2

I'm using a road bike more than 2 years for holiday tours and commuting.

  • Merida Scultura 903
  • Shimano Tiagra groupset (50-34, 12-28)
  • 8-9 kg
  • 700x23 tyres

Now i have plans to switch to touring bike. Expected:

  • VSF TX-Randonneur
  • Shimano 105 groupset (50-39-30, 11-43)
  • 14-15 kg (with tubus etc)
  • 700-43 tyres

I am really wondering about performance / speed change? Does anyone experienced this kind of process? Typically my speed is 30/32 km/h in flat roads.

  • 11-43 sounds like a really wide range, especially combined with a triple. Do you mean 11-34? – Kibbee May 16 '16 at 12:43
  • 2
    I'm pretty sure he means 11-34 as that's what is spec'd with the bike on the manufacturer's page. – Benzo May 16 '16 at 12:46
  • It looks like there is a typo on at least some versions of the english & german language pages that says 43. Others say 34. In all likelihood, it is 34. – renesis May 16 '16 at 14:57
  • If you're saying that you will be touring with exactly the same panniers, etc, as before, under the same conditions, the difference in bikes will have a negligible effect on your speed. The wider tires will slow you down very slightly, and of course a heavier bike will be slower uphill. If, on the other hand, you're switching from regular riding to loaded touring, the additional panniers will contribute both wind resistance and weight. – Daniel R Hicks May 17 '16 at 1:17
3

There are a lot of factors that go into your speed and efficiency, and this switch touches several of them:

  • Rider Position: Typically, a bike with touring geometry will have a slightly longer wheelbase, and lower bottom bracket. Along with other geometry tweeks, the result is that on a touring bike you are likely to be in a slightly more upright position, increasing your wind resistance.

  • Weight: As in your example, touring bikes can be 2x heavier or more. This doesn't make as much difference when you are already up to speed and on a flat road. Weight makes a huge difference in acceleration and climbing.

  • Rotating Mass: Some portion of that additional weight is located in your wider and heavier tires. This increases the rotating mass of your wheels and will also have a negative impact on your acceleration.

  • Racks, Bags, etc: Having panniers, handlebar bags, and other equipment attached to the bike, in addition to increasing the weight, will act like small parachutes and slow you down.

With all of those factors it's difficult to give you any kind of narrow estimate. I can tell you my experience, switching between riding a carbon-fiber racing bike with a small backpack, and a steel touring bike with one or two panniers attached. I find that over a 13 mile urban commute (relatively flat, but with a large number of potential stops) I am 15-25% slower on the touring bike. For me, much of that is a result of starts and stops (the acceleration effect mentioned above.)

  • Rotating mass directly affects acceleration, not speed. Heavy wheels are thus slower to get up to speed causing the bike to feel less "zippy", but you can still reach the same top speeds. A heavier wheel has more momentum so will keep more speed when travelling over bumps, possibly making you faster ( a reason mountain bikers prefer 29" wheels for example ). – Nic May 16 '16 at 20:34
  • Actually they are preferred because they have a higher angle of attack and roll over things better. They are actually less preferred for more technical riding because the weight makes them harder to get back up to speed. If the heavier weight was actually an advantage, they wouldn't be selling nearly so many carbon 29'r wheelsets. – Deleted User May 17 '16 at 0:11
  • "Rotating mass" is highly overstated as a problem. If the mass is rotating it has the effect on acceleration of twice as much mass fixed directly to the bike. Given that the rotating pieces are, relatively speaking, quite light (even with "heavy" tires, etc), the difference is likely to be unnoticeable. – Daniel R Hicks May 17 '16 at 1:08
0

In terms of weight, it makes no difference either way ( according to this scientific paper - http://www.bmj.com/content/341/bmj.c6801 However there are other resistances to motion that differ between your bikes, namely rolling resistance and air resistance, that will affect performance

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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