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Tyre pressures on a

Ian Cairns2022-04-29 08:23:35

Hello,

I have a new Gepida Thoris Tandem (the last available one in the country that I could find) and would like to know what tyre pressures you would recomend.

The tyres are Schwalbe Energizer 700 X 47c reflective. The "teams" weight is about 25 stone. We intend to use the tandem for fire tracks through woods as well as road and canal use.

 

Thank you for your help.

 

Regards

Ian Cairns

Keith Hales2022-04-29 08:31:39

All tyres have their pressure range specified on the sidewall. I should think the max pressure on the rear, and 10-20% less on the front, see how that goes.

Keith Hales

Lawrence McPhillips2022-04-29 10:44:38

You'll find as many (or more) opinions on the 'correct' tyre pressure as there are tyres on the market!  IMHO there is no right answer, you need to see what works best for you.  I take the view that Berto's 15% deflection rule is a great starting point:

https://forum.cyclinguk.org/viewtopic.php?t=122289&start=45

https://www.renehersecycles.com/tire-pressure-take-home/

https://www.renehersecycles.com/minimum-tire-pressure/

Our Orbit tandem has a rear hub motor and now weighs about 35Kg with accessories fitted.  The all up weight is about 165Kg with riders aboard.  We use the E-bike specific version of Schwalbe Marathon Plus tyres (622 x 40) which have quite firm sidewalls.  We have a decent balance of grip / comfort running these at 65psi rear, 60psi front.  I use the same tyre on a solo E-bike at 50psi rear, 45psi front (I'm about 65Kg).

I don't agree with everything Andy Blance at Thorn cycles says, but I do agree with him that most cyclists run their tyre pressures far too high.

When running the MP's on our tandem at their maximum pressures, the ride was incredibly harsh.

David Catlow2022-04-29 17:43:05
It's worth bearing in mind that your rim has a maximum pressure too- my DTSwiss rims are rated as 4 bar max, but the Schwalbe Marathon Mondial DD 700x40 tyres are 3.5 to 6 bar. When our tandem was new, I pumped my rear tyre to around 5 or 6 bar believing that to be OK and it later blew clean off the rim, fortunately at relatively low speed! Lesson learnt and it's now always less than 4 bar in them, which is actually plenty hard enough anyway.
Edward James Neame2022-05-01 16:21:56
After years of using all sorts of rules for tyre pressures for allsorts of tyres I've found the Silca calculator https://silca.cc/pages/sppc-form gives the best results so far.  I've used it for our tandem (44mm nom tyres) wife's electric (42mm nom tyres), my cross bike (53mm nom tyres) and my road bike (25mm nom tyres).  Pay attention to the guidance notes as it is based on actual tyre width and road surface.
Ian Cairns2022-05-03 10:54:45

Hello,

Thank you for the info.

We went with 60PSI at the back and 55PSI front. Checked with a digital pressure gauge that was about 5 PSI different (lower) to my bike hut track pump gauge.

Bike did really well , even went up a gravel climb that I walk up on my own bike, just a slight back wheel slip at one point. The tyres state 45 to 70PSI range so as long as we don't get any pinch punctures, I am happy with between 55 and 60PSI for a comfortable ride.  The air fork and stoker Thudbuster also help! 

We had a lot of interest from people about the Tandem, its certainly a talking point!

 

Ian