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cars struggling up hills

edited March 2010 in The bottom bracket
I got an old ford puma for cheap and got my mate to boost the power a bit.

we did a test in his garage and i worked out that the power to weight ratio is 94.7 w/kg

a good climber will have 4-6 w/kg or more with drugs. think i'm around 2.8

BUT

when out on the bike I can go up 20% hills and cars much better than my puma struggle and make horrible noises. a merc stalled on a 15% today.

???

Posts

  • Ben6899Ben6899 Posts: 9,545
    It's to do with gear ratios and engine revolutions... 15% is one heck of a hill so I guess the merc may have been in 2nd gear at very low revs. If those revs drop too near to idle, then the car will stall.

    EDIT: a cyclist stalls at 0rpm, whereas 4 stroke combustion engine is much less tolerant and will stall at ~750-1100rpm.
    Ben

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  • ah.

    you mean the lowest gears are not low enough? if contador had only a 53 x 11 on a hill he would stall yes?

    can you tweak cars to give them 'granny gears''??
  • Steve_b77Steve_b77 Posts: 1,680
    You can but it'll probably cost more than a cheap puma is worth.

    New gear box or ooodles more power/torque is the only way to cope with big hills.

    See Pikes Peak race cars for how to get up a hill quickly.
  • bompingtonbompington Posts: 7,674
    As previous poster said, car engines stall at much higher revs than bikes (I'm sure most of us at some time have started pedalling from negative revs, i.e. going backwards) and the power/torque of any internal combustion engine at stalling speed is very low, that's what stalling means, it's when the torque is insufficient to overcome resistance.
    So any car stalling is down to driver error.
    Modern cars can climb hills with great ease, I drove up to Glenshee Devils_Elbow_Spittal_Of_Glenshee_profile.jpgthe other day, the last bit is about 200m climb in 2km, my car (Skoda, 2 litre diesel) was quite comfortable in 6th gear
  • Heckler1974Heckler1974 Posts: 479
    bompington wrote:
    the other day, the last bit is about 200m climb in 2km, my car (Skoda, 2 litre diesel) was quite comfortable in 6th gear

    You don't say how comfortable the people pushing your car were though :P
  • bompingtonbompington Posts: 7,674
    bompington wrote:
    the other day, the last bit is about 200m climb in 2km, my car (Skoda, 2 litre diesel) was quite comfortable in 6th gear

    You don't say how comfortable the people pushing your car were though :P
    Ahh, all the old Skoda jokes! I can tell you who's laughing now, whenever I see an Audi Quattro (see Clarkson's verdict) and I smugly think about how I'm driving more or less the same car at half the price
  • northernneilnorthernneil Posts: 1,549
    i hear what you are saying ... but ...

    .. I am guessing you ride a carrera ?
  • bompingtonbompington Posts: 7,674
    i hear what you are saying ... but ...

    .. I am guessing you ride a carrera ?
    No, Raleigh actually, and most of my cycle clothing comes from Aldi and Lidl.
  • rakerake Posts: 3,204
    maybe the cheap ford pooma not in good hea;lth.
  • nwallacenwallace Posts: 1,465
    It's on hills where I notice the quality of petrol.
    Difference between Shell and Tesco is needing to shift down to overtake on the Drumochter dual carriageway.going North when using Tesco.
    Do Nellyphants count?

    Commuter: FCN 9
    Cheapo Roadie: FCN 5
    Off Road: FCN 11

    +1 when I don't get round to shaving for x days
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