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On a Strava segment featuring a 80-100m-long, 40-50m radius curve going downhill on a paved road at about 8-10%, I make generous use of my brakes out of fear of wiping out on my 23mm, fairly slick road tires. Because of this, my 30-second time is almost double that of the KOM, which seems borderline unsafe from my point of view.

I suppose this is actually two questions:

  • Is it likely that the KOM has some special downhill setup on his road bike?

  • If not, what are some best practices to quickly go down a downhill curve on a road bike without losing traction/having a wipeout/otherwise having a bad day?

  • 2
    For the first, probably not. Descending takes a lot of practice to get over the fear of going down quickly, and how to control the bike at speed while resisting the urge to slow down a lot. Professional riders can descend safer at higher speeds than normal riders can, so you need to know/find out your limits. It – Batman Nov 1 '15 at 20:42
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    Winds make a huge difference - There's one long downhill near my city (Gebbes Pass, Christchurch, NZ, aka "the bastard" 4.2 km and 8%) and one day I had to pedal downhill to get up to ~40 km/h because of the headwind. Naturally the wind had petered out by the time I wanted to come back up ! – Criggie Nov 1 '15 at 21:32
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    @Criggie also perhaps several descents in a session to know the surface on the day, and following another rider whose actions would tell the KOM whether to expect anything oncoming. – Chris H Nov 1 '15 at 21:44
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    @Criggie just be aware that there are recumbent riders and at least one velomobile in Christchurch. 55kph is quite reasonable on the flat on an upright, and in a decent velo with some crazy person in it it's easy enough... and the velo is owned by Steve Gurney. For that matter I've been clocked at 70kph through the middle of Stoke(Nelson) on an upright and that's flat. Oddly the cop who followed me then ticketed me was also doing 70kph and "keeping up with the flow of traffic" in a 50kph zone. Ticket stood {swearing} – Móż Nov 1 '15 at 21:57
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    @Criggie - the road's actually usually empty. It leads down from a car road to a pedestrian/cycling path almost immediately after it levels out, and it's just occasionally used for deliveries to facilities at the bottom of the hill. The segment is here, and the grade does seem to be 7% on average, my bad (I've always got trouble gauging these things). KOM apparently did it at a ridiculous 89.0km/h in 11s. – Jules Nov 1 '15 at 22:03
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Focusing on the strava bit - its a screwed up strava track. The track shows they flew, and strava's point-grabbing routines have gone wonky. Short answer they did not do it in 11 seconds.

They are bike rides though - just a fortuitous error on the GPS signal makes it look like they were faster, and much more direct. I suspect there's some obstructions in the way (like a big `merkin freeway bridge thing) that are capable of interrupting and limiting GPS positional signals. So when they get around the corner and get a better fix, it looks like they've gone really fast. Its happened to me elsewhere.

There are no easy fixes.

  • You can flag the whole ride, which is somewhat draconian.

  • You can go out and ride faster again (you've tried, its really hard)

  • They can crop that piece off the end of their rides (but its in the middle for both top riders)

  • They can use something like SNAP (strava needs a polish) at http://strava-tools.raceshape.com/snap/ to generate a "polished" file to re-upload and delete the original. (image below)

  • You can tell strava to only show your own results in the preferences, and stop caring so much about KOMs. Remember you're only competing with yourself, despite what strava imply, so its your own results you want to beat. I've got some KOMs, and they're not that special. Seeing my own improvement over time, that's special.

Here's a pic of SNAP showing the sugested tweaks for the KOM holder's ride enter image description here

4

Gummier tires (that won't last as long) have superior traction. As far as I am aware, that is the only advantage the KOM may have over you.

On dry pavement, slicks have more grip than tires with treads, so your tires being "fairly slick" is not a bad thing.

The fact that your time is almost double that of the KOM (that is a massive difference, even if he has stickier tires) probably means that you are nowhere near pushing your traction limit.

The only piece of advice I can give you other than "get used to riding fast down hills" is to take the largest-radius path through the curve. This means starting on the outside, coming in to the inside through the middle of the curve, and then exiting on the outside.

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    Thanks for the answer! It's probably just that I'm not used to it, as you pointed out. Could you recommend some good, grippy/gummy road tires? – Jules Nov 1 '15 at 22:04
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    No, not really :) I'd guess that the stickiest tires would be hardcore road racing tires. Tires biased towards touring are going to be less sticky, because lifespan is an issue. – BSO rider Nov 1 '15 at 23:31
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    note that tread on your tyres doesn't make them less slippery, unless you're riding in mud. Tread is for dirt and to prevent aquaplaning which isn't a big deal with skinny tyres. – stib Nov 12 '15 at 11:28
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Keep in mind that indoor use rollers can upload to Strava as if they were a properly done activity. This implies that downhill segments are being taken easily by that means, since they do not account for the risk. Also, aiming for downhill segments is pretty much setting yourself for a crash, people have already died because of that.

In any case, even if the KOM is genuine, your bike might not be the same as the people riding faster, who may be in expensive machines with top notch wheels, tyres, brakes and a geometry more suited for descent. In the case of going uphill it is the same, people may have a better suited machine, but the risk of trying to match them is considerably smaller. Also the rider can be short and heavy, with a lower centre of gravity and whatnot. Some may take risks and go into the opposite lane, or a certain KOM may have been taken with closed road during an event.

Gauging the speed at which you can take on a turn is tricky, even your tyre pressure can influence that. Try to get information on the best descending techniques and practice if you really want to get better. Your equipment, position on the bike, and weather will influence what is the maximum speed you can achieve on a given turn, and with practice you will get closer to that maximum. But let me remark that it is not a good idea to go for downhill KOMs. As the velominati rules put it, your confidence going downhill increases until it drops all of a sudden.

  • Care to say why the -1 anonymous down voter? – gaurwraith Aug 15 '16 at 15:30
  • Wasn't me, but I guess that your answer is unrelated to the question at the start. Question is specifically about riding a curve as fast as someone with the KOM. Trainer rides don't get KOMs. +1 for quoting a relevant rule though. – Criggie Aug 16 '16 at 7:14
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    Trainer rides do get KOMs if the user uploads them as a normal activity @Criggie. If nobody cares and the ride is not flagged you'll never know. My answer was roughly do not aim to get as fast as the KOM on a downhill, you never know who is riding, it may be a professional, it may be someone riding behind a car, or on closed roads, or blatant cheating. Strava doesn't allow to mark a downhill segment as a goal for a reason. Even practice is not enough, Froome would not get on the top bar and spin down at 90 kph on my bicycle. – gaurwraith Aug 16 '16 at 7:30
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    Some trainers, not all, of course. Like Bkool and others with software where you upload a course or track and follow it, they produce a file with the timestamps that the trainer is recording, and Strava accepts them as a genuine activity. I've had people riding seconds faster than me on the same moment I was on the road alone, and they were from other country, talked to them and they told me it was a trainer ride, that's how I noticed. – gaurwraith Aug 16 '16 at 7:42
  • Thank you for the info on trainers - I was unaware of that. – Criggie Aug 16 '16 at 7:55

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