I’m curious if there’s good research on what differences in effects of weight that people can reliably sense while riding a bike.
I start here with a lot of baseline skepticism, because humans can be really effective at placebo-ing themselves, or attributing differences they actually feel to an easily-measurable thing (e.g., bike weight).
Of course the bike industry has a long history of the tyrrany-of-the-easily-measurable, from Tour mag’s BB stiffness test to “this frame is 7% lighter” (you’re almost certainly not going to notice the 50g in a blind-test riding environment).
I found myself thinking through this again when finally finishing Alex’s review of the new Scott Addict RC (posted nearly 2 months ago). I enjoyed the review and the bike sounds lovely to ride.
But I came away skeptical on this point, where he compares to his 7.3 kg Tarmac SL8:
getting the bike back up to speed takes less effort and happens far quicker, thanks to its lower weight
Taking Alex’s 7.3 kg reported weight for his Tarmac SL8, and doing the math on using the same tires (+130g per wheel as reported in the article), and splitting the difference on whether his SL8 was weighed with or without pedals (so: adding half the weight of top-level pedals to the Addict), let’s say we’re comparing 7.3 kg for the SL8 vs 6.3 kg for the Addict. That’s a 16% weight difference between the bikes, but of course the bike is still a small proportion of the total mass accelerating out of a corner while riding.
If Alex weighs 60 kg kitted out, that means we’re comparing a rider+bike weight of 67.3 kg to 66.3 kg - a difference of 1.5%. Is the feel of accelerating on the Addict RC the result of this ratio (1.02, or 0.98, depending on what’s the denominator), or more likely some other combination of factors? I don’t know Alex’s sensitivity accuracy, but I’d generally put my money on “Alex is mostly noticing factors other than the weight difference.” My skepticism here, if warranted, only makes the Addict sound even impressive; the difference in ride feel while accelerating sounds lovely, and is consistent with the rest of what Alex wrote about the ride quality in this review.
But it brings me back to whether my skepticism is warranted. Generally: it totally is. But that doesn’t mean it is with Alex. There’s a lot of variation in people’s ability to notice differences. Some pros (Mark Cavendish and Cadel Evans come to mind) are reportedly able to notice small differences in fit, without knowing that any differences existed (i.e., mechanic mistake. I’d expect the same is true for ability to notice weight differences. Of course reviewing the-lightest-off-the-shelf-road-bike is not a blind test, but it doesn’t mean that Alex isn’t noticing the 1.5% lower rider+bike weight when he accelerates out of a corner.
There’s also the question of whether “feels faster” equates to “is faster.” Not directly relevant here, and not something Alex made claims about, just a similar issue.
