Troll MTB like 26" wheel, 520 is a 700c wheel .

I have bikes with those wheeltypes, but not those , MY LBS sells Trek, and can get QBP stuff

Surly and Salsa are the QBP brands..

no problems with either of your choices..

a 3rd option, since you are tall, is a 29er trekking bike , 700c wheels,

but capable of taking wider tires than will fit the 520.





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