Big(ger) Frames and Thin Skinned MTB Tires

I am confused. Occasionally on this forum, and since I’ve been riding bicycles since from the early 90’s to now, I’ve seen 2 themes I don’t quite understand. Looking for some discussion here.

  1. 2 frame sizes fit (the key is they both fit, meaning 50/50). Always pick the bigger one. Because you might grow into it? Because one is making up for other inadequacies? Because it weighs more? This one makes no sense, except when you get a second water bottle perhaps.

  2. Thin skinned tires for MTB races. I mean thin sidewalls/casings, and not puncture resistant construction. I find that when I race, I have less selection of the line, and am more likely to put my wheels in less than optimal locations than when on trail/training rides. I know I go faster on descents while racing as well, so I put my tires in harsher conditions in races. This one feels like, “IF YOU AIN’T FIRST, YER LAST!” Reese Bobby, 2006. Unless one actually is contemplating the win vs. Flat and lose, you might want tires designed to survive the day, and maybe the next day, and probably the day before. Shouldn’t tire selection be more about the tread pattern for the conditons (moisture/sand/mud, roots, rocks, etc.), and less about how skimpy the casing is? Is it because its smart to ourchase disposable, one rsce tires? I can’t think of the benefit of wanting to plug, or boot and tube in a race (and then throw out afterwards). I know I couldn’t do that faster than using a set of tires thst weighs 200g more.


  1. personal preference, in theory, the larger frame is more stable and the smaller bike is more agile (like the modern long slack geo). Because of the geo changes, maybe you can’t put a shorter stem on a large already long bike, and you maybe you don’t need an already long bike in a larger size. so it depends :slight_smile:

  2. If you need marginal gains to podium, you might take the risk of more supple / thin tires, but you have to find out for yourself how big the change is on a punctured or slashed tire, some people ride so light that they can get away with any tire, anytime, anyplace, others flat by just looking at the tire… And goals are not equal for everybody too, it’s personal if you would rather DNF then finish 2nd with 1 second difference.

in short, no right or wrong, just personal preference and consideration

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  1. I think this comes from the shift in sizing being measured top tube to bottom bracket to reach being the critical factor.
    And the trend now is longer=better.
    Hence go for biggest possible size.

  2. Thinner casing / higher TPI = better(not more) deformation and therefore grip. There’s way more to this then tread pattern.
    Also lighter, more supple tires are more fun. I don’t race but gravitate more and more to the lightest possible I think I can get away with because of bike feel. That is on our local trails, if I go to Sierra Nevada or the alps for a week I go with burliest possible I think I can pedal up on the big days. YMMV

  1. Easier to run a shorter stem to make the bike fit than a longer one and still retain good handling. All things being equal. But rarely, if ever, are all things going to be equal.

  2. I rarely, rarely, ever see that anywhere.