I’ve been experimenting with mountain biking in the last year, after decades as a road cyclist. Since I wasn’t sure I’d take to it or what kind of rides I’d end up doing, I limited my initial investment to a used Gary Fisher Big Sur (26” hardtail) from 1997. I felt immediately at home on that bike with its stretched out, road-like position. And it works pretty well for the riding I’ve gravitated toward: mostly smooth singletrack and gravel roads with long climbs.

Now I’m considering buying a new bike to take advantage of some newer tech: 29” wheels, 1x drivetrain, better suspension fork. But I’m hung up on how different the geometry of new bikes is. I’ve mainly been looking at XC models, but a new XC bike seems more similar to a new trail bike than to this old Big Sur. I got that impression from looking at the geometry charts, and riding a range of models at my LBS. They all seemed squished and upright compared to what I’m used to.

So my question is, what are the benefits of this geometry and riding position, and should I try to stay close to what I have or let that go and embrace modern MTB design? The LBS salesman said comfort was a benefit, but I haven’t felt uncomfortable on the Big Sur. Internet searches tell me that XC bikes have become more like trail bikes because XC racing courses have become more technical. I'm not seeking out technical routes, but here are three specific situations I’m curious about:

• I’ve been on tight switchbacks and quick curves that I could barely get around on this bike, and all newer bikes have a longer wheelbase. Will this be even more of a challenge on a newer bike?
• It takes a lot of concentration on steep climbs to keep the rear wheel from sliding while also keeping the front wheel from lifting off the ground. Would a newer bike be more stable in this way?
• If I’m climbing and encounter a root that’s more than a few inches high, it’s very difficult to get over without stopping (most of my falls have come from trying!). Could a newer hardtail help with this, or is this more a job for a full suspension (and/or more riding experience)?

At this point I haven’t seriously considered a full suspension. While that might open up more trail options for me, coming from a road background, a full suspension system just seems intimidating. I think I’d rather stick with trails that have minimal roots and rocks, plus gravel roads and an occasional paved section connecting them.

Sticking with the Big Sur is also an option, but I’d at least like to upgrade the fork and I haven’t found any new models that have the correct travel and brake mounts.

1997 Big Sur specs:
71 head angle
74 seat angle
161mm steerer
? stack
640mm reach (25.2”)
290mm BB height (11.4”)
38mm offset
74mm trail
1030mm wheelbase (40.6”)
560mm handlebar width

New XC bikes I've looked at have a wheelbase of around 1100mm, a reach of around 410mm and a head tube angle of around 69 degrees.