Hey everyone. I'm 51 and have lost 145 lbs in the last year. I'm getting pretty fit and just started riding a bike again after 25 years of being too fat to sit on one. I bought an old Trek 820 Single-track with steel frame. I'm 6'1 and 180lbs with a 32" inseam and this Trek is 17" from the crank tube to seat stem tube top. I put a 5" riser so my handle bars are even with my seat. Point being I will soon buy a bike that fits me.

Now to the main question. I've put over 100 miles on this bike so far, just enough to maybe start knowing how I like to ride. Most of my rides are on dirt roads and I find myself exhilarated by speed. At first I could barely run on the low side of the gearing on my rides and just use the 1-7 on only the low side. Now I find myself always in the high side and mostly in 7 wishing for more pedal.

I won't be doing any significant jumping and I won't be trying to get hurt at 51. I ride some rough hillsides but the bigger bumps cause my hands to hurt bad for days if I really get into the rough stuff, thus my style is mostly smoother track but fast as I can go, which isn't likely fast by most standards but I've only been riding again for about 2 months.

I live within 2 miles of old dirt roads and logging roads where I could do 30 miles or more without repeating a trail. There are no bike parks designed for riding close to me but plenty of forest gravel roads and trails. Point being I'll never ride a lift to the top of a mountain just to ride down fast.

I think I want an XC bike as light as I can afford, but I want something comfortable enough that I enjoy riding it every day, so a lighter hard tail trail bike is also a thought.

Any of you older guys ride an XC bike? Do you ride light trails with it also?

I ride an enduro type bike, 160mm fork with 150 in the back. I like rough trails with bumps, rocks, and sand. I'm 65 and 210#.

If I was riding fire roads and mild trail I might look at trail bikes with 120-130mm suspension. People go fast on hardtails but suspension saves me from lack of skills, bad eyesight, and poor line choices.

I'm on a XC 29r Full Suspension... 100mm front and back.
Handles pavement, dirt roads, gravel roads, fire roads, mild single track with the small knobby tires I put on.
Kenda Small Block 8 and now Vittoria Mezcal tires.
I'm not into Downhill or rock bound single track...(although I like going downhill)
With your size I'd look for large/xlarge frame/19 in. 29r. w/good airfork in front at least.
29r rolls over stuff and rides better on pavement.
I never put the bike in car... just ride to trailheads.
Good on you for starting with old bike to know what your riding style/needs are.
Oh... and I'm a senior citizen.

Thanks guys. A 29er is what I want. Do you guys think I would be better off with a 1X11, 12? or more traditional 3X8 since I stay mostly in the high side of my 3X7?

Fairly sure I want a hard tail. I don't think I need the weight, complication and cost of a FS bike. I might try one though and change my mind. I've rode a couple different Trek bikes to try but didn't know enough to know what I wanted so I bought this old bike to learn.

Right now I think I want a Giant Talon or Fathom. Not sure which one. I would basically like the lightest with best shifting components. I don't like the rough stuff but I do ride some bumpy rutted out grassy hillsides. I don't think suspension will be as much of an issue as weight and shifting.

Pretty sure there are no triple cranks on those bikes. I have a 1x11 and it has the low gear I need and never runs out of high gear unless I'm on a flat road.
I think all the modern stuff shifts well. A double crank can give you more range than a single.

A rear suspension will make the rear brake work better and allow the rear wheel to maintain traction better than a hardtail, but a hardtail can certainly be flogged by a skilled rider.

I would take measurements of your bike and compare them to the geometry charts of the ones you are looking at, unless you have the chance to actually ride them. I'm kinda hard to fit and I am pretty happy with the way my bike fits, but sizing is all over the place on mountain bikes.

My MTB is a full rigid. The 2.3 tires on it are plenty of cushion for the rides you mentioned and that keeps it simple.

Congratulations on dropping all that weight. If that isn't deserving of a bike present to one's self, I am not sure what is.

Just to introduce a different idea: Have you considered a so-called gravel bike? Basically a road bike that is very capable on trails. This would give you the lightness and speed you crave. Some versions come with modest suspension too, if you feel you need it.

I just saw this last night: https://opencycle.com/wide

There are many, many other options now. Some are even quite affordable.

Get a fat bike they are simple light weight fun and easy to ride. No drama no suspension sans the big tires. they are a blast and can be had for a relatively low price. At 53 I enjoy the MTB bike every now and again but I have 5 bikes of every category
Go for it. I also use a Suspension seat post a Good One Thudbuster and it takes the edge off. Keep us informed.

I picked up a 2017 Marlin 5 but was distracted when I bought it and it has a warped rear wheel. It's all I wanted in a bike though, light,locking suspension ,disc brakes and 29" wheels. I paid $200 and it looks show room .Even has the rubber whiskers still on the tires but The rear wheel is warped. I drove two and a half hours to get it and got really bad news right before I got there,so I somehow missed the warped wheel.

It fits me perfect though and still rides and climbs 10 times better than my old bike. I've been told a new rim is about $100 so I will still have a fair deal on a bike I wanted.

Nice! That looks like a lot of bike. Have fun. Maybe the wheel is salvageable?

It is obviously warped when I spin it but there are no real lose spokes and I can't hardly notice any ride difference until I'm in the 3 highest gears wide open. I think I'll ride it a bit, maybe try to learn how to straighten it with a spoke wrench. Unfortunately it's a bit over an hour just to get a wrench.

I just may learn more about tinkering with these bikes on this one since it fits me. I may just play rough on this rim and buy a new set of rims and tires later. I saw some that looked pretty fair for a set on Amazon for around $150. I would rather wait and learn enough to do it myself than pay the bike shop as much for onerim

XC full suspension get one ride it and enjoy, thank me later.

Any particular brands, model I should try?

Depends on your local bike shop that you like and what brands they carry. My favorite shop carries trek, giant, Santa Cruz.
I currently ride a giant stance 1. Got it on a closeout for a steal. Getting ready to buy a Santa Cruz tallboy. Depending on budget I can recommend both of those bikes. You an get the giant stance pretty inexpensively or step up to a trance. The Santa Cruz tallboy and 5010 are great choices. You don’t need an expensive bike to have fun. I will never out ride any bike at this age(57) so for me getting a quality bike is an investment to last a long time. I gave the same advice to my 76 year old friend who was getting his first mtb bike and after a couple of rides he’s in love with the sport. Trail riding is a blast, doing high speed downhill is fun but I have a family to feed and need to be at work on Monday so XC is a perfect choice for me. Good luck and have fun, let us know what you end up with to share in the glory

I've ridden a hardtail MTB since early '90's (I'm 68) and still ride similar to what you describe. I still will ride over rocks, roots, take drops that aren't way high, and still do it on my '96 GT hardtail (with all upgraded parts). Sounds like a lightweight hardtail would be fine (wish mine was a little lighter)

If what you ride isn't too gnarly you might want to consider a cyclo-cross bike. Just for visual example, this is my Colnago World Cup CX.

I have bad wrists from years of wrenching wrong. They are arthritic along with my elbows. Off road riding is hell on those joints so I bought a Giant Anthem. It is a very compliant bike, handles well, and is superb on gravel, however, it is overkill for the smooth stuff.

I now have a vintage F500 Cannondale with Headshock and a Thudbuster seatpost. Not as supple up front as the Anthem, but it is not a tunable fork, either. I find it just fine for gravel, but too harsh for off road stuff since it does not have the travel in the fork or the air spring that I really need. Go with a front suspension hard tail and add a Thudbuster.

I'm looking at x/c and trail hardtails. For me, I just don't see the need for full suspension. I am looking at bikes with a 120mm or better travel air fork, 1x12 drivetrain, and tubeless ready wheels.

But you have some gnarly, rocky trails in Tucson. Full suspension makes them fun. I know, people go fast on hardtails but I love the dual squish.

What you described riding sounds more like gravel bike terrain than MTB. Definitely not full suspension MTB. I know people who enjoy riding dirt/gravel roads on rigid or hardtail MTBs (I'm not one of them), but I never met anyone who would choose to ride them on a full suspension bike unless that was the only bike available to them.
I love riding MTBs on singletrack and I love riding full suspension MTBs on trails with rock, roots and jumps, but give me my drop bar rigid gravel bike with 700cx42 tires for dirt roads and gravel.

Just do some rentals or demos! Full suspension is nice. Hard tails are versatile. I traded a full suspension Diamondback Release in to get a Salsa Timberjack with rack options for commuting and a quick release for a trailer hitch. The full suspension wasn’t useful enough, but I really liked riding it. They’re both trail bikes. I think XC bikes are a bit too focused.