Tire Pressure

6 10 2009
Setting Tire Pressure

Setting Tire Pressure

Running tires at max pressure doesn’t make them faster.  It just makes them ride more harshly.  Bicycle Quarterly has run some comprehensive tests on various tires to validate this and in my own experience it has proven true as well. I find myself explaining this over and over again in various online forums since it goes against commonly held cycling dogma.  Happily Jan Heine at Bicycle Quarterly has posted an article summarizing how to determine the correct pressure for your tires.  Now I can just post a link to the article and save my fingers the typing.

The only thing I would add to Jan’s article is that I find there is no need to get super precise about this process and generally just eyeball the vertical drop.  As long as I get it in the ballpark I don’t notice a major impact either way.  Since I’m lazy I tend to go for slightly less then optimal vertical drop when inflating my tires.  I’m not going to mess with them until they have lost a lot of air so my tires will reach the optimal pressure sooner or later and when they get noticeably soft I’ll repeat the process.


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11 responses

6 10 2009
gareth

While I am convinced by the testing in this article, I wonder about the incidence of pinch punctures. Pumping up your tyres until they are rock hard minimises the incidence of this sort of puncture. The marginal increase in efficiency through lower pressures might not be worth it if it leads to more time stationary at the side of the road

6 10 2009
thelazyrando

I’ve never had a pinch flat on any bike other than a mtn bike and I run my tires at moderate pressure only bothering to inflate them again when they are noticeably soft. If you stick to the recommendations of the article you won’t get pinch flats as they vary pressure by weight which is exactly what is required to avoid pinch flats.

7 10 2009
Gareth Dent

The flip answer Vik would be to say that you should try cycling on British roads :-)

More seriously, with my road bike and relatively light bodyweight, the BQ table give a front 23mm tire pressure of 75 psi (compared to 110 when I have just pumped them up and about 90 when they next see the track pump). I don’t know what that feels like but might give it a go and post a few photos. My feeling is at that pressure I would be taking chances not just with the tyre if I hit a pot hole at 20 mph but also with the rim – which would rather more expensive to replace.

7 10 2009
thelazyrando

The thing is no table is going to give you an exact answer that will work everywhere. If you have some very specific road issues – tons of square edge potholes – than sure use more pressure. I’ve lived in several big Canadian cities and traveled to several more in the US. I’ve also bike toured in Mexico and this principal works in all these places.

Personally if you have lots of big potholes I wouldn’t use 23mm tires. I’d be running a 40mm Scorcher on a Tikit or at least a 30mm Grand Bois if it was a 700c wheel.

Pressure is one way to deal with holes and bumps – tire volume is the other.

7 10 2009
Gareth Dent

‘The thing is no table is going to give you an exact answer…’

Absolutely agree and this is why we as cyclists end up going with ‘what feels right’

A rock hard 23mm is less efficient than a slightly softer one, but might be as efficient as a larger profile tyre.

Safe riding, whatever you choose

7 10 2009
thelazyrando

What you’ll get with a 40mm Scorcher on a Tikit is fast and comfortable….that’s my holy grail at the moment.

7 10 2009
Bill Gribble

I am excited to try this on my LHT tomorrow… tho it seems pretty radical to take my 85 psi 37mm tires down to sub-50 psi as recommended!

Between this article and the current month’s Paris-Roubaix tire article that’s a pretty convincing case that the lower pressure will make my bike faster and more comfortable for the work I can put out …

7 10 2009
thelazyrando

Hey Bill have fun experimenting. I would just note that the chart in the article is a guide – try the recommended pressure, but don’t hesitate to go up or down a bit depending on how the bike rides.

8 10 2009
Enough is enough for tyre pressure where efficiency and comfort meet | McNeill

[...] thelazyrandonneur.com, tyre pressure and comfort. share and tell: [...]

13 10 2009
Koen De Jaeger

I really would like to have such a chart for 50 mm tires. I have a schwable supreme 50mm 28 inch : http://www.schwalbe.com/nl/nl/produkte/tour_city/produkt/?ID_Einsatzbereich=9&ID_Produktgruppe=36&ID_Produkt=131&ID_Artikel=71&info=1 . I still have no clue what optimal pressure it should have :(.

13 10 2009
Vik

Koen,

You don’t need a chart. For 50mm tires the optimal pressure is a vertical drop of about 8mm when you are on the bike with your gear. That’s easy to see and it doesn’t matter much if you aren’t on the exact right pressure as long as you are in the ballpark.

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