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BHP and tread/type/pressure

900 views 12 replies 6 participants last post by  wildmurphy  
#1 ·
I'm currently training for a tri and when swimming length after length my mind often drifts to my MGF and as a result questions arise...this was what cropped into my head at 6.15 this morning !!

We all (or most of us) change a throttle bottle here or a larger air pipe there just to squeeze out a little more BHP or throttle response.

I was wondering whether the following would make an iota of difference to performance, not handling, just straight line grunt:

Wheel size
Tyre size
Tyre type/brand
Tyre tread (wear)
Tyre inflation PSI

My gut feeling is that the only aspect that may make a difference is if they are under inflated and if this is true, perhaps this is where we should be paying closer attention...
 
#3 ·
You could demo the difference to yourself if you wished - fit mtb knobblies on your tri bike and see if you can feel a difference.

If you really mean straight line only then check out the tyres on most land speed vehicles - narrow, smooth, very high pressures; all to reduce rolling resistance. Also normally faired in to reduce drag.

Drag racers are almost exact opposite - minimal fronts as they are rarely on the ground and big, wide, soft, low pressure rears to maximise the grip for accelleration over very short distances.

Never done a tri myself but some time trialling a long time ago and some track (velodrome) events. Mainly 700 x 20 - 23 at 100 psi or more - again, for reduced rolling resistance.

What tri distances are you training for? Have you done any/many yet or is this a new venture?
 
#4 ·
scuzza said:
Wheel size
Tyre size
Tyre type/brand
Tyre tread (wear)
Tyre inflation PSI

My gut feeling is that the only aspect that may make a difference is if they are under inflated and if this is true, perhaps this is where we should be paying closer attention...

all will affect straight line grunt. but the differences would be minimal and only useful to people involved in racing or competing in santa pod etc. for most everyday environments the differences wouldnt be too noticeable.

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#5 ·
Sprinter said:
You could demo the difference to yourself if you wished - fit mtb knobblies on your tri bike and see if you can feel a difference.

If you really mean straight line only then check out the tyres on most land speed vehicles - narrow, smooth, very high pressures; all to reduce rolling resistance. Also normally faired in to reduce drag.

Drag racers are almost exact opposite - minimal fronts as they are rarely on the ground and big, wide, soft, low pressure rears to maximise the grip for accelleration over very short distances.

Never done a tri myself but some time trialling a long time ago and some track (velodrome) events. Mainly 700 x 20 - 23 at 100 psi or more - again, for reduced rolling resistance.

What tri distances are you training for? Have you done any/many yet or is this a new venture?


I used to run marathons but it's time to give the old joints a break as i dont want new hips at 40 !! - I'm built more for triathlon so have been doing sprint and olympic distances for the past couple of years - would love to attempt and Ironman but that really is beyond me i'm sure. Strangely enough the cycling is what i'm most novice at but is my strongest sector. Lactic build up is a killer thougj but i guess you know all about that.
 
#6 ·
MG Deano said:
all will affect straight line grunt. but the differences would be minimal and only useful to people involved in racing or competing in santa pod etc. for most everyday environments the differences wouldnt be too noticeable.
so wider wheels would give more grip and therefore acceleration ?
 
#9 ·
width of wheels does not affect friction constant.

Neither will affect acceleration.( i believe)

Width of wheels affect handling in different weathers and cornering.

Size (ie diameter) will affect acc and top speed.

though i'm sure ten foot wide tires might effect the something or other of rotation, making it need more torque - difference between 165 and 225? Nowt.
 
#10 ·
wildmurphy said:
though i'm sure ten foot wide tires might effect the something or other of rotation, making it need more torque - difference between 165 and 225? Nowt.
if there is a difference between normal width wheels and 10ft wide wheels then there will be a difference between 165 ans 225. its just the difference might be so small its practically unnoticeable.

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