Can i use a fatter rear tyre than on the front ?

robinta
robinta Posts: 211
edited July 2009 in MTB general
At the moment i'm running a 2.25 nobby nic rear with a 2.2 specialized purgatory up front( this is more like a 2.3). The spesh ( which i changed from another NN) doesn't bite or corner as well as i'd hoped and i dont think is worth using at this time of year as its quite slow. I've got a conti mountain king i was going to try but its the 2.2 so will certainly be narrower than the nobby. Will this be a problem as usually the front tyre should be fatter than the rear ?

Comments

  • nicklouse
    nicklouse Posts: 50,675
    might not be narrower as not all tyres are measured the same.

    try it.
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  • Hercule Q
    Hercule Q Posts: 2,781
    it shoudn't be a problem as long as you have the clearence for it

    pinkbike
    Blurring the line between bravery and stupidity since 1986!
  • chorscroft
    chorscroft Posts: 254
    I run a bigger tire in the rear than up front mostly for the cushioning effect of a big tire out back and the nimbleness of a smaller tire up front.

    There's not necessarily anything wrong with it, it's down to personal preference.
  • dave_hill
    dave_hill Posts: 3,877
    If you're going to run mismatched tyres It's more normal to run a wider one at the front, the reasoning being that a bigger tyre at the front gives you more cornering control and grip.

    It's always a good idea to have control and grip at the front because a sliding/non-steering front wheel is very difficult to control.
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  • ads4
    ads4 Posts: 698
    I'm riding a fatter front :)
    Adam.

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  • paul.skibum
    paul.skibum Posts: 4,068
    I have a fatter rear for the cushioning plus my NBX isn't as good a steering tyre as the Resolution so it makes sense to run smaller at front.

    By the way anyone want to argue why motorbikes run fat at back and skinny front if the above arguement holds any water?!
    Closet jockey wheel pimp whore.
  • Chaz.Harding
    Chaz.Harding Posts: 3,144
    +1 for what dave_hill said. A rear slide is MUCH easier to control than a front wheel slide!! :oops:

    :lol::lol::lol:
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  • Chaz.Harding
    Chaz.Harding Posts: 3,144
    By the way anyone want to argue why motorbikes run fat at back and skinny front if the above arguement holds any water?!
    For a couple of reasons, actually. Motorbikes have insanely powerful motors for their weight. It's not uncommon to see 150hp for 250kgs. The large rear tyre provides grip for all that power, and as most of the steering is done by leaning, the front doesn't have to be huge.

    It's also a weight factor. The skinnier fronts weigh ALOT less than the rears. And aerodynamics too. A skinny front will give better fuel efficiency, and more speed.

    Push-bikes are different. Rear grip isn't really an issue, as we aren't so powerful, we regularly do burnouts... Lol. We may loose grip from time to time, but our power-to-weight ratio isn't anything like the superbike's... We'd be doing well to get 40hp/tonne. And that would be world class cyclists at minimum weight and sprint power. Superbikes can easily exceed 700-800 bhp/tonne.

    That's a few reasons why :lol::wink:
    Boo-yah mofo
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  • Northwind
    Northwind Posts: 14,675
    dave_hill wrote:
    If you're going to run mismatched tyres It's more normal to run a wider one at the front, the reasoning being that a bigger tyre at the front gives you more cornering control and grip.

    It's always a good idea to have control and grip at the front because a sliding/non-steering front wheel is very difficult to control.

    Yup. But if the front tyre has enough grip already, that's not a worry.
    Uncompromising extremist
  • Northwind
    Northwind Posts: 14,675
    By the way anyone want to argue why motorbikes run fat at back and skinny front if the above arguement holds any water?!

    Various reasons. With motorbikes, the size of the tyre has a big impact on the turning characteristics, so for the steering tyre (ie front) you want a smaller, faster turning profile. That's a non-issue on a pushbike.

    It's actually not so much about power as you'd think- a litre sportsbike stops faster than it goes, a Fireblade takes 6 seconds to get to 100 but less than 5 to get back to zero. It generates IIRC the equivalent of 220bhp of braking force. So, the front tyre works harder at full brake than at full power.

    On the other hand, few sportsbike riders have the capability to stop that fast, while they all have the capability to open the throttle too hard, so the rear tyre does deal with the same forces more often.

    But, it does have a lot to do with cornering forces, leaned over the tyre's dealing with the turning forces then you try and accelerate out of the corner, so you're loading up with a second force- you can slide the rear wheel of a motorbike with about 11bhp if you try hard enough, never mind 160bhp.

    It also has a bit to do with fashion 8) Most bikes with 200 or 190 section rear tyres handle better with a 180 on the rear, without compromising much on grip, but they don't look as potent.

    Oh, also it's commonplace for the smaller front tyre on a motorbike to be stickier than the larger rear tyre- my own diablos use a different compound and construction on the rear than on the front.

    But one thing that's the same for both pushirons and proper bikes is that the rear tyre and front tyre do totally different jobs. The front brakes and initiates turns, the rear pushes and brakes. What works at one end doesn't always work at the other, which is why some tyres have different designs or directions front or rear, or why some tyres work better on one end than the other.
    Uncompromising extremist
  • passout
    passout Posts: 4,425
    It's fine as long as your front tyre is grippy enough - which is to do with compound, tread and not just size.
    'Happiness serves hardly any other purpose than to make unhappiness possible' Marcel Proust.
  • Northwind
    Northwind Posts: 14,675
    passout wrote:
    It's fine as long as your front tyre is grippy enough - which is to do with compound, tread and not just size.

    Sense and relevance in one post, this could shake the internet to its foundations :lol:
    Uncompromising extremist
  • dave_hill
    dave_hill Posts: 3,877
    By the way anyone want to argue why motorbikes run fat at back and skinny front if the above arguement holds any water?!

    Yes, as any decent motorcyclist will tell you, the front tyre is only there for effect, as everyone knows motorcycles are designed to be ridden on the rear wheel alone and never below 70mph.
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  • robinta
    robinta Posts: 211
    So. If the answer to the question is 'its ok for a front tyre to be narrower as long as it has more grip' will the mountain king have more grip than the nobby nic ? I know i could just try it myself, but I fit all my tyres with sealant now and its a lot of effort to keep changing tyres for a short trial (i know diva alert ! ). Plus, i dont want to find out the painfull way !
  • passout
    passout Posts: 4,425
    Put a Panaracer Cinder 2.25 folding up front - that will be much more grippy, although it's not exactly fast.

    I don't think you'll notice TBH.
    'Happiness serves hardly any other purpose than to make unhappiness possible' Marcel Proust.
  • mhuk
    mhuk Posts: 327
    Aren't Nobby Nics often run up front with the lesser grip tyre (e.g. racing ralph) run on the back? If I were to run a fatter tyre it'd be on the front not the back but I've nothing bigger than 2.2 - ignoring any differences between brands and real widths :)
  • robinta
    robinta Posts: 211
    I`ve always got the impression that the Cinder is quite slow - it also might be too heavy for what I want (sorry)
  • Grimy
    Grimy Posts: 111
    I run a Cinder on the rear and a fire on the front. Works fine for me, changing the the rear tyre to something with a little more volume to cushion the blows made zero difference to the way the front tyre grips, and why should it?

    I can see where your concern is, but your applying principles based on a car, not a bike.