Singlespeed & Fixed Gear - FG/SS Commuter/Trail bike

OK, here goes.

I have a '94 Alpinstar MTB that just hangs on my garage wall. I also have an '87 Schwinn Tempo that I converted to FG at the end of last year to see how I'd like it. Most of my riding is commuting to work which is split between my FG bike and a TT bike I have for triathlons. I also have a soon-to-be 7 yr old son who is prime and ready to tackle some trails on his BMX bike.

Now, the way I see it, I have a few options:
1) Redlilne Monocog 29'er with some non-flat bar and a flip-flop wheel. I found a frame/fork from Nashbar for about $180. I could set it up as a do-everything bike and get rid of both the MTB and FG. I don't think I'd find a setup I'd like due to the long top tube.

2) Surly cross-check. I can get a deal on a used frame/fork. I'd probably buy a new set of wheels and goto ebay for what I can. The only downside to this I can think would be the shifter mounts.

3) San Jose/Paddy Wagon/One Way/whatever else?? Again, get rid of both the MTB and Schwinn and have a brand new bike (I haven't had a new bike since '94).

4) Keep Schwinn and MTB and get a new wheelset for the Schwinn. It really is a nice bike and it fits me well. If I had a complaint about it, the standover is pretty high (34"), but the top tube is perfect at 58cm. I could then either keep the MTB geared or do a simple single speed with spacers/derailleur.

Probably if I go with either 1-3, I'll be more motivated to get to the trails which I consider a good thing.

Anybody have any other options or experience to what works best for a mostly FG commuter with an occasional, 7yr old level trail ride?

The Monocog 29er stock bike is a bit of a tank, but I don't know how much of that is the frame. Unless you're going to really be abusing it off road I'd go for the Cross Check. It has rack and fender braze-ons which are useful for commuting duty as well. As for the shifter mounts, you might want to mount shifters on them someday.

Raleigh also has a nice looking steel rigid ss 29er that might fit the bill.

why not buy a surly hub and rebuild the rear wheel on the bike you already have

I would really love to see an Alpinestars SSed. I used to have such bike envy for those rigs.

I put rebuilding my wheel with a flip flop hub under option #4. The biggest problem with it is that I'd like the extra space with one less bike. Also, regardless of how quickly it will wear off, that new bike smell is quite a bit exciting.

The Alpinestars was my dream bike in college. I got a decent 8 month internship before my last semester in college and made some decent money and treated myself to this bike at the end of it. I rode it quite a bit during that last semester, but when I graduated, moved, and got a real job, it mainly just sat.

Hmmm, maybe I should think a little more about that option.

I have a friend who tried to do the same thing as you, find a bike he would use for both road and MTB as a fixed/SS flip-flop. Got a Rivendell Quickbeam. Loved it but realized it was not a substitute for a real MTB. After a year of trying this option he just bought a Monocog. He couldn't be happier.

Really, there is no substitute for a true MTB off-road. I have a Cross-check that is primary my fixed gear road bike but I throw knobbies on it to go off-road. Lots of fun, keeps you skills sharp and it handles well for what it is but when I head out on it I know it's going to be a much different experience than my MTBs.

My vote: Keep your fixed roadie and either build up the Alpine Stars or grab the Monocog frame for cheap.

My bike does pretty much what you're talking about I think. It's an IRO Jamie Roy built up in a sort of cyclocrossish style. Click pic to biggify.

http://eternityfuture.net/__oneclick_uploads/2006/11/pict5825-01.thumbnail.jpg (http://eternityfuture.net/__oneclick_uploads/2006/11/pict5825-01.jpg)

if you really only wanted one bike, with a 29er you could get two chainrings and/or a flip flop, two lengths of chains, and two tire sets, etc. that way you can set up your bike before you leave the house... fixed commuter with a taller gear ratio and smaller tires, or a small gear ratio with a freewheel with big tires for the trail.

i have a splined sun-ringlé ss hub on my 29er. that way i can run 32:18 for the trails, or install a smaller cog and perhaps even 'cross tires for riding around town. i've yet to swap tires for city riding, but sometimes i'll pedal 32:16 around town on my 2.3"s.

i sometimes ride my 'cross bike on single track and love it, but it really is no replacement for a mtb.

My bike does pretty much what you're talking about I think. It's an IRO Jamie Roy built up in a sort of cyclocrossish style. Click pic to biggify.

http://eternityfuture.net/__oneclick_uploads/2006/11/pict5825-01.thumbnail.jpg (http://eternityfuture.net/__oneclick_uploads/2006/11/pict5825-01.jpg)

I'm diggin' the style of your build. Nice!