Slave Posted June 17, 2009 Share Happened a lot when I did a lot of road running. You enter a race and they rate the course at 15 km. You run a stonking time and get all gagga because you "aced" it. Then you find out the course is short or not the full distance. This happend during Foutains yesterday. The course route is rated as 96 km. I guesstimate that someone measured it a long time ago. From Line to line, I measured it on my bike speedo as 92.93 km. Ox's Gamin said 94 and a bit. Am I the only one that finds this irritating? Link to comment Share on other sites More sharing options...
The expat cyclist Posted June 17, 2009 Share One word: STANDARDS! Everyone uses a different device to measure distance and unless we all (good luck with that) use the same device, there will always be short courses! (Or long one's...) So when they say the race is 30km - they mean it is in the region of 30km! MJ loves MTB2009-06-17 02:11:38 Link to comment Share on other sites More sharing options...
Spinnekop Posted June 17, 2009 Share Yup.......you're the only one..... Link to comment Share on other sites More sharing options...
AfreekduSoet Posted June 17, 2009 Share Def the only one. What makes you think your device is correct? Why has Ox's Garmin got a different reading? Seems your device is not reliable. Also, there are a couple of settings on Garmin which could also affect the accuracy. Link to comment Share on other sites More sharing options...
Dirt*girl™ Posted June 17, 2009 Share ..give or take a couple of km's....who cares, just enjoy the race. Link to comment Share on other sites More sharing options...
Shebeen Posted June 17, 2009 Share Am I the only one that finds this irritating? enjoy the Knysna MTB long course. They call it a 85km marathon every year, but it's only about 74km. Even looks all impressive on your pedalpower seeding with the av speed you get! Link to comment Share on other sites More sharing options...
Slave Posted June 17, 2009 Share Yeah, I agree, not all devices measure accurately. I set up mine on the measured rolling circumference of my loaded front wheel. I expect that it would be close. Cateye claim 98% accuracy. Not sure how the Garmin was set up, but that takes readings from Satelites so I expect it will be the closest thing to the real deal. Trubie sent me his polar readout for the ride. His distance shows 91.8km. So, assuming we take an average of all of them, it is still way less that 96 km which the race was rated as. Therefore my time time of 2 hrs 49 is actually pathetic because it was a short course. Link to comment Share on other sites More sharing options...
Tumbleweed Posted June 17, 2009 Share ask nancy what happens when a polar reads the race as longer than it is. Link to comment Share on other sites More sharing options...
Tieffels Posted June 17, 2009 Share Dude that is like 3.2% error, not bad at all. I've done MTB races that are out well over 10% distance wise. I also remembered talking to they guy who did the argus on a trike, he took all the outside corners to stay out the way of faster riders, ended up doing more than 120km's. Link to comment Share on other sites More sharing options...
AfreekduSoet Posted June 17, 2009 Share Would expect the Garmin to be closest but it could still be inaccurate depending on setup (gps filtering, record frequency, fix quality etc). Why is Trubie's reading lower than yours??? You lot should have a meeting and discuss why you yourselfs cannot measure accurately before getting die donder in with race orgs. Link to comment Share on other sites More sharing options...
Slave Posted June 17, 2009 Share OK, so maybe I'm reading too much into this. The Garmin (just recieved the specifics regards the ride) shows it at 93.01. That's close enough to my 92.93 so I'll accept that my Cateye is accurate enough for me. 91.8 on the polar (Trubie) is also close enough. The course was 4 km short. I'm not bothered that is was short. I just expected it to be closer to 96 than it was and it takes away from the time I did. Target time was three hours. So I thought 2 hr 49 was great. (Not so great any more.) Link to comment Share on other sites More sharing options...
Canaris Posted June 17, 2009 Share with road running there is an allowance of about 1% of total distance. Also the route must be measure with a wheel thingy to ensure that it is correct.With cycling however, the distance is very much a guess-timate. the new popular way is to measure it out on a map and then transfer the track to google earth or some GPS software and let the comupter do the maths. This way however does not take the ups and downs of the terrrain into consideration. Also with MTB with windy bits of single track are also a real challenge.So from experience you have to be forgiving for up to 5-10km of the distance out. Link to comment Share on other sites More sharing options...
Minion Posted June 17, 2009 Share This way however does not take the ups and downs of the terrrain into consideration.The ups and downs are insignificant. If you were to do 100km (measured horizontally) at 10% gradient , the true distance would be 499m longer i.e. an error of less than 0.5%. Link to comment Share on other sites More sharing options...
Trubie Posted June 17, 2009 Share OK' date=' so maybe I'm reading too much into this. The Garmin (just recieved the specifics regards the ride) shows it at 93.01. That's close enough to my 92.93 so I'll accept that my Cateye is accurate enough for me. 91.8 on the polar (Trubie) is also close enough. The course was 4 km short. I'm not bothered that is was short. I just expected it to be closer to 96 than it was and it takes away from the time I did. Target time was three hours. So I thought 2 hr 49 was great. (Not so great any more.) [/quote'] Slave - this is not really an issue, last year's 94.7 was about 92k's long. If you find a race that is exactly right, you are very fortunate.Point is its just us slow coaches that worry about the time too much. The guys/gals that race, just worry about the positions they get. We just worry about it to make sure seeding is improved, etc.Dont brake your back about it. I use 2 devices for exactly this reason. The Polar and the Topeak I use always differ on the distance. Both have been set exactly according to the specs, by a LBS. I realized 1:45 into the ride yesterday that I hadn't started the Polar, hence the reason for the 91. My Topeak (which is set on auto start) registered 93.75, which is very close to what you and Ox measured. If you look at that graph you will also see the time is about 2 min slower (2:47:44 or something). My topeak time was 2:49:19, and I see you have a time on Racetec of 2:49:11. Pretty close I would say, so dont worry, just be happy.With the warm up I registered 104.98 k's for the day. Link to comment Share on other sites More sharing options...
NotSoBigBen Posted June 17, 2009 Share Trubie - BTW my Polar CS200 showed 93.7. So since mine and your topeak showed such close readings I guess ours are the one's to follow in the future Link to comment Share on other sites More sharing options...
gremlin Posted June 18, 2009 Share I wonder if they going to get the Beker Bundu Bash right this year, Advertised as 30km and we only did 21.4km, 7.6km short. Link to comment Share on other sites More sharing options...
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