I guess it depends on how bumpy you mean - just normal chewed-up asphalt or cobble stone....
I've only ridden one bike recently with front suspention, and I quickly dismissed it for paved path riding because the bounce caused a noticeable loss of pedaling effeciency.
I tested a ton of bikes this past weekend, and the Surly Cross Check stood out among them all for how it handled bumpy pavement while still seeming fast. I can't remember exactly what size or kind of tire was on the Cross Check. Depending on how your rides are, you could always consider a lock-out front shock. But if we're talking "best of both worlds," my opinion would have to be for the bigger tire.
Mongoose passed on to my son, Miyata, Tailwind, V-Rex, De Rosa, Safari, just added a Bike Friday
I just went for fat tires on my recent bike purchase. An REI Novara Safari. Bonus - I can ride the occasional gravel or dirt sections I run across from time to time. And will be using it on some unpaved canal paths in the near future. For what it's worth, I've used a suspension seat post in the past. Didn't seem to suck any energy out of my pedaling and did take the road buzz off my keister. Big bumps, I've always handled by unweighting the bike for both hands/arms and seat.
I think it depends on how rough the pavement is. I would prefer thin tires and suspension if the pavement was smooth but cracked so that the tires rolled well but had to contend with an occasional large bump, but I would choose larger, softer tires if the surface was continuously rough so as to make a bike vibrate even if you weren't striking a large irregularity such as a crack or a pothole.
I think that if you go with fat tires, the construction is very important to rolling resistance. It's not just rotating mass. It takes energy to deform the sidewall and the tread, and not all of that energy is returned because of internal friction in the rubber. That's why car tires are speed rated-high speed can make them heat up so much that they fail. That energy comes out of rolling resistance. You want a thinner tread and a fine, high TPI sidewall without a lot of rubber on it, but if the tire's too thin, it can be a liability where the road is rough because sidewall abrasion can cut and ruin your tire.
I am sure you are also aware that you'll have to avoid or slow down for the sharper bumps which are higher than your tire's sidewall because they can cause snakebite flats. I think you'd have to go quite large on the fat tires to make them handle the situation as well as narrow road tires at high PSI.
Last edited by garage sale GT; 07-26-10 at 08:29 PM.
I have an old Trek tourer that's lived about six lives--it was my main ride for four or five years, then got cyclocross tires and lower gears, then upright bars and a tall stem as a town bike, and I've ridden it a lot on fire roads and doubletrack in the desert. It's a singlespeed now, with mustache bars and 41mm tires. It's also had a suspension post off and on, and for awhile I used a suspension stem with elastomer bumpers, called a Flexstem, I think (that was a long time ago). Never tried a supension fork on that bike, though I have on others.
As several other posts have said, different setups do different things. The Flexstem didn't do much at all, maybe a little relief from the buzzies on chip seal. The post (a cheap one, not anything good like a Thudbuster) helped a little on moderate bumps, but I learned my skills on mountain bikes a long time ago, before suspension was even a rumor, and I reflexively stand up for bumps anyway.
Biggest all-around difference, and certainly the best bang for the buck, was larger tires at lower pressures. There's plenty of room on that bike, and I like at least 35mm, maybe fatter, at 80 psi or below (NOTE: I weigh 240, so YMMV). On my Atlantis, my main bike these days, I run 37mm Paselas at 75 or so, and it's nice. I've used the same bike with 25s at 105, and it was much less comfortable without being significantly faster.
Probably I'd make a different choice for racing or full-on dirt, but for all-around riding, that works for me.
You can ride off road for the rest of your cycling life with the right tires. I have a old road bike I pit 35mm knobbies on and i ride it all over logging roads, trails etc. To me suspension is great but certainly not needed for off road riding.