Author Topic: Rene Herse tire pressure calculator  (Read 741 times)

Danneaux

  • Administrator
  • Hero Member
  • *****
  • Posts: 8048
  • reisen statt rasen
Rene Herse tire pressure calculator
« on: March 25, 2022, 06:12:47 PM »
Hi All!

For the last 25+ years, I've used the 15% "drop" tire pressure recommendations developed by American petroleum engineer and Bicycling magazine technical editor Frank Berto in concert with some leading tire makers' data. I've found this worked well for my needs and in the last several years, an Android app was developed from his body of work that makes pressure calculations quick and easy based on bike and rider weight and rider positioning, providing differential F/R pressures. For a bit more on this, see one of my past posts...
http://thorncyclesforum.co.uk/index.php?topic=12834.msg96188#msg96188

Now, Rene Herse Cycles has developed a free online tire pressure calculator based on their own research as developers of the original Compass brand (now also Rene Herse) tires. See...
https://www.renehersecycles.com/tire-pressure-calculator/

It comes with two intriguing caveats...
Quote
The calculator gives you two tire pressure recommendations. Use the ‘Soft’ value for rides on rough roads or if you prefer a more comfortable ride. Use the ‘Firm’ value if you like your bike to have a firm feel. The ‘Firm’ values also provide a considerable margin of safety if your pressure drops a bit. With the ‘Soft’ pressure, you are stressing your tire casing more, and it may wear out faster.

Bicycle Quarterly’s extensive tire tests have shown that – on smooth roads – supple high-performance tires roll at the same speed at either of these two pressures. Pressures between these two values roll a little slower. On rough surfaces, your bike will be faster at the ‘Soft’ pressure.
And, at variance with the Berto method...
Quote
Front v. Rear Pressure
Most bikes carry more weight on the rear wheel than the front. However, when you brake hard, almost the entire weight shifts to the front wheel. For that reason, it’s not advisable to run a lower pressure in the front tire.
I recently got a pair of free (Craigslist/Gumtree curbside giveaway) nearly new handmade Challenge Strada Bianca Pro 700x36 tires. See...
https://road.cc/content/review/challenge-strada-bianca-pro-tlr-280335
Both are dirty, front one perfect, rear with a 5mm cut in the sidewall I plan to glue and boot with Tyvek before trying on my gravel bike using the Herse pressure recommendations. It'll be a fun experiment to see if I like the tires and to also play with pressures while enjoying some of my favorite gravel roads.

I'm not at all sure the Herse calculator recommendations will work so well/produce similar rollout results if applied to tires with sidewalls stiffer than their own brand. That's why I'm planning to try them with the Challenge Strada Bianca Pros, the closest tires I have to those produced by Herse. If one of you try the Herse calculator and recommendations, I'd love to hear your impressions and results for the tires used.

Best,

Dan.

Matt2matt2002

  • Hero Member
  • *****
  • Posts: 1692
Re: Rene Herse tire pressure calculator
« Reply #1 on: March 25, 2022, 09:55:03 PM »
Interesting article.
Thanks Dan.

Schwalbe Marathon Plus HS440 Tyre with Reflex - 26 x 1 3/8 Inch / 650 x 35A 37-590
ETRO37-590

Am I right in thinking the tire width is 37mm?

Best

Matt
Never drink and drive. You may hit a bump  and spill your drink

mickeg

  • Hero Member
  • *****
  • Posts: 2287
Re: Rene Herse tire pressure calculator
« Reply #2 on: March 25, 2022, 10:43:37 PM »
I am not going to try to figure this out, is one slightly above and one slightly below the 15 percent?

When they first came out with the 15 percent, I thought that was absurdly too low for front, they did not clarify that initially that the front should have more than the 15 percent for braking reasons.  I think it was originally published in Bike Quarterly, I have a one page version with no date.  The ACA version has a date of 2009, I think this came out later.
https://www.adventurecycling.org/default/assets/resources/200903_PSIRX_Heine.pdf

Because I thought it too low, I generally run my front at about 70 to 75 percent of the rear pressure (if rear is at 80 psi, I would run front at about 60 psi).  I have no basis for this ratio that I have been using, but have been doing it for years and it has worked well.  But I have run my front lower than that on rough chip seal when the front gave me too much vibration on the rough pavement.

Right now on my Lynskey with 37mm tires, I have an old Marathon XR on the front, I run that a bit higher than my 70 or 75 percent of rear norm because that is a high rolling resistance tire and at lower pressures it feels like I am pulling a boat anchor.

For touring, I think I usually have my rear about 15 percent tire drop, but with a heavy load that 15 percent might be the tire max pressure or close to it.

Years ago, I basically took their chart and ran the lines farther to the right with a straight edge because with my touring load on the rear tire, I was off their chart.  My 700c touring was on 37mm tires.  I also used the 37mm pressure for my 40mm Marathon (with Green Guard) tires on my 26 inch wheel Sherpa.

I will probably never run tubeless, but I have heard that road (narrow) tires that are tubeless at low pressure can "burp" in corners and suddenly lose enough pressure to cause crash and injury.  I have no clue if these pressures they are talking are low enough to be a hazard for tubeless or not, just commenting on that. If there is a minimum tire pressure listed for a tubeless tire, I would NOT go below that.


Interesting article.
Thanks Dan.

Schwalbe Marathon Plus HS440 Tyre with Reflex - 26 x 1 3/8 Inch / 650 x 35A 37-590
ETRO37-590

Am I right in thinking the tire width is 37mm?

Best

Matt

I would say that is close enough.  Or see what they say in the link I posted above.

Danneaux

  • Administrator
  • Hero Member
  • *****
  • Posts: 8048
  • reisen statt rasen
Re: Rene Herse tire pressure calculator
« Reply #3 on: March 25, 2022, 11:30:54 PM »
Quote
Schwalbe Marathon Plus HS440 Tyre with Reflex - 26 x 1 3/8 Inch / 650 x 35A 37-590
ETRO37-590

Am I right in thinking the tire width is 37mm?
Most likely or within 2mm or so...but I always caliper mine to make sure, as actual tire width depends in part on the width of the rim.

Matt, you may wish to double-check the tire size if you intend this for your Raven, as it is a fractional 26in, not a decimal 26in. The diameter is very different, as 26in is intended for rims labeled 559mm, while this one is larger at 590/650A. For more information on the difference, see...
https://www.sheldonbrown.com/tire-sizing.html#fraction

Best,

Dan.

Moronic

  • Full Member
  • ***
  • Posts: 152
Re: Rene Herse tire pressure calculator
« Reply #4 on: March 26, 2022, 01:14:48 AM »
The calculatormrecommends 33psi as the 'soft' pressure for my 50mm tyres at my weight.

That's about what I've found good from trial and error. Although I am starting to think mine work better around the 28-30 mark.

That's G-One Speeds, recommended minimum 35 I think. There was a piece on a good Euro bikepacking site that argued most makers' recommended minimums were way too high for best results.

martinf

  • Hero Member
  • *****
  • Posts: 992
Re: Rene Herse tire pressure calculator
« Reply #5 on: March 26, 2022, 07:37:20 AM »
I compared the results of the calculator for the four tyre sizes I use on full size bikes with the pressures I currently use.

My current pressure for the rear tyre is within the range of the calcultor, near the "soft pressure for my "wide" tyres but near the "firm" pressure for the narrower tyres I use on the two "lightweight" bikes. 

I run the front tyre with a lower pressure than the rear, it has worked for 40+ plus years so I will carry on doing this.

JohnR

  • Sr. Member
  • ****
  • Posts: 473
Re: Rene Herse tire pressure calculator
« Reply #6 on: March 26, 2022, 09:32:52 AM »
I found that having front a bit below 30 psi and rear a bit above 30 psi worked well with my Mercury's 50mm tyres and is consistent with the soft end of the calculator's range although I wouldn't describe those pressures to be "soft" (nearer 20 psi).

B cereus

  • Jr. Member
  • **
  • Posts: 64
Re: Rene Herse tire pressure calculator
« Reply #7 on: March 26, 2022, 11:49:29 AM »
An interesting read Dan. Rene Herse have always been a bit evangelical in their pronouncements. A lot of what they preach is good common sense advice but some is marketing led and needs to be evaluated in the light of ones own particular circumstances.


I've been using Berto's recommendations for a number of years now but have never regarded them as set in stone. They are however a useful reference from which I make my own adjustments according to circumstances. I don't really buy into the idea of equal pressures front and rear. It seems to me that I spend very little time braking when compared to the overall time spent riding. As far as I know I've never suffered an issue under braking that could be attributed to too low a front tyre pressure but I certainly detect an increased  road buzz  when the pressure is too high.

UKTony

  • Full Member
  • ***
  • Posts: 101
Re: Rene Herse tire pressure calculator
« Reply #8 on: March 26, 2022, 12:17:18 PM »
I found that having front a bit below 30 psi and rear a bit above 30 psi worked well with my Mercury's 50mm tyres and is consistent with the soft end of the calculator's range although I wouldn't describe those pressures to be "soft" (nearer 20 psi).

30psi for 2” tyres seems low to me unless it’s for particular surface conditions. Not long after I bought my Mk 2 Nomad I had a very scary experience on 26”x2” Schwalbe Duremes at speed on a narrow lane round a sharp bend at the bottom of a hill when the front tyre started to wobble. I rang Thorns and spoke to Andy Blance as a result of which I started using his recommended tyre pressures on page 40 of the Mega Brochure, for the Duremes and subsequently for the Marathon Supremes which I’ve been using all year round now for a few years, here

http://www.sjscycles.com/thornpdf/thorn_mega_brochure.pdf


Matt2matt2002

  • Hero Member
  • *****
  • Posts: 1692
Re: Rene Herse tire pressure calculator
« Reply #9 on: March 26, 2022, 05:37:36 PM »
Quote
Schwalbe Marathon Plus HS440 Tyre with Reflex - 26 x 1 3/8 Inch / 650 x 35A 37-590
ETRO37-590

Am I right in thinking the tire width is 37mm?
Most likely or within 2mm or so...but I always caliper mine to make sure, as actual tire width depends in part on the width of the rim.

Matt, you may wish to double-check the tire size if you intend this for your Raven, as it is a fractional 26in, not a decimal 26in. The diameter is very different, as 26in is intended for rims labeled 559mm, while this one is larger at 590/650A. For more information on the difference, see...
https://www.sheldonbrown.com/tire-sizing.html#fraction

Best,

Dan.

Thanks again.

I wondered if the 'ETRO 37-590' was a reference to the tire width? As in 37mm wide..

Just weighed myself and Raven resulting in 95Kg total.
So at 37mm gives me a soft 43 & firm 53.

Slightly higher than my usual pressure.

As noted: good guidelines for personal preferences.

Best

Matt
Never drink and drive. You may hit a bump  and spill your drink

JohnR

  • Sr. Member
  • ****
  • Posts: 473
Re: Rene Herse tire pressure calculator
« Reply #10 on: March 26, 2022, 06:02:00 PM »
30psi for 2” tyres seems low to me unless it’s for particular surface conditions.
I should add that's for my normal lightly-loaded condition with me, the bike and a small bag being no more than 85kg. Some sections of my local roads include some badly patched potholes.

Andre Jute

  • Hero Member
  • *****
  • Posts: 3847
Re: Rene Herse tire pressure calculator
« Reply #11 on: March 26, 2022, 06:33:53 PM »
http://www.sjscycles.com/thornpdf/thorn_mega_brochure.pdf

Thanks for the link. Tony. It turns out I already had an up-to-date copy in my Bike Bible. But I spent a most enjoyable hour reading here and there.

30psi for 2” tyres seems low to me unless it’s for particular surface conditions.

Two bar, which is about 29psi if I remember correctly, seems good to me on 622x60mm Big Apples. I've been lower but not recently since I'm heavier and the roads are worse, so I'm adapting, as you did.

I would add though, about your scary moment, that in the longer term it is worth considering going to wider bead-to-bead rims if available. Tyres seat more securely in rims wider across the beads than 40 percent of nominal tyre width, and under 40 percent bead width definitely calls for higher inflation to keep the tyres attached and working.

Andre Jute

  • Hero Member
  • *****
  • Posts: 3847
Re: Rene Herse tire pressure calculator
« Reply #12 on: March 26, 2022, 06:40:56 PM »
I run the front tyre with a lower pressure than the rear, it has worked for 40+ plus years so I will carry on doing this.

I've been cycling only 80 percent as long you, Martin. But I reckon that is long enough to conclude that unnecessary experiments with the dynamic friction joint between the tyre and the road could itself easily be the cause of an unwanted incident.

PH

  • Hero Member
  • *****
  • Posts: 1750
Re: Rene Herse tire pressure calculator
« Reply #13 on: March 27, 2022, 01:33:54 PM »
Thanks for the link Dan, that made interesting reading, though my thoughts and methods remain as per the previous thread you've referenced - That is I start with the 15% drop and experiment till I find what I like, which doesn't seem to stray far from it. I also have a preference for a narrower tyre on the front, I'm not recommending or justifying, it's something I've done for years and works for me.  It also has the advantage that it evens the pressure so I only have one number (Per bike) to remember and also wear goes some way to matching the wear.
As the first paragraph in that article says, there's so many factors and preferences - IMO so many it's impossible to separate them.  A quick comparison to the calculator shows that all mine are roughly within the range, though it's noticeable that the narrower the tyre the firmer I like it - which brings me back to previous point, because it's also the fact that the narrower the tyre the more likely I am to be using it on better surfaces.
Then there's the difference between optimal and acceptable, both how far from the optimal you can wander and how much difference it makes.  None of my roadside pumps have a gauge, I've ridden countless miles with sub optimal pressures and it's been fine. sometimes noticeable, sometimes not, never enough to bother doing anything about it till I'm home. 

When I rode an E2E, averaging 100 miles a day for 11 days, I took a Schwalbe gauge and checked the pressures each morning, my companion checked his the week before we set off and not again - Who was right? Who cares  ;)

I'm not sure about this:
Quote
Front v. Rear Pressure
Most bikes carry more weight on the rear wheel than the front. However, when you brake hard, almost the entire weight shifts to the front wheel. For that reason, it’s not advisable to run a lower pressure in the front tire.
Assuming you're braking in a straight line and the pressure is enough to keep the rim away from the road, what's the problem with the front tyre compressing under braking?  I'd have thought the extra contact patch would be an advantage.

mickeg

  • Hero Member
  • *****
  • Posts: 2287
Re: Rene Herse tire pressure calculator
« Reply #14 on: March 27, 2022, 01:57:19 PM »
... Not long after I bought my Mk 2 Nomad I had a very scary experience on 26”x2” Schwalbe Duremes at speed on a narrow lane round a sharp bend at the bottom of a hill when the front tyre started to wobble. I rang Thorns and spoke to Andy Blance as a result of which I started using his recommended tyre pressures on page 40 of the Mega Brochure, for the Duremes and subsequently for the Marathon Supremes which I’ve been using all year round now for a few years, here

http://www.sjscycles.com/thornpdf/thorn_mega_brochure.pdf

Thanks for posting.  I had forgotten that Thorn published recommended pressures.  I knew they had max pressures based on rim strength but I had forgotten that they had recommendations.

I almost always run 57mm tires on my Nomad Mk II, Andra 30 rims.  I had some screwy handling on a curve at speed several years ago from too little pressure in a on a too narrow rim for that tire width.  Since then I have quit trying lower pressures that I wanted for better grip on that too narrow rim.  But on several previous threads I ranted about my disagreement with Thorn on tire and rim widths so I won't elaborate here.

Since then for around home use on an unladen bike I run 35 psi Front and 45 psi Rear.  For that tire width, they recommend 35 Front and 40 Rear which is same as I have been using for the front, I have been 5 psi higher in the rear.  I will keep using the pressures I have been using for unladen riding.

Touring with a heavy load, I do not have a firm list of numbers that I follow, but I think that I probably used about 45 Front and 55 Rear on that bike with 57mm.

Touring on that bike I have been using Marathon Extremes (discontinued) at 57mm and folding bead.  For around home use have been using a Hutchinson Cobra 57mm mountain bike tread.  Both tires have a pretty supple sidewall and roll surprisingly well on pavement.

I have a piece of paper taped to my floor pump that lists the pressures for unladen riding around home for my bikes.  I am not going out to the garage to get the pump to cite them, but it lists my common tire sizes and the F and R pressures:
28mm
32mm
35/37mm
I do not recall if I listed 40mm, that bike is in storage.
50mm
57mm