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Cycling for Noobs

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fetcheveryone Jun 2023 4:58pm, 22 Jun 2023 29,210 posts	Quote Pin fetcheveryone I've been faffing about with Fetch Mile data, and come up with an interesting graph. I looked at the top 100 mile times at each gradient from -10% (i.e. big downhill), through to 3% (somewhat uphill). You can grab this data for yourself from fetcheveryone.com/mile-fastest.php Although it's always possible that any given mile time is skewed because of what came before it, the data here represents the best outcomes for the top 100 cyclists. A few more caveats: 1) Fetch miles aren't, strictly speaking, miles. They are comprised of 10 data points along the route, each with an 80m hit radius. So it is possible to hit all the data points in less than a mile. 2) I trimmed out the top 10 times, because the data got a bit wiggly. I'm calling those 'special cases' - the freakishly good athletes, or the freakish performances at least. With the remaining data, I amended each data point so that it was relative to the zero gradient. For example, let's look at the 11th fastest cyclist. On the big -10% downhill, they got a Fetch mile time of 1m37s. On a flat mile, the same-placed cyclist managed 2m28s. So I express the -10% data point as 153% i.e. they travelled at 153% of the pace of the flat ground cyclist. When the downhill was less vicious e.g. -5%, they travelled at 144% of the flat ground cyclist. Going uphill at +3%, they travelled at 52% of the flat ground cyclist. I repeated this for all the cyclists at all the gradients. Then I calculated the mean relative pace at each gradient. I looked at the variance of the data, and although there was some, I haven't reported it here as I don't think it detracted from the outcome. Here then, is the graph. Gradient is along the bottom, with downhill on the left, and uphill on the right. Zero gradient is our sea-level, so it makes sense that cyclists here are travelling at a relative speed of 100%. At a 1% gradient this falls to 76%, at 2% it's 58%, and at 3% it's 46%. On the flipside, a 1% downhill produces a speed of 113%, at 2% it's 118%, and this figure gently rises until we reach hills of 7% gradient and above. Here, it seems that increasing gradient offers no further improvement. In my case that's because I'm holding the brakes and screaming. I've no doubt there are some more extensive analyses, with bigger data sets, and with more formalised data, and by mathematicians who know what they're talking about. This was just an hour of fun with a bit of coding, and some faffing with spreadsheets. But it feels like a reasonable tale, so I thought I'd share.
MudMeanderer Jun 2023 8:37am, 23 Jun 2023 2,419 posts	Quote Pin MudMeanderer Good stuff, Fetch. It makes sense what you're seeing there. If we look at the equations of motion for a rider at different gradients, then we can see at lower speeds we have a linear relationship between power (to weight) and speed dominating. This explains the right hand half space. At higher speed (left hand half space) the cubic drag terms dominate, so it takes a bigger incremental power for every unit increase in speed. So even if you're not holding the brakes, and you have a sustained straight steep descent, you most likely won't see a massive increase in speed as the gradient increases downward. This sort of stuff can be used for tactics in racing and particularly time trialling on rolling courses - when will slight variations in produced power give the biggest net improvement.
DrMags Jun 2023 8:44am, 23 Jun 2023 64 posts	Quote Pin DrMags Fascinating, Fetch 🖖🏻 Nice to see the data showing that you can’t go fast enough downhill (screaming or not) to “make up” for the uphill slog … i.e. a flat course is always faster than a hilly one of the same length. I wonder if the curve would be similar for running, or even more pronounced towards diminishing speed advantage on the downhills 🧐🤓 As an aside re: comparing sports, I’ve compared cross-country skiing (me) with snow-running in winter spikes (NordRunner and based on one example (!), although it’s faster skiing the downhills than running them, having “planks of wood on the feet” is quite a disadvantage on the uphills. It took us the same time to complete the same ~15km undulating route. Caveat: this is comparing a competent runner with a semi-competent xc skier (I wasn’t born with them on my feet)!
Groundhog Jun 2023 4:09pm, 29 Jun 2023 5,651 posts	Quote Pin Groundhog My 10 year old second hand road bike is getting a professional service for the first time in its life. I thought I'd treat myself It will include all new cables, cassette and wheel bearings and should feel like a new bike. Care of Dave's Cycle Works in Wokingham.
Groundhog Jun 2023 4:09pm, 29 Jun 2023 5,652 posts	Quote Pin Groundhog And new chain, obvs.
lammo Jun 2023 4:13pm, 29 Jun 2023 12,078 posts	Quote Pin lammo Whereabouts is that Groundhog?
AndyS Jun 2023 4:42pm, 29 Jun 2023 2,140 posts	Quote Pin AndyS 1) Fetch miles aren't, strictly speaking, miles. They are comprised of 10 data points along the route, each with an 80m hit radius. So it is possible to hit all the data points in less than a mile. Turn's out it's also possible to take a bit over a mile 🤣 (Even I'm not that slow - this was closer to 100 miles...)
GordonG Jul 2023 11:27am, 10 Jul 2023 9,853 posts	Quote Pin GordonG Before I start a new thread just wondering if anyone on here can help, please. I've used the Cycle to Work scheme to get a new bike via work a couple of times and it always seemed reasonable. But applying for another today, I'm wondering if i've misunderstood it. the bike I'm looking to buy is about £930. My expectation is that, because I don't pay tax on what effectively is a company load, after a year I'll own the bike and will have paid less than £930. But on the Cycle scheme website today, it's quoted me that I'll be paying back 12 payments of £86.99, totalling £1043. What's my incentive here? Is it that I pay £1043 over a year, but that figure isn't taking into account the savings in tax? Otherwise, I'm not sure what the point of the scheme is. ta
MudMeanderer Jul 2023 11:52am, 10 Jul 2023 2,424 posts	Quote Pin MudMeanderer I've never used it myself, but my understanding is that the price you pay is taken before tax, so you're implicitly paying less. Maybe a better way to think of it is that you're paying the same absolute amount, but it's a smaller fraction of your take home. The saving you make will somewhat depend on where you are relative to tax bands - if they're taking an admin charge and you're at or below the income tax threshold, it may not actually work out better.
57.5 Degrees of Pain Jul 2023 1:48pm, 10 Jul 2023 13,272 posts	Quote Pin 57.5 Degrees of Pain I did the scheme in the autumn. £1043 is taken off your pre tax earnings so you effectively pay 25% or so less if you are a basic rate payer, 42% for a higher rate payer.* * Not 100% sure what English rates are.