Originally Posted by
psystemupdate
i forgot to emphasize that 27.5" wheels cant keep up with 700c tires and this is alpha gold aluminum from trek, so it should be lighter....the extra weight from the schwinn mountain bike is coming from the extra rubber on the tires and the fact that its cheap walmart aluminum.
to suggest i use 26" tires seems contradictory to the problem im having and would make it worse....we ride long, not in town, meaning any time we go over 7 miles then round trip it, we are going to not be doing equal excercise.
To answer your original question, there's no reason you can't throw gravel tires on the Trek, with respect to tire clearance. Trek aluminum will certainly be lighter but only by a little.
Why do you believe 27.5" wheels can't keep up with 700c, regardless of terrain? Your companion is going to have to work harder because the ratio of her weight to the bike's weight is greater. Certainly, you can alleviate some of this by buying a lighter bike. But smaller diameter wheels do not increase or decrease rolling resistance compared to a larger diameter wheel (unless you're riding at 25mph or more).