I’m doing this same exercise and keep going back and forth. Here are the points I’m considering in addition to the pros/cons listed by others:
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I’m pretty sure all my high gear riding would be on paved roads that get me to and between trails. I think either option would be fine for this but the 29" might have a slight advantage.
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For really steep trail climbs the 26" seems to have an advantage but lately I surprise myself on climbs every time I go out on the 29".
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I like having the 26" as a bash-about muni for playing around and would be disinclined to treat it this way with an expensive hub in the wheel.
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Unlike Ben, I don’t feel an ungeared 26" with 150mm cranks is too slow on trails. But I do agree with him about the 29" rolling obstacles more easily.
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My 36" with 137mm cranks is great on fire roads and smoother trails. According to Eric’s chart a geared up 26" wheel with 150s would give about the same gain ratio. Despite that, I’ve read enough Schlumpf threads to know better than to expect that the 26" in high gear will ride as easily the 36". Still, I’d like to think that some day I’d have the skill to ride these areas in high gear on the 26" but it would be tougher on the 29".