rob e wrote:wombatk you've got me there..........anyone with a garmin want to give that route a try?.....i am confident on 15% though.
i know its a tough one because one of our mates who was 11th out of 520 in the Dirtworks 50 admitted to thinking he might have to unclip in 39x25. We have done a lot of climbs together including Otford Wall with confirmed 12%+ first pitch and this is easily comparable for steepness, but certainly not length. Dundas street is the kicker...
Okay, it's gravely steep. So steep that my Edge 705 gave me frequent ridiculous values for gradients (like negative gradients on Dundas St, followed by > 30% gradients).
This was most likely due to the random errors in elevation data often exceeding the difference in elevation over short distances (e.g. 0.5 m error in elevation is quite significant when points are just 10 m apart). On steep roads like this, the accuracy of a GPS is questionable - as the hill itself can obscure some satellites. And finally, the Garmin appears to average or smooth gradient data over either some distance or time (I haven't worked out which) in ways that don't seem too clever.
So with these caveats on accuracy, I tried to work out what gradients could be calculated from the raw elevation data and coordinates logged by the Garmin. This gave something less ridiculous.
From the start of Oberon St to the peak of the climb on Rainbow St, the road rises approximately 48 m over 300 m - an average gradient of 16% (this is the average of three laps on that section). The gradient is above 15% for over 240m, and when you first enter Rainbow St from Dundas St, the gradient is over 20% for 40 m (maybe as high as 25% at its worst).
The gradients on Arden St are somewhat tamer. For example, the worst is the hill from Dolphin St on the southern end of Coogee beach - it reaches 15% for the last 30 m or so before Alison Rd.
Here is a graph showing the elevation (on right axis) and gradient (on left axis). There are slope lines that represent a 1 in 6 (16%) gradient also shown as a guide to the steepness...
The bikely path is here: http://www.bikely.com/maps/bike-path/Ra ... -Challenge .
For anyone looking for a punishing workout, this ought to satisfy - there's even a nice little warm-up climb up Beach Rd, and plenty of other hills in the area with serious gradients. The Oberon/Dundas/Rainbow St loop is not for the feint-hearted, which counts me out. I'd happily give anyone who can do this in 39x25 a standing ovation.
In terms of steepest gradient, Rainbow St probably beats Bowen Mt. However, Bowen Mt has gradients around 12% that are sustained for much longer distances. The vertical distance climbed is an aspect of "steepest" that needs to be considered, and I suspect that Bowen Mt would take more grunt to execute that Rainbow St.