Originally Posted by
tjspiel
The problem I have with the numbers you're using is that while 25c is a common size for a road tire, 1" is NOT a common size for a MTB tire. By choosing a tire that small you're eliminating the softer ride, the go anywhere capability and the flat resistance that many here claim as MTB advantages.
The rim on a typical road bike obviously has a larger diameter but they are usually thinner than MTB rims. Typical MTB tires I would guess are MUCH heavier than a typical road bike tire and I might just throw my tubes on a scale because I bet the MTB tubes are heavier too.
I think you can make the argument that you could get an MTB wheel/tire combo that has less inertia than a typical road bike wheel/tire combo but then again you can also get some very light road rims and tires or for that matter there are road bikes that use 650C rims.
In other words by choosing certain tire/rim combos you can stack the deck one way or another. Unless you're using typical sizes I'm not sure what value the argument has.
no deck-stacking intended... tho in my case i'm sure everyone can tell I sure prefer the mtb
for rim weights, take a look at Mavic or any other rim co's site. Their CXp rims are 470g+. Open Pro is 435. For mtb, their xc717 disc is 395g. xm 317 is 440. Assuming 26" rims are heavier than 700c rims is not valid - good general-purpose rim weights are pretty close mtb vs. road. And, this is a kicker, the 700c rims is bigger, so more inertia....
Of course, heavy duty mtb rims meant for freeride or whatever are heavy. So are 700c rims meant for touring or whatnot.
standard Performance road tube is 117g. mtb tube is 176g. I'll give ya that - tho I bet a lot of mtb riders on skinnier slicks are using the smaller 26" tube, 129g. I sure was - couldn't stuff that fat tube in a skinny tire. fwiw, i converted my tires to tubeless early this year.
On to tires - the $8 Forte City ST is 455g. The Slick City is 350, Fast City is 400, Michelin TransWorld are 700, my Conti Sport Contact are 370g, and my new Marathon Supremes are 595. so.... kinda hard to say what the "typical" is, as all are popular!
For road bike commuter tires - i doubt many road bike commuters are using 200g uber-tires. I'll bet most are in the 26-32c range - and 300+ grams. The popular Gatorskins are 300g.
so please plug your numbers in there & see what ya get. the math is straightforward & eye-opening. Really makes you want to take weight out of your wheels.
On my personal bikes, the mtb has less inertia, more rolling resistance. On the road bike, I accelerate slower, but to a higher cruising speed. since my commute involves no more than about 1/2 mile of continuous cruising, and many stops/starts, i ride the mtb.... among other reasons.
results may vary, and past performance does not guarantee future results
