I’m mostly a roadie but have been getting into MTB more and more. Been doing local races and riding the fast group rides, so speed does matter.. Mostly riding steep, loose, rocky single track climbs and descents in the Northern AZ pines... Fairly technical and challenging climbs, intermediate/black diamond type trails but nothing too gnarly...

I have been riding a small 15.5in 26” 2010 Trek Top Fuel 9.8 which I have enjoyed and am comfortable on. I’m 5’2” 100lbs.

It was a pretty high end bike for its time, around $4k. Full suspension 100mm RP23 shocks and Fox fork, Deore XT 9 speed triple, XT disk brakes, carbon post, Race Lite wheelset, Rocket Ron’s, etc...

I need to know realistically how much faster I would be on a brand new 2018 FS bike of similar spec (~$4K). I know bigger wheels are better, and frame geometry has changed. But how much of a difference can these things possibly make? Would Nino Schurter get smoked if he was forced to compete on a 9 year old machine on similar terrain?

If I were to get dropped on a 2010 Top end Carbon road bike, I wouldn’t be able to use the bike as an excuse. My buddies would just laugh. On the road, it’s all about the legs and lungs at that point.

But my MTB buddies keep telling me I have to get bigger wheels if I wanna keep up..

I’m trying to decide if getting maintenance on suspension, upgrading the wheels, tires, getting a fitting done would make more sense than trying to sell the bike at a steep loss then spending a ton on a new bike + fitting. I’ve got the cash for a new bike, but I sort of have a hard time believing that a new bike would be that much faster...

IMO, A $4K bike from 2010 is not slowing you down in any meaningful way.

And at your size you might not end up on a 29er, anyway, even of you did buy a new bike.

i guess it really comes down to how much difference very small improvement will make for you. The higher level you are racing at and the closer to the podium you are, the more these little things matter.

I would check out 29” and 27.5” bikes at your height. Pro rider Emily Batty is around your height, and she switched from 29 to 27.5.

I don’t trhink the question here is whether she is better off with a 29er (or 27.5) or a 26er for XC. (I don’t think anyone is going to suggest that the 26er is preferable)

Her question is whether it is worth spending 4K just change her wheel size.

Yes , a 29er does roll over things better, and that is particularly helpful with shorter travel XC bikes. This is what she will be getting for that $4K if she goes with a 29er. And that is it.

The part about going farther with each pedal stroke is just a gearing issue, and seeing as you can be in whatever gear combo you want, it is not a point for or against the larger (or smaller) wheel size.

And, if it does turn out that you prefer 27.5 to 29, the argument to spend $4K just to go from 26 to 27.5 is even harder to make.

Hey, I realized I assumed you were a woman, without any clear indication of that.

Anyway, regardless of which restroom you use, it is really hard to say how much the difference is going to mean to you.

in terms of time on the clock, it wil proably make a small difference, but not enough to determine if you can “keep up”. My guess is that if you are at the back of the pack now, you will still be back of the pack, unless you have been right on the tail of the guy 2nd to last. Then you will be 2nd to last.

It has been a few years since I cared enough to read them, but there have been studies attempting to quantfy the difference between 26” and 29” in terms of lap times around various courses. As I remember, there usually was an advantage to 29ers. But the difference was pretty small, and nothing to go buy a new bike over.

To me, the advantage is more in how they handle rocky terrain. More of a subjective thing than time on a clock.

It is also important to consider WHERE it is you feeling slower than the rest of the A group. Climbs? Rolling flowy stuff? Technical pedally sections? Downhills?

And to reiterate my point yet again: at your hieght, you may prefer a 27.5 over a 29er. And in that case, it gets really hard to make the case for dropping $4k JUST to go from 26 to 27.5. That is really not going to make a lick of difference where you place in the pack.