Garmin Bike Speed Metric – when does it make sense to use speed?
I suspect that many cyclists with power meters have wry smiles on their faces when they hear other cyclists talking about speed. “So, what’s your average speed on this ride then? How fast can you normally go?”
We all ‘know’ that speed is irrelevant as it is oh so easily impacted by slope and wind. But is it really always irrelevant and are there any valid times to use it?
You’re pootling along behind someone at 250w and then when it’s your turn, you crank up the watts to 350w. After a minute or so or so you look behind to find that you’ve left everyone behind and promptly have to slow down.
A good use for speed is that it gives you a better indication than power about what effort level you need to maintain when it’s your pull. 30mph when following someone broadly translates to 30mph when it’s your turn to work.
Plus, as @Eric points out below, average speeds of local routes or average flat speeds are often used when organising group of rides for riders of varying abilities. Broad speed levels are a good way to indicate likely effort to a wider range of people who might have very different power abilities, weights and riding positions – it would seem churlish to talk to a casual group about their w/kg or normal cDa.
Doing A Time
I had a few cracks at my 10-mile TT PB/PR last year. I was doing it on a somewhat awkward route where grades varied quite a bit in places.
On my first attempt, I paced my efforts to average just under my current 20-minute power from an indoor test. I also tried and succeeded in keeping my NP within 5% of the average. From memory, I failed by about 15 seconds. Maybe the wind should have been better factored into my power calculation.
A couple of weeks later on the same course, I targeted an average speed. With a couple of miles to go and the harder bits polished off, my average was below where it needed to be. At the end of the 10 miles, I think I was about 45s faster than my previous effort and so 30secs under my old PR. #Result ! I’m still not quite sure how I managed that, the conditions were very slightly better but not 45 seconds worth of better. Maybe it was because I paced myself using speed but running the risk of blowing up.
Does anyone care what anyone else’s average Strava segment power readings are? Other than to check for someone cheating, I don’t.
Strava segments are all about time and, as the distances are fixed, this means it’s all about speed. As we all know, if the wind is blowing the KOMs are falling, which is partly why Strava is nonsense, albeit addictively interesting nonsense.
You Don’t Have A Power Meter
Hey, why not use speed? You need something to fill up the screen of your Garmin/Wahoo 😉
You Want To Obey Speed Limits
At least in the UK, cyclists almost always do NOT legally have to obey speed limits, the limits only apply to motor vehicles. If you are being nice then you might want to give fellow cyclists a good name and stick to them in any case as no one else realises that you are riding legally.
Richmond Park (one of the UK’s Royal Parks) used to be thought to be an exception as there was widely believed to be a valid bye-law that placed an additional requirement on cyclists to adhere to the motorised speed limit. However, the Park Authority rather cleverly wrote to someone (image above) and confirmed the speed limit does not apply to cyclists. Indeed the only speed laws that do apply to cyclists in the UK are based on ancient legislation around “wanton and furious cycling” which is probably equivalent to reckless/negligent/dangerous cycling (which doesn’t exist as a law). So there we have it, if you keep your cool and don’t get angry you can go as fast as you like anywhere.
Hey…be sensible. Check the speed as shown on your Garmin/Wahoo.
Garmin Cycling Speed Metrics
Garmin has a nice range of cycling speed metrics. They include various averages for the ride, the lap and your instant speed. There are also some nice charts and dial (see image at the top).
Buy a power meter if you can afford one. Power is just better and almost always more useful.
A 4iiii or Stages G3 single-sided Shimano 105 crank PM is more than good enough for most people.
Perhaps think about adding back a speed data field to one of your secondary screens and/or your TT/PR profile
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