The chip seal in NZ sucks. Go 90.

Agreed. Keep the pressure on the low side for your weight.

How much do you weigh?

I'd agree with this unless you're a really big unit. The road isn't as bad as it used to be - town is fine, and a lot of the road out to Reparoa (the turnaround) was resurfaced just in time for the race last year. It's a hell of a lot better than the roads where I live a few hours south of Taupo. I'm not racing this year due to a new baby - have an awesome day, and make sure you bring gear for all weathers!

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Will be probably 80/81 with cycling gear on

80/81 what?

KGs.

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What pressure do you normally use?
90-100psi is more than enough on 25mm tyres at that weight regardless of the road surface.
Also what's your internal rim width.
I generally ride either 25mm Continental GP4000s on 19mm wide Swiss-Side rims on the tri bike or 25mm Michelin Pro4 SC on 15mm Mavic rims on the road bike. I use similar pressures on both and those pressures are usually:
rear wheel = 90psi to 100psi
front wheel = 80psi to 85psi.

I ran close to this there last year. Believe I went 85 in the rear and 80 up front. I weigh 75kg.

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-Brad Williams
Website | Twitter: @BW_Tri |Instagram: @BW_Tri | Strava | Co-Founder & Coach at: KIS Coaching
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I'm running Vittoria Evo CXII tubulars on Hed Stinger wheels (the wide rims), 23mm front 25mm rear. I weigh 71kg what would you recommend for my pressure? I was going to run 95 rear 90 front

Not well versed in Tubulars, so not sure if it is different for them. But if they were clinchers and with your weight I would run close to what I recommended above, if not a little less.

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-Brad Williams
Website | Twitter: @BW_Tri |Instagram: @BW_Tri | Strava | Co-Founder & Coach at: KIS Coaching
Partnered with: Zoot Sports | Precision Fuel &Hydration | ISM

I'd go with 80-90psi as the roads are pretty rough and while I'm not a serious data geek there is some evidence that states the benefits of comfort you'll gain out weigh the friction caused by surface area in contact with the road. If I were you I'd also go with 25mm up front and 25mm (28mm if you can) in the rear tyres. That way you could easily run around 80-90psi as they do in the Paris Roubaix.

No kidding. The year I did IMNZ it was 3C and foggy at race start. I froze for the first lap of the bike.
By the time I was only my final lap of the run it was 27C and I was getting a sunburn.

x2...make that x1000...

I raced there a couple years ago and I didn't find the roads to be that bad. Switching over to latex tubes for race day also seems to soften the feel of the road, so the chip seal didn't bother me that much.

 
Pissed down for 2 days straight - lake is cooling nicely.

;)

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Where I live, the new chipseal is the worst! The older stuff gradually gets worn down.

If it's rough chipseal, 25c GP4000 and 180 lb full up weight, I think 80 psi would suffice. Maybe less if there aren't potholes and rocks to worry about.

I have switched tubes as well so we'll see how that goes!

I'm using 19mm rims so might go something along the lines you use. Thanks

Great thanks for the advice

Bah. It was lovely in Kinloch last weekend. Just about right.

Is Taupo generally a slow lake to swim in, or is it just me - I always seem to go faster in the Blue Lake in Rotorua.

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Swim. Overbike. Walk.

The roads at IMNZ are freaking horrible.

Whatever you ride on race day (on your 25mm's) ride 10-20 PSI less.

Before race day, don't to an easy ride along the waterfront, ride up the Napier/Taupo hill. Know it, or you will be in the big ring and go "Oh FK" and be stuck at 40RPM for 5 minutes.

also, if you can, get a ride to the race track. Ride 20km out and 20km back. You need to know that hill in both directions, and also the crappy road for a while. That will convince you to ride 10-20 PSI lower than normal.

You will see speeds lower than you're used to, but don't worry. If you ride hard on hard tires, you bike split will be ok, but your legs will be fried from all the vibration. Give up a couple of minutes on the bike so you can actually run the marathon, without crying for your mommy.

On 25's you're probably good with 90-95 PSI

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

Also didn't find the roads bad at all last year.

Rode 9min faster at Taupo than Kona so conditions dependant it really isn't that bad.

In saying that 90psi was about the mark I went with in both wheels. Enve 8.9 with 23 Continental gp4000IIS

 
It's dropped since last weekend, 2 days of cold weather & rain will do that.

How are you gauging 'faster' between the two? Just on feel? I often think its like riding a bike in the dark - you always feel like you're going faster. Blue Lake is the same, you can't see a thing compared to seeing the bottom the whole way in Taupo.

SB.

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I gauge it on gps (which we all know is fabulously accurate in water) and time. I was 5 mins slower at Taupo '15 compared with Roto '15 a week later. I'm pretty sure I didn't get that much training effect from the first half.

I dunno. Maybe I was more keyed up for Rotorua.

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Swim. Overbike. Walk.

Awesome, thanks for the advice

Surely the roads can't be that bad. What are you comparing them to? I'm use to riding on pretty rough roads at home, on about 105 psi. I was thinking I might drop to 95 just in case.

What does Tom A's crr data show with psi and rolling resistance? I thought I could remember a really good chart he posted but can't find it.

Regarding the impact of surface quality - he's found that there's a break point where road roughness is a far bigger factor than anything else. Rolling resistance drops with pressure increase until you hit that break point and then resistance increases significantly with added pressure. The conclusion was that you're much better off erring on the low side when it comes to tyre pressure.

the thing isn't the speed vs pressure that's important. It's the hammering your legs take on a rough road. I lab test will find the optimum pressure for any surface, to get max speed, but that won't tell you how it will affect your body.

180km on those roads just simply beats you up. 110 psi might get you to T2 5 minutes faster than 90 psi, but you'll run like you're on clay quads and lose 10 minutes. to top that off, virtually the entire run is on concrete sidewalks. Very little relief on asphalt for example.

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

I did it last year on 23 mm 4000IIS at 95psi.

The roads are a bit rough but it's no issue in the grand scheme of things.

There are quite defined truck marks on the road, where it is smoother. Go on those and you'll pick up some easy gains.

Kent

The 180k bike does beat you up, but on the 3 loop run, probably 26k to 28k of it (~65%) is on chipseal asphalt - so not that bad :)

Most of the outbound loop all the way to Four Mile Bay is on asphalt, and probably about a third is on asphalt on the way back - you hit the concrete at that little crossover by Chad, and then it's concrete path pretty much all the way from Two Mile Bay to almost the trout on Lake Terrace before hitting the asphalt again.

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180km on those roads just simply beats you up. 110 psi might get you to T2 5 minutes faster than 90 psi, but you'll run like you're on clay quads and lose 10 minutes. to top that off, virtually the entire run is on concrete sidewalks. Very little relief on asphalt for example.[/quote]

The 180k bike does beat you up, but on the 3 loop run, probably 26k to 28k of it (~65%) is on chipseal asphalt - so not that bad :)

Most of the outbound loop all the way to Four Mile Bay is on asphalt, and probably about a third is on asphalt on the way back - you hit the concrete at that little crossover by Chad, and then it's concrete path pretty much all the way from Two Mile Bay to almost the trout on Lake Terrace before hitting the asphalt again.[/quote]
Doh,
I only did IMNZ when it was a 2 lap run, not the more recent 3 lap version. My bad. I just remember the concrete sidewalks destroying my arthritic hips after the pounding they took on the bike.

Still, IMNZ road surfaces remind you the difference between the lab and the real world.

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

Oh man.... I did this race a few years back, and my teeth rattled for about a week!!!


Seriously though - it was a great day.

God don't ever do Ironman australia.

You must be traumatised, as there's not that much concrete at all, and the year you did it (2 laps) there'd of been even less as a percentage than the current course, because you ran out to Mahuta Drive and back, which is effectively all tar seal as you're on the highway.

That said, it's a tough run, you see how tough when you sit out on a kayak looking back at shore and see the elevation changes of the course.

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A friend of mine lived in Taupo for a number of years. She trained on the course year round. She routinely rode with 160-180 PSI tires! One day I saw here pumping up before a ride. She lifted the T-Handle of the pump all the way up, leaned on it, took her feet off the ground, then bounced up and down until the handle reached the bottom. I queried why and she said "It says 180psi on the side of the tire". Unsurprisingly, she had a bad habit of falling off any time she tried to corner in the rain. I feel sorry for the person that bought her used bike.

I'd be surprised if she has any sensation left in her nether regions after years of riding Taupo roads at 180PSI. Or any fillings left.

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"