Different tires in the rear and in the back?

Phinx

I'm back with tome silly questions. This time, i'm interested if there is any benefit in putting different size tires. I've seen/heard of set-ups when the rider has a 2.1 or even 2.3 wide tire in the back and 2.0 in the front. Is there any bonus in such 'tuning'?

Da Mighty Chicken

Phinx wrote:

I'm back with tome silly questions. This time, i'm interested if there is any benefit in putting different size tires. I've seen/heard of set-ups when the rider has a 2.1 or even 2.3 wide tire in the back and 2.0 in the front. Is there any bonus in such 'tuning'?

Some riders like to have different tyres, but (someone maybe along soon to correct me) I think that some have the wider tyre at the front for grip and suspension benefits and a smaller/narrower tyre on the rear for acceleration where grip isnt so much of a problem as it is on the front.

So its certainly not an issue to mix and match tyres if thats what you want to do

robertpb

Narrow tyre on the back, because in a skid you can control a rear much easier and it cuts down drag.

Front less easy to control in a skid, so wider tyre gives a bit more grip giving more traction in the turns.

Phinx

Drag? :oops:

biff55

robertpb wrote:

Narrow tyre on the back, because in a skid you can control a rear much easier and it cuts down drag.

Front less easy to control in a skid, so wider tyre gives a bit more grip giving more traction in the turns.

couldn't put it better myself

drag ? :oops:

wearing womens clothes whilst riding , lipstick optional

Phinx

Strangely interesting, i might get in to that

Phinx

'Drag' as in 'aerodinamic drag'?

robertpb

We may be whippets but we're not that fast.

It's just contact with the planet that slows us down.

chris_sw

Phinx wrote:

'Drag' as in 'aerodinamic drag'?

Drag as in rolling resistance, like why road bikes use skinny slick tyres, because they roll quicker.

biff55

Phinx wrote:

'Drag' as in 'aerodinamic drag'?

drag as in the bigger the contact area between the tyre and ground ( ie from using a big tyre), the more it will slow you down.
more noticable on tarmac and other hard surfaces.
hence racing / road bikes have skinny 1 inch thick tyres.

antfly

I read that wider tyres actually roll faster on the road but then air resistance becomes a factor when you go above about 15mph so that`s why they have skinny tyres.

Airienteer

antfly wrote:

I read that wider tyres actually roll faster on the road but then air resistance becomes a factor when you go above about 15mph so that`s why they have skinny tyres.

The person who wrote what you read may have gotten a bit confused. A narrower tyre has less rolling resistance than a wider tyre, even when taking out air resistance. I could explain......but it's far too late for that!

Phinx

OK, i'll try to combine what was said so it makes a bit more sense to me.

a) Wider tire in the front and less wide in the back is the best option, because:
*Front needs more grip for control on turns, thus why a wider tire should be on
*Rear needs less grip to decrease drag and gives more freedom for control on skids, thus a less wide tire for the rear.

Am i there yet? Or did i loose the point?

77ric

nah phinx you didn't lose the point, in general big fat knobbly tyre up front and a narrower smoother rolling tyre tyre on the back.

Airienteer

Spot on. A front wheel drift is much harder to control than a rear wheel one. I personally run a 2.35 High Roller on the front and a 2.1 Ignitor on the back and find I don't need to change it all year round. I use this combination for anything from local evening rides on bridleways to trips to the Alps.

antfly

Airienteer wrote:

antfly wrote:

I read that wider tyres actually roll faster on the road but then air resistance becomes a factor when you go above about 15mph so that`s why they have skinny tyres.

The person who wrote what you read may have gotten a bit confused. A narrower tyre has less rolling resistance than a wider tyre, even when taking out air resistance. I could explain......but it's far too late for that!

Hmmm, I`m not sure you`re right there, i`m no expert but I have read more than once that wider tyres have less rolling resistance.

Atz

BTW when 77ric says a "smoother rolling" tyre he doesn't mean something like a small block 8 or jump/park tyre. Also remember that as the rear wheel is where you put the power down, you can lose a LOT of time and energy going up hill if you get a tyre that doesn't have enough traction.

antfly - I'd agree with the earlier poster, you heard wrong. More contact = more friction. The only time it's a benefit is in cornering.

PBo

You may want to edit the thread title....."rear" AND "back"?

I'm no expert, but wouldn't a fatter front tyre also be beneficial for braking - more contact?

.blitz

antfly wrote:

I have read more than once that wider tyres have less rolling resistance.

Wider tyres do roll better than narrow ones because the tyre is flattened a little under load which creates a flat contact area. At the same tyre pressure, a wide tyre and a narrow tyre have the same contact area. A wide tyre is flattened over its width whereas a narrow tyre has a slimmer but longer contact area.

The flattened area can be considered as a counterweight to tyre rotation. Because of the longer flattened area of the narrow tyre, the tyre loses more of its 'roundness' and produces more deformation during rotation. However, in the wide tyre, the radial length of the flattened area is shorter, making the tyre 'rounder' and so it rolls better.

Road tyres are generally inflated to a higher pressure to reduce this deformation and so improve rolling resistance.

antfly

Thanks for the explanation and for confirming what I thought.

Phinx

.blitz,

At the same tyre pressure, a wide tyre and a narrow tyre have the same contact area

This might be truth, but it does not mean it is applicable both off-road and on the road, or we would be using same tires everywhere. Don't forget that tread of the tire counts up to a lot of rolling resistance. There is no need to be a genius to feel the difference between skinny tires and MTB tires while riding on tarmac.

I just don't think that conditions on the road and off-road can be so closely compared, .blitz. The low profile tires on road bikes are made to have as little resistance as possible, while MTB tires give you as much grip with the terrain as possible.

RichMTB

But what blitz is saying is correct, if the only parameter changed is tyre width (same pressure, same tread pattern, same weight applied to tyre) then a fatter tyre will roll better.

In the real world not many of us have ever ran a 2.0" slick at 45psi back to back with a 1.0" slick at 45psi. The comparison most of us have experienced is a 1.0" slick at 65psi vs a 2.1" knobbly at 40psi so of course the skinny tyre rolls faster

Th3 Firestarter

biff55 wrote:

drag ? :oops:

wearing womens clothes whilst riding , lipstick optional

This applies if you're a dirt jumper, they all wear skinny girls jeans, and jeggins!