# Tyre pressures in long distance events



## Jerry Atrik (15 Sep 2019)

Really dumb question .
On long distance events with a change of routes from tarmac to gravel to tracks etc do you change your tyre pressure accordingly ?
Having done battle on the beach earlier this year I had to deflate my tyres real low to get round .
But if your racing one of the big events that cover all terrain do you waste time by adjusting or leave them pumped solid and take the rough with the smooth ?


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## Heltor Chasca (15 Sep 2019)

I have a Lezyne mini floor pump with a gauge. Or you could just use a pressure gauge and pump separately. 

On off road tours I have reduced pressure off road then pumped them up again on the road.

I like to think the 5 minute faff doing this saved me that on the road and made the off road bit safer and more pleasant.


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## DCLane (15 Sep 2019)

Conversely - I don't change tyre pressures on the 200-1400km events I've done; 25mm tyres 110psi front, 115psi rear when fully kitted.

_If_ it's got some 'off-roady' bits I might use a different bike with 28mm tyres - which would be at 90psi.

But I don't change the tyre pressure just for the event. Why would you? It takes additional time and potentially adds a risk. Pump before the start and leave alone!


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## Ming the Merciless (15 Sep 2019)

Never have them pumped solid that'll slow you down on the road as well. At the start of a 400km or longer event I tend to pump my tyres up to the upper limit of what I find comfortable. Then I let them naturally lose air over the course of the event. They will hit a perfect balance of speed and comfort during the event, you'll know when. I generally won't top up till they either start feeling sluggish or not so secure when cornering.

Multi surface really depends how different the surfaces are. Gravel doesn't generally need much adjustment but something rough you may want to drop them. But this all depends how long the section is. A km, hardly worth it, changing to 100km of gravel, or more commonly dirt in the UK, worth getting the pressures right for you.

Most riders also have too much pressure in their front tyre. On my 32mm I run 70 psi rear and around 55 psi front. Speedy and comfortable.


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## Jerry Atrik (15 Sep 2019)

I’m thinking of doing the Tuscany trail next year on 650b tyres and probably over stressing the point already


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## frank9755 (4 Oct 2019)

Jerry Atrik said:


> Really dumb question .
> On long distance events with a change of routes from tarmac to gravel to tracks etc do you change your tyre pressure accordingly ?
> Having done battle on the beach earlier this year I had to deflate my tyres real low to get round .
> But if your racing one of the big events that cover all terrain do you waste time by adjusting or leave them pumped solid and take the rough with the smooth ?



It's a vaild question which has been discussed, but no, nobody I am aware of does it. Pumping up tyres when you don't have to is soul-destroying and stopping just take out air is a form of faffing! 

I've not encountered any surfaces where taking out air would make that much of a difference to traction, like your beach. For example in the TCR this year, the hard bits of CP2 were unrideable for virtually everyone, not because you couldn't get enough traction but because they were so steep that you needed to put out more power for a longer period than people were able to. Soft, fat tyres wouldn't have helped. 

I am conscious of my tyre pressures and aware that they will fall over a long event. I start with them at the top of the inflation range and put more air in when they are too soft, maybe after a week. But towards the end of something like the TCR I would not bother, I'd just keep riding even if I could feel the rim hitting the road occasionally on bumps!


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## dave r (4 Oct 2019)

I've never bothered much with tyre pressures, if I'm riding and the tyre feels a bit soft I'll put some air in it, if I squeeze the tyre between thumb and forefinger and it feels hard enough that will do and thats it.


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## steveindenmark (24 Oct 2019)

Try it at home for weeks on end on different surfaces. You will find a pressure you like. I dont know anybody who stops to change pressures. It just wastes time.


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## ianrauk (24 Oct 2019)

Steve's right. No ones ever stops to change tyre pressures. Well no one I know anyway.


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## frank9755 (29 Nov 2019)

The TCR route has been announced for next year and it includes some sections of pave near Roubaix. Some people have talked of dropping their tyre pressures for those sections. I suspect they might not bother, though!


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## Heltor Chasca (29 Nov 2019)

Does anyone use an online tyre pressure calculator or app? I had a look yesterday but didn’t come up with much. A couple I tried come up with ludicrously high pressures for the rear and very low for the front.


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## jiberjaber (29 Nov 2019)

Heltor Chasca said:


> Does anyone use an online tyre pressure calculator or app? I had a look yesterday but didn’t come up with much. A couple I tried come up with ludicrously high pressures for the rear and very low for the front.


A long time ago when I first started riding I did look around but the faff of trying to work out the % split front and back of weight then keeping the tyres at that pressure plus then the ride terrain changing to no real objective measurement I gave in and just concentrated on what was comfortable & worked for me... 

So I'm of the same opinion as DCLane and Frank here... just fill em up to where you would like them to be and then ride. The only time I have topped up on a long one has been if there was a non natural pressure loss (visitation rather than just leakage over time). 
I topped up on LEL once at Brampton on the way up IIRC
I didn't top up on PBP out on 60psi back on around 40psi and on my recent trip around France three times - all around the 600km between top ups I think (I certainly had 2 visitations I noticed on the France tour and was carrying a lot more weight than I would usually, same tyres as PBP).


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## Ajax Bay (11 Feb 2020)

See this BQ article. I think @DCLane is lighter than me so surprised he runs such high pressures. I look for some '(not very) rough stuff' during every audax and certainly don't stop to reduce pressures.


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## Mike Ayling (22 Feb 2020)

How much time would you lose inflating/deflating in your event?


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## Shreds (13 Jun 2020)

Never bothered; wastes too much time!


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## frank9755 (10 Jul 2020)

Mike Ayling said:


> How much time would you lose inflating/deflating in your event?



It's not so much the time - although the time is a factor as every time you stop you lose a km plus the time you are stopped for - but it is more the mental effort of doing it. In a long race, you don't want to stop if you don't have to as it breaks up your rhythm


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## Ming the Merciless (10 Jul 2020)

Heltor Chasca said:


> Does anyone use an online tyre pressure calculator or app? I had a look yesterday but didn’t come up with much. A couple I tried come up with ludicrously high pressures for the rear and very low for the front.



This one works on the 15% drop principle

http://www.dorkypantsr.us/bike-tire-pressure-calculator.html


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## Ajax Bay (10 Jul 2020)

Heltor Chasca said:


> ludicrously high pressures for the rear and very low for the front.


It might be worth you actually doing the bathroom scales test for each wheel (sitting on saddle and hands on hoods) to see what the two loads are. Then just use the graph.


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## rogerzilla (12 Jul 2020)

I started last year's Dunwich Dynamo with about 180psi in the rear, and finished with about 130psi. The joys of latex tubes on a 9 hour event!


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## frank9755 (16 Jul 2020)

rogerzilla said:


> I started last year's Dunwich Dynamo with about 180psi in the rear, and finished with about 130psi. The joys of latex tubes on a 9 hour event!



Why did you want 180psi, and how did you get it in?


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## rogerzilla (16 Jul 2020)

So there was enough left to resist pinch punctures by the end. We had a track pump on the coach to London.

Latex tubes can lose half the air in 24 hours. They are sometimes worth it, though.


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## Ajax Bay (16 Jul 2020)

rogerzilla said:


> They are sometimes worth it, though.


When? (Assume you mean TTs or racing but choosing not to use tubs.) For TTs now the best tyres (for the lowest RR) are TL. My daughter's team supplies her Vittoria-corsa-speed-g2 and the National 100 mile TT beckons in August. But I guess that's off topic: it's not really 'long distance'.


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## rogerzilla (16 Jul 2020)

Any event where you want to increase speed or minimise energy expenditure, really. I don't have the inclination to go tubeless as it's a massive faff, and very messy if you need to fix a puncture out on the road (assuming you use sealant).

Tubs, FWIW, are higher-friction than tubed tyres, all other things being equal. But all other things are not equal, and tubs benefit from MUCH lighter rims, work at almost any pressure you like and tend to have - yes - latex tubes. The faff factor is enormous.


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## huwsparky (2 Aug 2020)

rogerzilla said:


> I started last year's Dunwich Dynamo with about 180psi in the rear, and finished with about 130psi. The joys of latex tubes on a 9 hour event!


You were losing a massive amount of watts at that pressure. You'd be absolutely staggered if you knew quite how much I suspect. Let alone how horrible riding a bike on the road at 180psi feels.


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## Ajax Bay (2 Aug 2020)

huwsparky said:


> You were losing a massive amount of watts at that pressure.


Please could you explain why running tyres (assume 23s) at 180psi (which I think is bonkers too) loses a rider "massive amounts of watts".
Compared to watt?
https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison


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## rogerzilla (2 Aug 2020)

Easiest run of my eight so far.


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## huwsparky (2 Aug 2020)

Ajax Bay said:


> Please could you explain why running tyres (assume 23s) at 180psi (which I think is bonkers too) loses a rider "massive amounts of watts".
> Compared to watt?
> https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison


As soon as you pump a tyre above a certain point it falls off a cliff effectively in terms of efficiency. Reason being the bike and the rider has to absorb that energy rather than deflection in the tyre. To know what that point is you need to factor in what the tyre measures out to on the rim, road surface, total weight (rider + bike), also the speed at which the bike will be travelling. Much better off being a bar under optimum than a bar over. For my TT setup with me at 70kg for the surfaces I ride on about 67 - 70psi is the fastest setup. Changing tyres tubes and running them at optimum pressures has saved me circa 20w+ @ 45kph. 20w for less than £100


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## huwsparky (2 Aug 2020)

rogerzilla said:


> Easiest run of my eight so far.


So let me get this right, you're of the opinion that running these pressures is worthwhile just so you can run Latex tubes? I'm surprised your teeth stayed in . The days of running these pressures are long gone buddy.


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## Ajax Bay (2 Aug 2020)

huwsparky said:


> As soon as you pump a tyre above a certain point it falls off a cliff effectively in terms of efficiency. Reason being the bike and the rider has to absorb that energy rather than deflection in the tyre. To know what that point is you need to factor in what the tyre measures out to on the rim, road surface, total weight (rider + bike), also the speed at which the bike will be travelling. Much better off being a bar under optimum than a bar over. For my TT setup with me at 70kg for the surfaces I ride on about 67 - 70psi is the fastest setup. Changing tyres tubes and running them at optimum pressures has saved me circa 20w+ @ 45kph.


Hope you don't mind if I probe some of this, Huw. Some reputable links to reinforce your answers would be great.
_As soon as you pump a tyre above a certain point it falls off a cliff effectively in terms of efficiency._
You're making this up, depending what you mean by 'falling of a cliff' 'effectively' and 'efficiency'. Beyond a certain pressure a tyre's rolling resistance plateaus. Have you a graph to share?
"As pressures increase, tires roll faster, but the performance levels off at a certain pressure. Beyond this point, higher inflation brings only negligible performance improvements." [ Heine, J. and M. Vande Kamp, 2006: The Performance of Tires. BQ Vol. 5, No. 1, p. 1. ]
_the bike and the rider has to absorb that energy rather than deflection in the tyre._
You've not mentioned this 'energy' before (but I understand the 'suspension (body) losses' idea you tried to share).
_To know what that point [optimum pressure] is you need to factor in what the tyre measures out to on the rim, road surface, total weight (rider + bike), also the speed at which the bike will be travelling. _
And the formula is? Actual tyre width: check. What metric can you use for road surface? Load on each tyre (NB different front and rear): check. How much do each of those factors separately contribute, or are you making this up?
_Much better off being a bar under optimum than a bar over._
Why? More likely to get snake bites, so better to be over than under.
_For my TT setup with me at 70kg for the surfaces I ride on about 67 - 70psi is the fastest setup._
How do you know? Both wheels? 32mm wide tyres! On a TT bike? Do your competitors buy in to this outlying philosophy?
_Changing tyres tubes and running them at optimum pressures has saved me circa 20w+ @ 45kph._
What were the previous tyres, tubes and what were the new ones? I bet that will account for any power saving that you purport to measure. If you were running previous tyres at (too) low pressures then running the new (better) ones at optimum (15% drop) pressure would obviously offer rolling resistance reductions.


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## huwsparky (2 Aug 2020)

@Ajax Bay people still thought 20mm tyres pumped up to 200psi were fast in 2006 buddy...


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## Ajax Bay (3 Aug 2020)

Thank you for that historic insight to track cycling though a simple answer to any of my questions would have been attractive and to your credit. And on the road your tyre width on your TT bike is 32mm then?  Which would fit fine with your avowed 70psi rear, but @ 45kph would result in expending an unattractive amount of energy overcoming the increased drag.
I thought you'd appreciate re-reading some of your posts from yesteryear:


huwsparky said:


> I don't generally believe most things I read with regard to improving cycling performance etc, as it's usually to try and sell something.


Although I guess wider tyres at lower pressures is not really a useful 'selling' point: air is free.


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## Ajax Bay (3 Aug 2020)

And this, with regard to being able to determine what the optimum pressure in your TT bike tyres is:


huwsparky said:


> It'll be very difficult to accurately measure a wheels performance. For example, say if you rode a set route at a set power and recorded a time. Even if you were to go back and do exactly the same on a different wheelset it would be almost impossible to compare accurately due to small changes in wind speed/direction, slight difference in tyre pressure, not riding over the exact same piece of tarmac etc... All these little things would make a difference and make any test not very accurate!


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## huwsparky (3 Aug 2020)

Ajax Bay said:


> And this, with regard to being able to determine what the optimum pressure in your TT bike tyres is:


Optimum pressure is optimum pressure. The only difference with it being a TT bike front and rear will be the same as weight distribution is 50-50. Obviously I'm a lot more fussy with what pressure I run in that case as it matters.


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## cougie uk (3 Aug 2020)

rogerzilla said:


> So there was enough left to resist pinch punctures by the end. We had a track pump on the coach to London.
> 
> Latex tubes can lose half the air in 24 hours. They are sometimes worth it, though.


What tyres are they ? Have you checked the Max pressure for the tyre (and the rim for that matter)

I'm finding things much better with lower pressures than I used to put in - on the advice of a Continental tyre mechanic. Very few incidents.


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## Ajax Bay (3 Aug 2020)

huwsparky said:


> Optimum pressure is optimum pressure.


How can anyone disagree with that?


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## huwsparky (3 Aug 2020)

This calculator is going to be the most comprehensive there is. Try it out. You HAVE to know what your tyre measures out to on the rim though. I race on 23mm but they measure out to over 26mm on the rims I use.
https://info.silca.cc/silca-professional-pressure-calculator


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## huwsparky (3 Aug 2020)

@Ajax Bay they guy who who developed this is a guy called Josh Poertner. Well worth listening to what he has to say with regards to pressures and generally saving a few watts here and there which I appreciate 99% of people who cycle won't really care about.

I can actually validate my savings but I can't go into it here, it will likely break me. But i can assure you I've saved around 20w @27mph, i appreciate people don't generally ride at 27mph but there's a lot of little savings to be made for everyone, many of them for little outlay.


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## Ajax Bay (3 Aug 2020)

Rolling-resistance-and-impedance





Green is 'brand new asphalt, yellow = coarse intermediate asphalt, and red = machine roughened concrete (simulated cobbles)


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## huwsparky (3 Aug 2020)

You see what i mean by tyres effectively falling off a cliff beyond a certain point? We have hardly any smooth roads where i live, it's all chip and seal which as we all know when you transition to one from another travelling at the same speed gets either very easy or very hard depending on which way you're transitioning.


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## matticus (3 Aug 2020)

_slight _thread diversion ... do you really live in Llangrannog?? What a delightful (and tiny) place to live! I don't recall the roads between there and LLandysul being too bad. Perhaps bad for Wales, but that means better than almost all of England


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## huwsparky (3 Aug 2020)

matticus said:


> _slight _thread diversion ... do you really live in Llangrannog?? What a delightful (and tiny) place to live! I don't recall the roads between there and LLandysul being too bad. Perhaps bad for Wales, but that means better than almost all of England



Yes, just outside, we're very lucky really. We get enough climbing in down here!! Surfaces are mostly chip and seal, there's stretches of better surface but generally i don't really ride it due to traffic, especially this time of year.


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## Ajax Bay (3 Aug 2020)

Thank you. My daughter will be riding the National 100 miles for Royal Wootton Bassett in a fortnight. Her wheels are
Vittoria Corsa Speed G+ 2.0 (TLR), 25mm wide (measured) and weighing 70kg (bike, rider and hydration) she'll be riding them at 85psi, aiming for as close as she can manage to 4 hours.


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## huwsparky (3 Aug 2020)

Ajax Bay said:


> Thank you. My daughter will be riding the National 100 miles for Royal Wootton Bassett in a fortnight. Her wheels are
> Vittoria Corsa Speed G+ 2.0 (TLR), 25mm wide (measured) and weighing 70kg (bike, rider and hydration) she'll be riding them at 85psi, aiming for as close as she can manage to 4 hours.


Definitely the best tyre for the job. With latex tubes or tubeless? Good luck!


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## Ajax Bay (5 Aug 2020)

Tubeless - team supplied. Think her last long (100+) trial was using 5000s and latex, but she's had these/the bike/the wheels since January.


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