Re: Tyre Pressure Leaderboard

Postby swtchbckr on Fri 10/Apr/15 12:08am

And i's should weigh in... I's just about 45 years of age and am struggling against keeping the weight under 90 kilos. On a good day I am under 90, but beer, food, and good living keep pushing me over... So who the fuck knows... Not me! And I don't seem to care that much either
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Re: Tyre Pressure Leaderboard

Postby mbl77 on Fri 10/Apr/15 5:58am

65kgs here.

Running Specialized Butcher 2.3 front, Purgatory 2.3 back (29er), on LB 23mm internal rims. 21psi front, 23psi rear.

And on the 26er xc bike with Specialized Captain 2.2 front (17mm rim), Fast Trak 2.2 rear (19mm rim), its 24psi front, 27psi rear.
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Re: Tyre Pressure Leaderboard

Postby dwgknz on Fri 10/Apr/15 8:35am

swtchbckr wrote:And i's should weigh in... I's just about 45 years of age and am struggling against keeping the weight under 90 kilos. On a good day I am under 90, but beer, food, and good living keep pushing me over... So who the fuck knows... Not me! And I don't seem to care that much either


Too many beersies maing? Tyre pressures on your skinny bike?
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Re: Tyre Pressure Leaderboard

Postby cyclenutnz on Fri 10/Apr/15 9:22am

My MTB perspective doesn't count for much as I go downhill like a helium balloon (then up like a lead one). However, for road I generally recommend 5psi lower on the front to make sure the casing is not over stiff. Target weight dist for road ~45/55 (I was 44/56 last I checked) so 5psi not sufficient for equal deformation in normal riding but, as has been pointed out, there are critical moments when you don't want the front tyre misbehaving.

It would be interesting to repeat tyre temp tests that I've done on the road for MTB. Unless someone else rides with an infra-red thermometer and can share the info? Dirt may insulate more than large rocks (Waikato road surface) which would increase suppleness. What I've found with road tyres is that slow tyres heat up more (thanks to higher frictional losses in the casing) both in roller tests and on the road (I'd wondered if being outside might increase cooling on slow tyres). Temperature has a big effect on tyre speed, at some point I'd like to test with carbon rims increase tyre temp (as that would help carbon be faster than alloy).

Unfortunately I've not had both the time and a windless day to test optimal pressure balance for rolling resistance (need a wind less day so that aero effects don't outweigh small tyre effects). In general would expect stiffer tyres to have a lower critical pressure (the point at which rolling resistance starts to increase with pressure). Which may be relevant to MTB if you're looking at a tyre that is heavily treaded with a lot of sidewall protection.

I realise that few MTBers care much for rolling resistance compared to traction so I'm just offering a perspective on how I go about road tyre/pressure selection.

For the record: MTB
Trek Superfly FS (Fox CTD)
Tyres with tubes, Bontrager 2.3 for summer, Conti Mountain King (2.4 I think) when it's wet
30F, 35R
Currently 103kg (well up on normal as no time for riding) which is making things squish more.
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Re: Tyre Pressure Leaderboard

Postby mfw on Fri 10/Apr/15 9:54am

More riders coming out the woodwork to show and tell.
I could do a 2016 version in 12 months and we can all see how we've done with the dieting :paranoid:

Code: Select all
                     PSI    PSI  TUBE/
NAME       TONNAGE  FRONT   REAR  T/L  INNER RIM/TYRE WIDTH, Other info
swtchbckr     90       4      4   ?    75mm   4.25 Charge Cooker Maxi 2 (Wowee, that's extreme)
mfw           76      18     18   TL   32mm   2.4  (must ride like a softie)
swtchbckr     90      20     20   Tube 29/30  2.4  5 Spot, doesn't care about weight anymore
Velocip'trian 70      20     23   Tube 25mm   2.4  Pinch flats ~every six months
mbl77         65      21     23   ?    23mm   2.3
Matahina       ?      22     23   ?    ?      2.35
mfw           76      23     23   TL   19mm   2.4  Glad to ditch these skinny rims
wachtourak    73      23     26   TL   23mm   2.35
mbl77         65      24     27   ?    17/19  2.2
Percy Pig     99      25     30   ?    24.5mm 2.3  Trail and DH, dents rims
shmoodiver   120      26     30   TL   23mm   2.35 (fast downhill)
Wobbler      110      32     32   TL   25.5mm 2.5
el_booto     200      30     35   TL   23mm   2.4/2.25 Smooth style with gnar streaming tendancies
cyclenutnz   103      30     35   Tube  ?     2.3 or 2.4
AgrAde        75      32     35   TL   23mm   2.3  Don't like burps
dwgknz        75      35     35   TL   19mm   2.25
AgrAde        85      ?      40   TL   23mm   2.3
el_booto     200      40     40   Tube 24.5mm 2.5 Smooth style with gnar streaming tendancies
Farm         100      45     45   Tube ?      2.35 Burps and bashes regularly
BikeKiller   130      50     50   Tube ?      2.35
Last edited by mfw on Fri 10/Apr/15 3:33pm, edited 2 times in total.
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Re: Tyre Pressure Leaderboard

Postby shmoodiver on Fri 10/Apr/15 2:29pm

I'd just like to add....

THERE IS NO F#*KING C IN SHMOODIVER!
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Re: Tyre Pressure Leaderboard

Postby Wobbler on Fri 10/Apr/15 2:29pm

:lol:
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Re: Tyre Pressure Leaderboard

Postby Velocipedestrian on Fri 10/Apr/15 2:51pm

Shmoo is not down with your f#*king C.

:D
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Re: Tyre Pressure Leaderboard

Postby Wobbler on Fri 10/Apr/15 2:53pm

Velocipedestrian wrote:Schmoo is not down with your f#*king C.

:D


fixed
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Re: Tyre Pressure Leaderboard

Postby Velocipedestrian on Fri 10/Apr/15 5:00pm

Ta, much betterer.
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