refer to. Agressive XC trail bike anyone?
What has really changed in MTBing since you were riding is that suspension is now sorted out and fairly well understood. 10 years ago you were still seeing some comedy frame designs to accomodate the rear shock. These have all gone now, the designs are solid and shock technology has improved a fair bit too. What this means is that you can walk into any bike shop and a mid range Trek / Giant / Spesh full sus will be a really nice bike. Schwinn, alas, has gone - swallowed up by a giant conglomerate that doesn’t give a shit about cycling. A sad end to a great piece of American cycling heritage.
The other major change is that disk brakes are now standard on a MTB, more or less. Lower end bikes will have cable disks, which are actually fine, whereas higher end bikes have hydraulic disks.
People have also realised that full suspension is not automatically the answer to the riding you may want to do, and hardtails remain as popular as ever. Back in the late 90s I remember people predicting their demise.