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Tyre pressure question
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So I switched to tubs 6 months ago and have been tinkering around with tyre pressure. I did a bit of research, but that just totally confused me. People I train with and on forums saying they run their tubs anything from 80 psi up to 160 psi. An ex Olympian cyclist, Matt Illingworth mentioned he used to run his at 160, but 140 psi would be OK, with my Vittoria Corsa Speed G+. So I've been racing with them between 130 and 140 and they've felt good. The road surfaces are generally good. I had a chat with Jack Bobridge (Olympian & TDF) after a race (OD, he did the duathlon) and mentioned what tyre pressure I was running, he looked at me like I was mad! Anyway I had a sprint at the weekend and decided to stick them up to 150psi, excellent roads, but I was very sluggish on the bike. I really struggled. I could have just had an off day, but bike didn't feel right. I'm thinking of dropping them down to 120ish but not sure. So what's the science behind tyre pressure? How can I find optimum tyre pressure for me? I'm 160 lbs. All the roads I ride are on pretty good quality and I never feel like I've getting bounced around.

Note - I'm aware inflating to 150psi was probably a dumb ass move, a bit of an experiment if you like.

I'm running 23mm Vittoria Corsa Speed G+ tubs on Zipp 900 disc and 808 front
Last edited by: zedzded: Apr 16, 18 20:29
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Re: Tyre pressure question [zedzded] [ In reply to ]
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Depends on your tire size, weight, and intended road surface. A track cyclist may opt for a narrow tubular tire at super high pressure because the surface is smooth and there are no variables like having to corner in the rain where you want a bigger contact patch to the ground.

On the flip side, you have tour pros running 27-30 mm tubulars at 55-65 psi at Paris Roubaix due to all the cobbles, which are potentially wet.

Moving to cyclocross and you've got to deal with roots, rocks, mud, and off camber cornering and they run 33 mm tubulars at 20-25 psi.

Personally, I only use my set of 202 tubulars for climbing only bike races. On average roads, I run 23 mm vittorias at 85-90 psi and 95-100 psi on silky smooth roads. I do plan to move to 25 mm tubular tires, and would likely drop pressure to 80-85 and 90-95 respectively. I'm 155-160 pounds
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Re: Tyre pressure question [zedzded] [ In reply to ]
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zedzded wrote:
So I switched to tubs 6 months ago and have been tinkering around with tyre pressure. I did a bit of research, but that just totally confused me. People I train with and on forums saying they run their tubs anything from 80 psi up to 160 psi. An ex Olympian cyclist, Matt Illingworth mentioned he used to run his at 160, but 140 psi would be OK, with my Vittoria Corsa Speed G+. So I've been racing with them between 130 and 140 and they've felt good. The road surfaces are generally good. I had a chat with Jack Bobridge (Olympian & TDF) after a race (OD, he did the duathlon) and mentioned what tyre pressure I was running, he looked at me like I was mad! Anyway I had a sprint at the weekend and decided to stick them up to 150psi, excellent roads, but I was very sluggish on the bike. I really struggled. I could have just had an off day, but bike didn't feel right. I'm thinking of dropping them down to 120ish but not sure. So what's the science behind tyre pressure? How can I find optimum tyre pressure for me? I'm 160 lbs. All the roads I ride are on pretty good quality and I never feel like I've getting bounced around.

Note - I'm aware inflating to 150psi was probably a dumb ass move, a bit of an experiment if you like.

I'm running 23mm Vittoria Corsa Speed G+ tubs on Zipp 900 disc and 808 front
Wow, if you ride those sorts of pressures on roads that are anything less than truely spectacular and have never felt you've been bounced around, it's because your comfort calibration is way out of whack!
The good news is that you should be able to dramatically drop your pressure without any significant increase in resistance, and quite possibly an decrease. And, the comfort difference should be a revelation. I know no reason to run at anywhere near those pressures (unless perhaps you're on 18mm tyres).

I weigh quite a bit more than you, typical range 80-83kg. I ride 23mm tyres at 80-85 front / 95-105 rear on narrow rims. I ride 25mm tyres at 75-80 front / 85-95 rear on narrow rims and about 5psi lower on wide rims. I could go a bit lower but don't like them to feel squishy when climbing out of the saddle.

Based on Tom A and Silca's testing I believe you're much better off to err low than high. There is a small reduction in RR with increased pressure until a certain point beyond which it increases dramatically with additional pressure. It seems very likely that you're beyond this point and losing speed due to excessive pressure.
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Re: Tyre pressure question [Ai_1] [ In reply to ]
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Ai_1 wrote:
zedzded wrote:
So I switched to tubs 6 months ago and have been tinkering around with tyre pressure. I did a bit of research, but that just totally confused me. People I train with and on forums saying they run their tubs anything from 80 psi up to 160 psi. An ex Olympian cyclist, Matt Illingworth mentioned he used to run his at 160, but 140 psi would be OK, with my Vittoria Corsa Speed G+. So I've been racing with them between 130 and 140 and they've felt good. The road surfaces are generally good. I had a chat with Jack Bobridge (Olympian & TDF) after a race (OD, he did the duathlon) and mentioned what tyre pressure I was running, he looked at me like I was mad! Anyway I had a sprint at the weekend and decided to stick them up to 150psi, excellent roads, but I was very sluggish on the bike. I really struggled. I could have just had an off day, but bike didn't feel right. I'm thinking of dropping them down to 120ish but not sure. So what's the science behind tyre pressure? How can I find optimum tyre pressure for me? I'm 160 lbs. All the roads I ride are on pretty good quality and I never feel like I've getting bounced around.

Note - I'm aware inflating to 150psi was probably a dumb ass move, a bit of an experiment if you like.

I'm running 23mm Vittoria Corsa Speed G+ tubs on Zipp 900 disc and 808 front

Wow, if you ride those sorts of pressures on roads that are anything less than truely spectacular and have never felt you've been bounced around, it's because your comfort calibration is way out of whack!
The good news is that you should be able to dramatically drop your pressure without any significant increase in resistance, and quite possibly an decrease. And, the comfort difference should be a revelation. I know no reason to run at anywhere near those pressures (unless perhaps you're on 18mm tyres).

I weigh quite a bit more than you, typical range 80-83kg. I ride 23mm tyres at 80-85 front / 95-105 rear on narrow rims. I ride 25mm tyres at 75-80 front / 85-95 rear on narrow rims and about 5psi lower on wide rims. I could go a bit lower but don't like them to feel squishy when climbing out of the saddle.

Based on Tom A and Silca's testing I believe you're much better off to err low than high. There is a small reduction in RR with increased pressure until a certain point beyond which it increases dramatically with additional pressure. It seems very likely that you're beyond this point and losing speed due to excessive pressure.

So just to join those dots in case it isn't obvious.The method is to start with a high pressure and test that you feel that bouncing. A bike with too much high pressure in the tires will skip up or to side of every small obstruction. obviously you can't do this on the whole course so it's up to you where you do it but that's another question. Then you reduce the pressure in small increments and test ride until that skittering feeling goes away. That should be where you want to be. You aren't losing energy skipping and jumping over stuff but also the pressure isn't any lower than it needs to be and you aren't losing energy dragging a tire around that's too soft. At least that's how I see it. My brother just puts as much air in as he can and hopefully not blow up the tire.
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Re: Tyre pressure question [OddSlug] [ In reply to ]
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OddSlug wrote:
Ai_1 wrote:
zedzded wrote:
So I switched to tubs 6 months ago and have been tinkering around with tyre pressure. I did a bit of research, but that just totally confused me. People I train with and on forums saying they run their tubs anything from 80 psi up to 160 psi. An ex Olympian cyclist, Matt Illingworth mentioned he used to run his at 160, but 140 psi would be OK, with my Vittoria Corsa Speed G+. So I've been racing with them between 130 and 140 and they've felt good. The road surfaces are generally good. I had a chat with Jack Bobridge (Olympian & TDF) after a race (OD, he did the duathlon) and mentioned what tyre pressure I was running, he looked at me like I was mad! Anyway I had a sprint at the weekend and decided to stick them up to 150psi, excellent roads, but I was very sluggish on the bike. I really struggled. I could have just had an off day, but bike didn't feel right. I'm thinking of dropping them down to 120ish but not sure. So what's the science behind tyre pressure? How can I find optimum tyre pressure for me? I'm 160 lbs. All the roads I ride are on pretty good quality and I never feel like I've getting bounced around.

Note - I'm aware inflating to 150psi was probably a dumb ass move, a bit of an experiment if you like.

I'm running 23mm Vittoria Corsa Speed G+ tubs on Zipp 900 disc and 808 front

Wow, if you ride those sorts of pressures on roads that are anything less than truely spectacular and have never felt you've been bounced around, it's because your comfort calibration is way out of whack!
The good news is that you should be able to dramatically drop your pressure without any significant increase in resistance, and quite possibly an decrease. And, the comfort difference should be a revelation. I know no reason to run at anywhere near those pressures (unless perhaps you're on 18mm tyres).

I weigh quite a bit more than you, typical range 80-83kg. I ride 23mm tyres at 80-85 front / 95-105 rear on narrow rims. I ride 25mm tyres at 75-80 front / 85-95 rear on narrow rims and about 5psi lower on wide rims. I could go a bit lower but don't like them to feel squishy when climbing out of the saddle.

Based on Tom A and Silca's testing I believe you're much better off to err low than high. There is a small reduction in RR with increased pressure until a certain point beyond which it increases dramatically with additional pressure. It seems very likely that you're beyond this point and losing speed due to excessive pressure.


So just to join those dots in case it isn't obvious.The method is to start with a high pressure and test that you feel that bouncing. A bike with too much high pressure in the tires will skip up or to side of every small obstruction. obviously you can't do this on the whole course so it's up to you where you do it but that's another question. Then you reduce the pressure in small increments and test ride until that skittering feeling goes away. That should be where you want to be. You aren't losing energy skipping and jumping over stuff but also the pressure isn't any lower than it needs to be and you aren't losing energy dragging a tire around that's too soft. At least that's how I see it. My brother just puts as much air in as he can and hopefully not blow up the tire.
I think that method will likely leave you with higher than optimum pressure.
Have a look for the graphs on the Silca website. Links have been posted fairly frequently in various discussions here but I don't have it handy. Tom A has also discussed this topic quite frequently.
The plot of their findings shows a gradually reducing RR as pressure increases until a very defined break point where the RR starts increasing again. The lowest RR is therefore right at the break point. However, since the slope is much steeper after the breakpoint, it makes sense to err on the low side. The method you've outlined in the quote above depends on interpreting "bounce" by feel. I really don't think that's terribly useful. Everyone will interpret the feel differently and I expect those who've previously used very high pressures will end up remaining with excessive pressures.

If you weigh 70-80kg and use 23mm tyres, I'd be saying you should have figures like 85-105psi in mind for the rear and I always go about 10-15% lower at the front. If you weigh less, you should be able to go lower. If in doubt, try 90psi for a few training rides and see what you think. Don't forget, there's a difference between being fast and feeling fast!
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Re: Tyre pressure question [zedzded] [ In reply to ]
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zedzded wrote:
.....I had a chat with Jack Bobridge (Olympian & TDF) after a race (OD, he did the duathlon) and mentioned what tyre pressure I was running, he looked at me like I was mad!...
I meant to ask. I presume he thought you should be WAY lower, right? Did he mention a ballpark figure?
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Re: Tyre pressure question [Ai_1] [ In reply to ]
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You're absolutely right. I am probably over estimating my princess-and-pea sensitivity. I just think that the approach fits well with the graph you mentioned. Approaching the drop off from the high side would mean you hit the biggest contrast in the change of feeling. It seems to work for me and the times I've done it I end up in the range you mention. I would heavily qualify all that. Apart from anything else safety is important. For instance IMHO the higher pressure, skittery for those conditions, is more dangerous going into a fast corner with loose stuff. Seems to me it's more likely to slide on the top and skip side ways off that stuff when a more complaint tire will deform over more of that, bigger contact area and more likely to find a better surface. I'd also stay within the psi limits quoted by the tire manufacturer. If someone puts more psi in a tire than the people who design it and manufacture it suggest then it's a risk, pure and simple. Any approach is going to be an estimate without a science team behind you.
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Re: Tyre pressure question [zedzded] [ In reply to ]
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I run tubs, 23mm front and 25mm rear Vittoria EVO CX II's on HED stinger wheels on Australian roads.

Generally my 'go to' pressure is 95psi front and rear, if I was running a 23 in the back it would be at 100. For reference I weigh 75kg.

For rougher roads I'll drop the pressure by 5psi.

I used to race them at 130psi before I knew any better. They 'felt' fast, but after reducing pressure I was consistently getting slightly lower times on climbs near my local area for equivalent watts.
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Re: Tyre pressure question [zedzded] [ In reply to ]
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zedzded wrote:
So I've been racing with them between 130 and 140 and they've felt good. ...

I hope you are in the M45-49 age group

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Re: Tyre pressure question [zedzded] [ In reply to ]
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If you ride on regular roads (average usa roads in the dry), the most important variables are (1) your body weight and (2) the actual (not claimed) tire width after mounting.

For example, even with the same wheels and tires, a 105 lb woman should not be running anywhere near the same tire pressures as a 180 lb man.

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Re: Tyre pressure question [DarkSpeedWorks] [ In reply to ]
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To be fair, I think we've all been referencing weight and surface when recommending a pressure range.
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Re: Tyre pressure question [Ai_1] [ In reply to ]
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In this thread, yes.

But so many people talk to one another (here and other places) regarding "recommended" psi, and very very very few talk about modifying the psi by a lot for body weight differences.

Advanced Aero Top Tube Bento Packs for Road, Gravel, & Triathlon....Direct-mount and ZeroSlip strap-mount Speedpacks, all made in the USA.
DarkSpeedWorks.com....Reviews....Instagram....Facebook

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Re: Tyre pressure question [zedzded] [ In reply to ]
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zedzded wrote:
So I switched to tubs 6 months ago and have been tinkering around with tyre pressure. I did a bit of research, but that just totally confused me. People I train with and on forums saying they run their tubs anything from 80 psi up to 160 psi. An ex Olympian cyclist, Matt Illingworth mentioned he used to run his at 160, but 140 psi would be OK, with my Vittoria Corsa Speed G+. So I've been racing with them between 130 and 140 and they've felt good. The road surfaces are generally good. I had a chat with Jack Bobridge (Olympian & TDF) after a race (OD, he did the duathlon) and mentioned what tyre pressure I was running, he looked at me like I was mad! Anyway I had a sprint at the weekend and decided to stick them up to 150psi, excellent roads, but I was very sluggish on the bike. I really struggled. I could have just had an off day, but bike didn't feel right. I'm thinking of dropping them down to 120ish but not sure. So what's the science behind tyre pressure? How can I find optimum tyre pressure for me? I'm 160 lbs. All the roads I ride are on pretty good quality and I never feel like I've getting bounced around.

Note - I'm aware inflating to 150psi was probably a dumb ass move, a bit of an experiment if you like.

I'm running 23mm Vittoria Corsa Speed G+ tubs on Zipp 900 disc and 808 front

you are aware of this thread and all that has been done by Josh and Tom, right?

https://forum.slowtwitch.com/...%2C%20graph#p5996904
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Re: Tyre pressure question [rock] [ In reply to ]
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rock wrote:
I run tubs, 23mm front and 25mm rear Vittoria EVO CX II's on HED stinger wheels on Australian roads.

Generally my 'go to' pressure is 95psi front and rear, if I was running a 23 in the back it would be at 100. For reference I weigh 75kg.

For rougher roads I'll drop the pressure by 5psi.

I used to race them at 130psi before I knew any better. They 'felt' fast, but after reducing pressure I was consistently getting slightly lower times on climbs near my local area for equivalent watts.

Yeah I think that's why i ran them so high, they felt fast. But not on Sunday.
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Re: Tyre pressure question [dtoce] [ In reply to ]
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dtoce wrote:
zedzded wrote:
So I switched to tubs 6 months ago and have been tinkering around with tyre pressure. I did a bit of research, but that just totally confused me. People I train with and on forums saying they run their tubs anything from 80 psi up to 160 psi. An ex Olympian cyclist, Matt Illingworth mentioned he used to run his at 160, but 140 psi would be OK, with my Vittoria Corsa Speed G+. So I've been racing with them between 130 and 140 and they've felt good. The road surfaces are generally good. I had a chat with Jack Bobridge (Olympian & TDF) after a race (OD, he did the duathlon) and mentioned what tyre pressure I was running, he looked at me like I was mad! Anyway I had a sprint at the weekend and decided to stick them up to 150psi, excellent roads, but I was very sluggish on the bike. I really struggled. I could have just had an off day, but bike didn't feel right. I'm thinking of dropping them down to 120ish but not sure. So what's the science behind tyre pressure? How can I find optimum tyre pressure for me? I'm 160 lbs. All the roads I ride are on pretty good quality and I never feel like I've getting bounced around.

Note - I'm aware inflating to 150psi was probably a dumb ass move, a bit of an experiment if you like.

I'm running 23mm Vittoria Corsa Speed G+ tubs on Zipp 900 disc and 808 front


you are aware of this thread and all that has been done by Josh and Tom, right?

https://forum.slowtwitch.com/...%2C%20graph#p5996904

I'll check it out.
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Re: Tyre pressure question [zedzded] [ In reply to ]
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I'm 155-158lbs. I run 90-95 on my 23c supersonics and 85 on the 25c go4000s.
140 is just crazy!
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Re: Tyre pressure question [trailerhouse] [ In reply to ]
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and here is the chart

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Re: Tyre pressure question [nickag] [ In reply to ]
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nickag wrote:
and here is the chart
This is the plot I was referring to in my earlier post.
Looking at the green line, it's obvious that the sensible place to aim for is the relatively flat region prior to the break point at 110psi and that since there's not much lost moving even 20-30psi left from the break point compared with increasing even 10psi, you're best to play safe and err on the low side. That's especially obvious considering you also benefit from improved comfort.
The exact figures will vary with quality of road, loading of the wheels, tyre & tube types and speed. But the order of magnitude and shape of the plot is hopefully pretty representative and the best data I'm aware of currently.
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