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Compressor for bike tyres

philsallissphilsalliss Posts: 175
edited November 2013 in Road general
Just bought a air compressor from local tool shop on offer with kit for inflating tyres. Now just read a few things that seem to suggest you can't use it for inflating bike tyres. Can anyone clarify whether compressor is fine for road bike tyres?

Posts

  • 964cup964cup Posts: 1,361
    Bang!

    Not a good idea. Any compressor with enough oomph to inflate car tyres will have way too much for a bike.
  • http://www.screwfix.com/p/stanley-82160 ... _container

    Oh well should have done research first was bought on a whim. It does have a pressure inflater gun attachment bit
  • diamonddogdiamonddog Posts: 3,420
    That's just plain lazy :)
  • It's fine if you're careful, I often use mine.
  • diamonddog wrote:
    That's just plain lazy :)
    Probably but I don't have a manual pump and have several motorbikes and two road bikes and always checking tyres so with the compressor being on sale kind of made sense to get run as would be quicker for motrovike tyres and pedal cycles tyres
  • 964Cup wrote:
    Bang!

    Not a good idea. Any compressor with enough oomph to inflate car tyres will have way too much for a bike.


    Not sure about that - car tyre 32psi, bike tyre 100psi.....
  • bigpiklebigpikle Posts: 1,690
    its the volume of air it shifts - how much air is going in to get a huge car tyre to 32psi and whats going to happen to a tiny bike tube with all that air going in very rapidly....
    Your Past is Not Your Potential...
  • ddraverddraver Posts: 23,203
    It ll be useful if you ever go tubeless...
    We're in danger of confusing passion with incompetence
    - @ddraver
  • There seems to be a little misunderstanding here. There are two main measures for a compressor - pressure and delivery.

    No matter what the displacement, if a compressor can only deliver 40 psi for example, it isn't going to over inflate a roadie tyre. That particular compressor is listed at 116 psi. OK for road tyres. Uncontrolled, may be a problem for children's bikes or MTB. It doesn't matter the delivery rate, a 116 psi compressor won't over inflate a 120 psi rated tyre, no matter how much it can deliver.

    The problem comes when used carelessly with a low volume, low pressure tyre - Think children's bikes. Low volume means a small amount of extra air bumps the pressure up a lot.

    Used sensibly, a compressor like that is OK on any tyre, but it is a whole lot easier with a regulator like http://www.screwfix.com/p/air-filter-re ... tid=266018. Set the regulator at 30 psi and you won't over inflate a 30 psi tyre.
    Giant Defy 2
    Large bloke getting smaller :-)
  • cattytown wrote:
    There seems to be a little misunderstanding here. There are two main measures for a compressor - pressure and delivery.

    No matter what the displacement, if a compressor can only deliver 40 psi for example, it isn't going to over inflate a roadie tyre. That particular compressor is listed at 116 psi. OK for road tyres. Uncontrolled, may be a problem for children's bikes or MTB. It doesn't matter the delivery rate, a 116 psi compressor won't over inflate a 120 psi rated tyre, no matter how much it can deliver.

    The problem comes when used carelessly with a low volume, low pressure tyre - Think children's bikes. Low volume means a small amount of extra air bumps the pressure up a lot.

    Used sensibly, a compressor like that is OK on any tyre, but it is a whole lot easier with a regulator like http://www.screwfix.com/p/air-filter-re ... tid=266018. Set the regulator at 30 psi and you won't over inflate a 30 psi tyre.

    Thanks mate. I think it's got something similar on it to lower the total psi anyway. Only just got it so not really fiddled it yet.
  • mfinmfin Posts: 6,724
    Slightly off topic, but Bosch used to make the Pag 12 rechargeable pump, you see mechanics in Grand Tours running up to bikes with them sometimes, but they aren't sold anymore I don't think.

    $T2eC16JHJIYE9qUcNbwUBR%29%28dSsU,g~~60_35.JPG

    http://www.youtube.com/watch?v=y8UZbhJzA4o
  • Some strange replies, why should a compressor be any different to a pump? It's just air for crying out loud. You have a manual control, pressure regulator and gauge, totally idiot proof!
  • cougiecougie Posts: 22,512
    Manchester Velodrome had an automatic air line so it can be done. I'm sure I've seen bike shops in Germany with something similar outside.

    Although I'd have thought a track pump was far less hassle ? Its only a few pumps.
  • There is that - I have a decent compressor in the garage, but normally reach for the track pump - it is quicker and quieter.

    Paul.
    Giant Defy 2
    Large bloke getting smaller :-)
  • 964cup964cup Posts: 1,361
    Hum. I think I take back what I said now I've done the maths.

    The volume of a car tyre is about 85x the volume of a road bike tyre (based on 700x23c vs 215/35R19). At 130psi (9 bar) a 23c tyre holds a bit over 2.4l of air; a car tyre at 40psi (2.7 bar) holds 85l. Car tyres are rigid, so hold 1 bar when empty; the 2.7 bar is actually 3.7 bar (gauges are zero-compensated for atmospheric pressure). Assuming you can fill a car tyre from empty in 30 seconds, that's a flow rate of about 2l per second (from 23l at 1 bar to 85l at 3.7 bar). So you'll fill a 23c tyre to 9 bar in about 1.2 secs. If your regulator works properly and is not zero-compensated, I suppose actually that would be fine - it's not really any faster than a CO2 cartridge.

    On the other hand, if you don't have a regulator and your compressor offers significantly more than 9 bar then I think it's less clever, given that every 8th of a second adds another bar of pressure.
  • Even that's not accurate - as you get higher pressures in the tyre, the pressure gradient will be shallower, so the later bars of pressure will be slower.

    I think the precis is: be sensible and you will be OK.
    Giant Defy 2
    Large bloke getting smaller :-)
  • 964Cup wrote:
    215/35R19

    That's a fairly blingy wheel/tyre. Have you been on 'Pimp my Ride'?
  • 964Cup wrote:
    Hum. I think I take back what I said now I've done the maths.

    The volume of a car tyre is about 85x the volume of a road bike tyre (based on 700x23c vs 215/35R19). At 130psi (9 bar) a 23c tyre holds a bit over 2.4l of air; a car tyre at 40psi (2.7 bar) holds 85l. Car tyres are rigid, so hold 1 bar when empty; the 2.7 bar is actually 3.7 bar (gauges are zero-compensated for atmospheric pressure). Assuming you can fill a car tyre from empty in 30 seconds, that's a flow rate of about 2l per second (from 23l at 1 bar to 85l at 3.7 bar). So you'll fill a 23c tyre to 9 bar in about 1.2 secs. If your regulator works properly and is not zero-compensated, I suppose actually that would be fine - it's not really any faster than a CO2 cartridge.

    My head hurts!
    Ribble Ultralite Racing 7005, Campagnolo Veloce groupset, Campagnolo Khamsin G3 wheel set
  • 964cup964cup Posts: 1,361
    964Cup wrote:
    215/35R19

    That's a fairly blingy wheel/tyre. Have you been on 'Pimp my Ride'?
    Actually it was the first tyre size that popped up on a web search when I was checking my maths for the large radius.

    My model isn't terribly accurate because it's treating the tyres in both cases as a torus. While a 23c tubular probably is a nearly-perfect torus, a car tyre plainly isn't. And I suspect I may have misremembered the formula, too (it was late, that's my excuse EDIT: no it wasn't, I have no excuse). In case you're *really* bored, here's some double-checked volumes:

    700x23c 0.87 l
    700x28c 1.31 l

    185/55R15 49.4 l
    195/45R16 54.6 l
    205/40R17 61.8 l
    225/40R18 79.6 l
    235/35R19 88.2 l
    305/30R20 158.6 l
  • unixnerdunixnerd Posts: 2,864
    Slightly OT, since breaking my wrist I struggle to get a decent pressure on my track pump. I have a big air compressor in the garage and a foot pump with a perished hose! Does anyone know where I can buy a foot pump with pressure gauge that will give me 120 without committing suicide?

    Failing that maybe a fitting for my air line with a Schrader / Presta fitting and a decent in-line gauge? I have one for inflating car tyres but the gauge is hugely off and I check it with separate Snap-On gauge. But that's no use for a Presta valve.
    http://www.strathspey.co.uk - Quality Binoculars at a Sensible Price.
    Specialized Roubaix SL3 Expert 2012, Cannondale CAAD5,
    Marin Mount Vision (1997), Edinburgh Country tourer, 3 cats!
  • There are adapters available to go presta/scrader which will get your compressor connected, and presta gauges available.

    In what way is the inline gauge off? The most important thing is if it is consistent with itself, eg real 90 always reads 110 for example you can mentally calibrate to go with that, so you know you are approximately OK then use a gauge to confirm rather than wild guessing when it feels OK.

    And theres always something like http://nextdaytyres.co.uk/details.aspx/ ... R-TOOL/290

    P.
    Giant Defy 2
    Large bloke getting smaller :-)
  • unixnerdunixnerd Posts: 2,864
    In what way is the inline gauge off?

    The needle on the gauge fell off :-) I find that most of these things are pretty cheap and inaccurate. My pressure gauge is a nice Snap-On on that cost a fair bit, most the things you see on garage forecourts and stuff would be within 15% on a good day. I'd rather use my track pump as there's no risk of making them dangerously hard but until my wrist heals fully it's awkward.
    http://www.strathspey.co.uk - Quality Binoculars at a Sensible Price.
    Specialized Roubaix SL3 Expert 2012, Cannondale CAAD5,
    Marin Mount Vision (1997), Edinburgh Country tourer, 3 cats!
  • Ah! That would make approximating rather challenging! Agree on forecourts - I carry my own gauge in the car. Looks like you want a prestaflator then http://nextdaytyres.co.uk/prestaflator/ is a slightly different link.

    Paul.
    Giant Defy 2
    Large bloke getting smaller :-)
  • unixnerdunixnerd Posts: 2,864
    Exactly what I need, thanks :-)
    http://www.strathspey.co.uk - Quality Binoculars at a Sensible Price.
    Specialized Roubaix SL3 Expert 2012, Cannondale CAAD5,
    Marin Mount Vision (1997), Edinburgh Country tourer, 3 cats!
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