2

I'm new to cycling and got a cheap (not the very cheapest probably one step up) mountain bike as a way to get around the country lanes in Cornwall, with the odd rough track here and there down to a beach.

I am curious about the quantitative differences I'd see if I had:

  • The same type of bike but much lighter

  • the same bike but more road focused tyres

  • an actual road bike

My interest is more on ease of getting up hills and conserving energy in general than raw speed... Can anyone give me firm figures or real life comparisons?

Improve this question
8
  • You can put some 5 kilos on a backpack and see how that amount of weight affects your biking. I tell you beforehand this is going to be very noticeably uphill.
    – gaurwraith
    Sep 4, 2016 at 17:52
  • 1
    Does your MTB have suspension? That adds a lot of weight and makes cycling less efficient because you're spending energy flexing all those springs and shocks.
    – David Richerby
    Sep 5, 2016 at 9:18
  • Front only, the cheap full suspension MTB was several kilos heavier!
    – Mr. Boy
    Sep 5, 2016 at 12:29
  • 3
    So that purring sound of my knobbly tyres on the smooth road is the sound of inefficiency?
    – Mr. Boy
    Sep 5, 2016 at 12:43
  • 1
    @gaurwraith: put that weight in a pannier and you'll have a much tougher time noticing.
    – whatsisname
    Sep 5, 2016 at 23:16

2 Answers 2

Reset to default
8

Bicycles, like many machines, are efficient, but a large amount of energy converted by them is not in fact used for their "intended" purpose: The largest energy sink is air/wind resistance, which you can only very marginally improve on a "normal" bike†. However, wind resistance squares in relation to your speed, so maintaining a more leisurely pace would improve your efficiency. For example, people riding on cross-continental tours actually ride pretty slowly compared to e.g. people riding a road bike for training: They do this so that they can put in longer distances over the whole day rather than pushing themselves as hard as possible for e.g. 5 hours and then being destroyed for at least a day.

The second biggest contributor to the bicycle's lost efficiency is rolling resistance, as you seem to already realize; Therefore, getting a bicycle with proper road tires will drastically improve your riding speed and efficiency over riding a bike with heavy-tread mountain bike tires. As a real-life example, I can easily handle 50+ km in a few hours on a 40-year-old ten-speed without really "pushing" myself past my limit but on a mountain bike this would probably kill me.

Lastly, weight is very important when riding over hilly terrain but less important on the flats. However, you stated that you are riding over hilly terrain, so reducing overall bicycle weight might actually make a big difference for you even if it doesn't improve actual mechanical efficiency much: Humans are extremely complicated machines and we only have a very narrow power band, quickly becoming exhausted once we leave this particular "sweet spot" of cadence and load: If your cadence is too high you run out of breath but if your load is too high your body starts using anaerobic power and builds up lactic acid in your muscles, which wears them out.

TL; DR

If you have the money, go look for a decent used road bike (even if it's old, it's likely going to be more efficient than a fancy new mountain bike)-- if not, go look for decent road tires for your current bike. However, no matter what you do, ride your bike at a casual pace because you'll go further without getting worn out.

† You can significantly reduce wind resistance by riding a bike with full fairings but, for your stated purposes, this would be a bit ridiculous.

Improve this answer
11
  • Do slicker tyres make much difference on steeper hills where you're traveling slowly, or is that simply a question of muscle and weight?
    – Mr. Boy
    Sep 4, 2016 at 13:15
  • I don't know through personal experience, but I would venture to guess that, yes, the lower rolling resistance would make going up hills easier, but the improvement probably wouldn't be as "noticeable" as on the flats because you'd be putting in extra effort anyway to overcome the grade whereby the only thing holding you back on the flats is wind and rolling resistance.
    – errantlinguist
    Sep 4, 2016 at 13:27
  • A problem with old road bikes is that they usually come with a 42 teeth "small" ring, and not much more than 23 in the back. You may be better off on a mountain bike uphill because the easier gearing, but take a modern road bike with a compact cranckset and you will fly compared to both a mtb and an old road bike
    – gaurwraith
    Sep 4, 2016 at 17:55
  • Regarding air resistance I reckon the only time I go fast enough is when I don't particularly want/need to go faster still ;)
    – Mr. Boy
    Sep 4, 2016 at 21:01
  • You are using the term efficiency rather loosely, and bicycles, along with many other machines, are remarkably efficient, often approaching 99% and better in terms of energy put to the pedals being put to the road.
    – whatsisname
    Sep 5, 2016 at 23:12
1

Riding around makes your legs stronger and unless you're speeding around it's pretty effortless most of the time after a while.

Mountain bikes are much better on the road with slicks or road tyres. I have a big heavy 29'er which takes more effort to pedal around than my lighter touring bike, but after 8 months of riding, it's not a huge difference and I use it every time I'm going anywhere which isn't strictly on the road.

So for multi terrain and comfort disregarding speed, I prefer the mountain bike. Note mine is a big one with 29 inch wheels, it may well be different with the smaller 26 inch ones. The touring bike does hills a little better because it's lighter.

I tried a road bike and didn't like it, uncomfortable to ride, scary skinny tyres and just don't seem to be made for cruising.

I actually think it's better to start with a big heavy bike, you build up strength and fitness faster, and those are the 'real' measure of how easily you conserve energy and get up hills. Bikes have plenty of gears to help you out, and I found hill climbing is partly technique rather than brute strength. A lot of the secret to conserving energy is technique (possibly more than the bike).

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.