azza_333

Touring Tyre Pressure

I have got a tour in Japan in 6 weeks’ time, all 99% sealed roads, but I still haven’t decided on what tyre pressure would be best. The tyres I will be using are Schwalbe Marathon Supreme HS 469, HD Speed Guard (Non-Tubless version) 700x35c. Below I have listed my weights.

Bike: 15kg (33lbs)
Rider: 75kg (165lbs)
Luggage (loaded on rear rack only): 15kg (33lbs)
TOTAL: 105kg (231lbs)

Normally I would just run max pressure (85psi) for least rolling resistance, but I have read a few articles that say max pressure may not always be the fastest (rough roads). In the cycling about article it recommends not exceeding 75psi front and 80spi rear. Giving me a range on my tyre of 60-80psi. What Tyre Pressure Should You Use for Bicycle Touring? - CyclingAbout

Would 80 psi be the fastest? given 99% of my route will be sealed roads.
Would I risk any pinch flats at 60psi?

mstateglfr 

Your total weight is my body weight. i run 35s at 85ish with just me riding(no gear).
I doubt 75 for you would be bad.

I get the wider tire and lower pressure trend we are in right now and accept the premise behind the trend, but i also think that it can get a bit absurd. 60psi probably wont flat, but would it start to be a wiggly drag?

I would load up with those weights and try a few miles at each psi. No need for a 60mi ride or anything. 3mi and you will know if a psi feels too sluggish.

tyrion

I'd go with the lowest pressure that doesn't feel mushy/wriggly in hard cornering with the bike loaded. For me comfort and safety are more important than a fairly small increase in efficiency.

I've put a lot of miles on those exact tires and never had a pinch flat. My bike and I weigh more than 231 lbs.

boomhauer

Lower pressure works good for long stretches of road construction. 70 psi?
I've released air when I needed to; knowing the next 8 miles were road construction (gravel). PUmp them up later.

bradtx

azza 333, You could try 80 PSI in the rear and 70 PSI in the front to start. This is, IIRC, about what my tire pressures were with a 40 lb. rear only load.

Brad

djb

In all serious, you can take the recommendations here from similarly weighing folks, but the best thing is to take some time with your bike with the load you'll be using, and trying diff pressures on diff types of paved surfaces and feel the differences yourself.
For ages I never really thought of my tire pressures, would put them to mostly the max pressure and thought it was best. Commuting along the same route and on diff bikes made me become more aware of how diff tire widths and pressures felt along my paved regular route that has a huge range of surface quality, from great to terrible rough bits.

the one thing that has become clear to me over the last bunch of years is that the views that you stated about highest pressure not being the fastest, to me this is absolutely true. A super hard tire may "feel" faster, but the reality is that the diff with lower pressures (to a certain point of course) is not really noticeable on good pavement (pretty much same speeds) but extremely noticeable in a good way over bumpy pavement--you dont get beat up as much, which is a win for your body, and you can hear and feel that less force/jolts are going into your frame/spokes/rims/panniers.

bottom line, get out there with a good pressure gauge and try diff pressures, if you are the slightest bit attentive, you will notice the differences. Just dont get caught up in the whole thinking and feeling that a hard, jarring tire feel is faster.
You will notice though that often a few or 5psi will make all the difference in how a tire rides comfort wise. On my recent trip, going from 50psi to 45 on the rear, and from 45front to 40 or 42 made a real diff in riding comfort.

I was using supremes also, but 26x2, so much lower pressures, but I was still impressed by how the tires rolled in general--and as they are fairly supple tires, take advantage of lower pressures (opposed to max pressures) so that you can take advantage of thier nice feel and ride due to the supple sidewalls.
**Because the sidewalls are so thin, you do have to be careful about not riding up against a sharp rock or whatever, but using common sense is fine.

gerryl

My tires are rated max 85 psi, I usually never go to max pressure, it's just too harsh. One thing that pro racers have noticed with wider tires, is less fatigue due to the body having to absord less road shock, something to take into account for long rides.

Tourist in MSN

I think that the 15 percent tire drop described at this link is a good starting point for rear tires:
https://janheine.wordpress.com/2016/...ure-take-home/

I could not find the original article on line anymore, perhaps it disappeared? But I found the above link instead.

That calculation method results in an absurdly low front tire pressure, instead I usually just use about one bar less pressure in front than rear. If you weight is higher than the highest value on the graph, I have had good luck printing it off, using a straight edge and drawing the lines further to the right.

My goal is not speed, it is a mix of pedaling efficiency and comfort. If I want to go fast, I run higher pressures, but I am rarely in that much of a hurry. I use stiffer tires with some flat proteciton, not the really supple tires. But I do not have a carbon bike with electronic shifting like you do, so you might want higher pressures for your race/tour.

djb

I always found his chart to have too low front pressures also, but again, see how x and y and z pressures feel to you, over bumpy stuff and around corners.

My suggestion is to start higher and then take 5psi out at a time, you'll quickly get a feel for things.

Am I the only one who finds bar numbers overly , not sure the expression, but 4 bar is 58 psi and 3 is 43-44. Big big difference.
I guess you just have to get used to .1 or. 2 bar differences, and I'm clearly used to reading psi marked pumps and gauges.
Seems it is easier to make large pressure errors for someone not paying attention to the decimals.

Anyway, like all things in life, it's the details that makes the differences.

Timequake

How about you try riding your bike with different tire pressures and figure out which one feels best for you? So much hand holding needed on these forums, it's a wonder any of you ever make it outside to ride.

Tourist in MSN

One bar is very close to one atmosphere of pressure. So yeah, one bar is a lot. I am not sure if the term bar came from barometric pressure, but mentally I think of it that way. That makes it easy to remember.

At least we are not talking about kg/cm^2 anymore, I never could figure out what to do with that, I had to tape a conversion table on my pump to figure out what each tire needed.

djb

I freely admit to not really paying attention or even looking at bar settings on my pumps and gauges, so I realize I'm just being psi centric, and 4.1 or 4.3 would be no different than x psi differences.
I switch between kph and mph easily, but never take the time to remember bar readings for my bikes, household bikes range from 2.5 inch to 25mm tires.

djb

You certainly have a point there.

pdlamb

Commuting around OP's weight, I'll normally pump tires up to 90 psi (used to go to 100, but I don't need that). Ride until they feel a bit soft, which is about 70 psi on my thumb, and pump it back up. I could go as low as 75 with good comfort and adequate speed, but I don't pump every day (just every 2nd or 3rd day). 70 psi is a drag, it's a good way to get extra exercise without extra speed IME.

djb

just looked at this article, and while its a bit of a reference perhaps, its just plain goofy that he doesnt say what he weighs, and or mentions if his "experimenting" to get to his recommendations on his chart are only with him (at an unknown body weight) or with some gear also (unknown weight)

I suspect that its him only, but again, the fact that he doesnt put his weight unfortunately shows that despite the good intentions, its not really a serious article in terms of giving a proper indication for folks like you wondering about pressures.

It is interesting that his max recommendation for 26x2 inch tires of 45f and 50r is just a bit higher than what I used on my trip, albeit with me at 135 and 50lbs of stuff.

niknak

The number, like saddle preference, is unique to each rider. I run enough pressure to prevent pinch flats and wallowing in corners. More than that provides no perceivable benefit.

Trevtassie

I'd be fitting as big as tires as I could for Japan, you'll probably find yourself riding on the footpath/sidewalk more than you would normally expect. Because the truck and car drivers are so nice to you, you end up trying to be as nice as you can back and make things as easy as you can on them, especially on narrow roads. There are sidewalks in places you wouldn't expect, way out in the country. The sidewalks have a very big curb and big dips at driveways, plus there are some hard core grasses that mess with them a bit.

manapua_man

Why not just adjust tire pressure to suit conditions while under way? I never really got why people fixate so much on a specific pressure ahead of time rather than actually riding their bike and getting a feel for what is more/less ideal for different terrain.


The cops will yell at you to get on the sidewalk in places. IMHO having narrow tires isn't that big a deal though, my road bike with 23mm tires does just fine. It's a little squirrelly when there's sand/gravel but nothing that would make me freak out, even on those mountain roads that clearly haven't been maintained in years.

azza_333

The guy who wrote the article weighs 78kg pretty much the same as me, he had his weight listed in the "How much does weight slow you down article"

djb

Thanks, so about 171lbs, about 35 more than me.
With gear or just him?
Anyway, get a good gauge and try stuff out, is worth it

Trevtassie

Dunno, 4000km and 10 weeks in Japan and I've never been yelled at by a cop. I have been waved too a lot by them however. Probably because I worked out that sharing narrow roads with large trucks that have to give way to you would cause havoc. 99.9% won't push past you, so you can cause them some serious inconvenience. So I ride the footpath sometimes, but in order to be able to do that at a reasonable speed with a good load you need some big tires. There are some big lips on crossing. As my partner said, "some of this footpath riding is improving my MTB skills". You could do it with small tires but you'd be paranoid about pinch flats.

But then if you are riding the Shimano Kaido or somewhere like that, it'd be fine to use 35mm tires.

manapua_man

Lived there for a while and I might move back - also still go there 3-4 times a year and bring a bike over when I do. I've seen cops yell at people for riding on busier roads in metro areas on more than a few occasions. A lot of the time they won't bother with foreign looking people because of the (potential) language barrier, but if it's bad enough they'll actually chase you down.

Narrow tires work fine. I beat the crap out of my road bikes and folding MTB going all over the place every weekend, and would take the train back from wherever I ended up when it was time to get home and go back to work. The one thing I really worried about are the narrow/deep uncovered gutters along some of the roads. It'd be nasty if you weren't paying attention at night and landed in one of em.

GAJett

For calculating (estimating) tire pressures I like the Beto Tire Pressure app that is based on work by Frank Berto and the basis for much of Jan Heine's initial work. It's available for both Apple and Android.

The OP doesn't state what type of bicycle he will be using, so I'm assuming a standard road bike with down-turned handlebars. Following that, entering the various weights given, the app returns 71 psi rear, 38 psi front. Many above have suggested that such a low front pressure would be absurd. Whatever. Just begin by treating these starting points and experiment from there.

I follow these recommendations for my own bike running 54-ish rear and 42-ish front (I typically just round to the nearest 5 psi and have no estimate for the accuracy of my gauge). Note that my weights and weight distributions differ (significantly) from the OP's. I may even DROP my pressures from there, as an experiment.

One reported advantage to riding lower pressures, that wasn't mentioned above, is a reduced likelihood of flats.
Cheers!
And have a great trip. (And don't obsess too much about this -- at least go high enough to avoid pinch flats.)

GamblerGORD53

I would go 70 F, 75 R. Hard tires are hard on the bearings.
Max pressure is not supposed to be the used pressure.

DropBarFan

For your setup I'd bet you could go down to 55 front/60 rear psi w/o problems. Higher pressure is a little faster but less comfy & perhaps less safe on bumpy descents.