treebound 

CliffordK

There may well be benefits of shaking it up a bit. So, a heavy bike one day, and a light bike another day. I find that towing or hauling cargo, I tend to get quite a bit different workout than riding a light road bike.

The important thing is to ride whatever gets you out riding and that you enjoy. My observation is that people riding nice bikes tend to ride further, longer than those riding poor quality cheap bikes.

KraneXL

Not one bit. As long as you generate the same amount of energy you could be riding your big wheel. However, if the ride isn't enjoyable, you're not likely to keep at it or ride for very long.

rubiksoval

Comfortable and fast is fun. I wouldn't ride a mtn bike because it's slower. I'd rather go fast. Always.

wolfchild

I ride fixed gear on the road and single speed MTB on off road trails. Top speed and how many watts I put out is not my priority, I just ride for fitness and enjoyment.

Carbonfiberboy 

I ride tandem with my wife for most of my outdoor riding specifically because it is harder per mile than on my single. I do the same rides on the tandem that I'd do on my single. My answer to the OP is that a heavier bike will get you more fit as long as you ride the same yearly miles you'd ride on the lighter bike. If it's by hours, then it probably makes no difference unless you'd ride more hours on a faster bike, in which case it's the other way 'round.

FrenchFit 

Beyond the obvious, your riding style changes pretty dramatically depending on your bike.
, at least mine does. Especially on hills....

Mix it up.

CliffordK

My HEAVY cargo runs really beat me up.
My long rides also beat me up... but differently.

I suppose riding just beats me up.

I suppose I have always been a slow rider, but somehow on a short ride on my road bike of say 10 to 40 miles, I just don't get the same energy expenditure as the heavy cargo runs. Although I suppose I come close if I try to average 20 MPH for a moderate length ride.

BloomBikeShop

The great thing about cycling is that you can get fit and have a heck of a lot of fun at the same time!

So the specifics of the bike don't really matter, as long as it's one you want to ride.

Seattle Forrest

Road bikes are geared for riding on roads. Hybrids are geared for going slowly on MUPs. Depending on your fitness level, it may be a challenge to sustain the same effort on both.

treebound 

jeffreythree

I view this as the faster the bike, the farther I can go in a set time. If I want a good workout while staying in the neighborhood, I ride my cheap 40# fat bike. It is like weight training compared to my road bike, especially if I throw in some mini hill repeats. Change it up even more by putting that mtb back on the trails instead of being a glorified hybrid. I just did that to my old Trek 920 and made it single speed as well.

ColonelSanders

An important factor is whether one type of bike inspires you to get out and ride more than another type.

AlmostTrick

Mix it up, ride what is fun for you. Power meters not required.

canklecat

I had to switch from my road bike to my hybrid this summer after a shoulder injury and aggravated old neck injury (I was hit by a car in May while I was riding my hybrid to join friends for a casual group ride). I tried sticking with the road bike for awhile, starting about six weeks after the injury with the road bike on an indoor trainer and one or two road rides a week of 20-30 miles. But it was aggravating the shoulder and I was miserable at night, couldn't sleep.

A friend who kept my hybrid over the summer helped me make some modifications. I switched from the riser bars (low rise, very slight back sweep) to Nitto albatross. I tried 'em flipped but it was still too much pressure on the bad shoulder. Now I've been riding that hybrid with the albatross bars for about a month: bar in conventional position, grips roughly at saddle height, reach significantly reduced compared with drop bars or even the riser bars.

Much more comfortable. And the albatross bar offers a surprisingly versatile range of hand positions, so I can get a little more aero for head winds, or lean forward and make more efficient use of the thigh adductor muscles for climbs. It's really nice in traffic.

My hybrid is close to 30 lbs, and I'm riding fairly wide but reasonably lightweight tires -- Conti SpeedRides, versatile for pavement or light gravel/groomed chat trails, even grass and some muddy conditions. Great tires. Not like slick 700x23 road bike tires by any means.

Anyway, I can't tell that I've lost much in fitness, aerobic conditioning or legs when I do switch to the road bike. There are differences in positioning, sure. And the road bike has clipless pedals, while I still prefer platforms for the hybrids. So I have to consciously adapt my pedaling style for the first few minutes of each ride. Biggest adjustment is having to remind myself to unclip on the road bike, and to *not* unclip on the hybrid. I actually nearly fell a month ago at a stop sign when I tried to unclip my sneakers from the hybrid's platform pedals, and panicked when I didn't feel the reassuring click of Look pedals and cleats unclipping. I kept twisting and twisting my heel as I slowed down and finally jerked my left foot free from the non-existing retention, lost my balance, and just barely caught myself from flopping on the street. Right in front of a puzzled driver behind me. A bit embarrassing.

And the shoulder feels much better than past couple of weeks after reducing pressure by sticking with the hybrid and more upright bars.

I still use the road bike on the indoor trainer about once a week, mostly for interval training sessions of 30 minutes. It's still uncomfortable on the shoulder for longer rides or sessions. But it helps reinforce that clipping/unclipping thing too. I'm actually more worried about self-induced unclipping falls on my bad shoulder than anything else.

And I'm still riding the same 20-30 mile routes at the same speeds overall on the road bike. I'd expected to lose a lot of fitness over the summer (I'm also recovering from a thyroid problem and facing surgery soon). But I've managed to hang onto maybe 75%-85% of my peak fitness from before the injury.

I suppose I shouldn't be surprised. The hybrid is less aero, heavier, has less efficient pedals, heavier tires, etc. Strava guesstimates my energy output is actually higher on the hybrid at 12-14 mph than on the road bike at 15-17 mph.

Even switching between saddles hasn't caused any problems. The hybrid has a soft progressive density foam saddle with Lycra fabric over the foam. It's quite wide for my narrow butt. I sit upright and just wear ordinary clothes, no padded shorts. My road bike has a fairly firm, 131mm Selle saddle and I use various brands of padded shorts and bibs. No problems switching between the two saddles and clothing types.

So switching bikes didn't put my conditioning back nearly as much as I'd expected. I'm looking forward to getting back into peak shape by next spring after the surgery and full recovery.

zacster

Hmmm. One thing I didn't see mentioned here is how efficiently you get to that watt of pedal power. The basic estimate is about 25% efficiency from watts expended to application to the bike. A road bike uses the pedal stroke in the most efficient manner, whereas an old upright clunker does not. A MTB is somewhere between, as is a commuter, so I'd expect somewhat less efficiency with those too. So not only are you paying a penalty for the heavier bike in terms of speed, you are paying a penalty in conversion of calories burned to pedal watts.

One way to test this is to ride both a road bike and an MTB with both a power meter and an HR monitor. HR will be indicative of work produced by the body vs. the pure power on the bike. You can keep power steady and see where your heart rate goes, forgetting about speed or distance. This of course requires all other thing being equal, which it never is.

RogueJay

Have to admit I chuckled at the end! And for what it's worth, I don't own a power meter (too expensive) and my racing cohorts raz me about it. I do see the training benefits for them but I see too many of them get burned out from chasing watts.

joelcool

This is obviously a personal choice. What matters to me may, or may not matter to you, or anyone else.
For me, I much prefer to ride my CF road bike, clipped in. I do not race, and only compare results with me. My carbon bike responds so much better to my efforts compared to the MB, tandem or winter commuter that it sort of inspires me to give the sort of effort required to get the heart rate up and put more watts down.
In theory, of course, one could pedal any bicycle for the same duration and get the same fitness results, but for me, I'll choose the roadie.

wphamilton

Not really but I've been told (and it makes sense) that if you're putting that many hours on the bike it does matter that the bike is comfortable and performs well. By which I mean, it shifts when you want it to, the brakes stop it well, it handles the way you want it to without rattling your teeth, you have no concern about something suddenly breaking.

It seems to me to be analogous to your office chair. Since you spend more time in it than anywhere else, it logically should be the most expensive highest quality thing that you own. But like the bike it's not, in my case, but it makes sense that it should matter.

Riveting

If I only cared about fitness, I'd only ride my full-suspension 29er with 2.3" tires (or a fat-bike). Either is super comfortable and can handle any terrain you're willing to throw at them. But Strava MAKES me care about distance and segment speed, so I log most miles on the CF, which has a power meter.

mcours2006

If you don't care about fitness you could just ride a heavy clunker with knobby tires. Heck, you could even just run!

I enjoy riding my lighter bike over my heavy bike any day. I care about fitness, but it's much more fun to go faster, and if I have more fun then I'll ride longer. Riding longer means better fitness. So, in the end, a lighter bike will make you fitter.

Myosmith

While nobody likes riding a clunker, any well functioning bike appropriately suited for the purpose (no monster knobbies on the MUP) will provide a good cardiovascular workout with some strength benefits, if you put in the effort. I don't have any high-end, ultra-lite bikes but the ones I have are well made with mid-level components. They both fit great and they are very comfortable and enjoyable to ride. IMHO, that is the key, having a bike(s) that are comfortable and that you enjoy riding so that you ride regularly. BTW, on 100+ mile rides my average speed drops by less than 1 mph on my flat-bar mutt with 32mm tires, than it is on my cro-mo road bike with 25mm tires of the same brand (Bontrager AW3 Hardcase Lite). Of course on shorter rides with lots of hills and sprints, the lighter road bike is quicker but I don't think I get any better workout.

You do have to consider just what you mean by "fitness" as there are many parameters that can come into play. Are you looking for endurance, peak output, strength, some kind of combination? I wouldn't pick an ultra-light TT bike if my goal was to do 10-hour endurance rides, even though it might be "faster".

u235

Bingo. A while ago I put about 2k in a year on tank 35# hybrid. I was getting a little bored. I added a gravel bike and soon after a XC hardtail. Dropped like 10 minutes from my routine exercise route the first time out on the gravel bike. I immediately switched to a 20 mile to a 30 mile routine. On my XC I was going places much more challenging and much further. It's not like I suddenly became a better, faster rider overnight, the bikes opened up more opportunities for me. I wanted what others stated, to go more places and for longer rides and I wasn't getting much improvement on the hybrid and losing interest. As time goes on I am still going further, faster, and riding longer. This follows the law of diminishing returns though. It gets harder to get a big difference without paying big bucks... Unrelated, I don't know about a "Big Wheel" but I'd rock a Green Machine any day.

riccofiori

It is always better to ride a bike that shifts well, corners well, descends well, brakes well, feels good on longer rides, and is dependable (all of the above). This gives the rider the ability. To concentrate on having fun.

bruce19

Start with the question.....How do I want to ride?