25mm vs 28mm tyre for safety to prevent risk of crashing

Tony Chopper-Kun

25mm has 130 psi,

then 28mm has 100psi , plus tyre fitting is less tighter than 25mm, without need of tyre lever, low psi needed for minimal

I planned to have pannier bag occasionally for heavy load or shopping

any difference to reduce risk of crashing on road, even rough road

peat

To reduce the risk of crashing, ride a bit slower around corners.

sungod

130psi in a 25mm!!! how heavy are you+bike?

if you want safety, use tubs instead of clinchers, or fat tyres, tubeless at low pressure with plenty of sealant

animal72

sungod wrote:

130psi in a 25mm!!! how heavy are you+bike

That. I run 80/85 on my 25s, the Mrs (who's a shortarse) runs 75/80.

Tony Chopper-Kun

sungod wrote:

130psi in a 25mm!!! how heavy are you+bike?

if you want safety, use tubs instead of clinchers, or fat tyres, tubeless at low pressure with plenty of sealant

tyre costs £7 , runs 100-130psi for 25mm, plus it is rubino

bbrap

Tony Chopper-Kun wrote:

tyre costs £7 , runs 100-130psi for 25mm, plus it is rubino

Not sure what the make of tyre has to do with it (whatever is printed on the side), but 130 psi in a 25mm tyre is too much unless you weigh in excess of 100Kg.

Tony Chopper-Kun

bbrap wrote:

Tony Chopper-Kun wrote:

tyre costs £7 , runs 100-130psi for 25mm, plus it is rubino

Not sure what the make of tyre has to do with it (whatever is printed on the side), but 130 psi in a 25mm tyre is too much unless you weigh in excess of 100Kg.

the problem with 25mm compared to 28mm, too much rolling resistance if pressure drop on 25mm compared to 28mm.

i tested 65psi on 35mm tyre and considered too slow in acceleration, its weight is 500g.

bbrap

Ok I'll try one last time. The pressure in your tyres is a compromise, too hard (too much pressure) and the ride will be uncomfortable, the bike will rattle about with less grip, and you will tire (get tired) quickly. The correct pressure will result in a comfortable ride, good grip and the effort you put in will result in you travelling at a good pace. Too soft and the rolling resistance will go up, you will puncture more frequently (pinch flats) and it will be hard work. The question is what pressure?
That depends on three things, tyre size, your weight (plus weight of bike), how you want the bike to feel.

As we have suggested 130 psi in a 25mm tyre is too hard and will give an uncomfortable ride. The only people who would need that pressure would be extremely heavy and need it to prevent pinch flats. If you are saying the rolling resistance on your tyres is excessive at 100 psi I suggest you get better tyres (for most people 90 psi is plenty in 25mm).

In 28mm you would use even less pressure at around 75-80 psi, be very comfortable, not get pinch flats and still not have excessive rolling resistance.

As you go up in size the tyres will naturally be heavier (as you have stated in your 35mm example), this will result in more effort required to spin up the wheels which in turn will be hard work. So the answer is to use the smallest tyre section that will give the comfort you require, 25 or 28 take your pick, just don't run them at 130 psi as it is not needed.

imposter2.0

130psi in a 25 is just bonkers. Your views on pressure and rolling resistance are directly at odds with reality.

Tony Chopper-Kun

does it mean pressure has no correlation with accelerations / climbing / maintain fast speed / energy efficiency?

Then any purposes of high pressure , if it deform a lot, won't it be slower?

apreading

You want about 15% tyre drop under normal loading as the de-facto standard. In wider tyres, you can run less pressure for the same percentage tyre drop. Gives you more comfort and a bigger contact patch on the road and the tyre deforming around surface changes and stones in the road actually helps maintain speed and is more efficient plus it reduces fatigue you feel due to road vibrations, so good all around.

If you are going to insist on running 130psi then you may as well stick to narrow tyres as you wont get the benefits of wide tyres and will get the negatives of a heavier tyre so the nett effect is that you will be worse off.

Tony Chopper-Kun

apreading wrote:

You want about 15% tyre drop under normal loading as the de-facto standard. In wider tyres, you can run less pressure for the same percentage tyre drop. Gives you more comfort and a bigger contact patch on the road and the tyre deforming around surface changes and stones in the road actually helps maintain speed and is more efficient plus it reduces fatigue you feel due to road vibrations, so good all around.

If you are going to insist on running 130psi then you may as well stick to narrow tyres as you wont get the benefits of wide tyres and will get the negatives of a heavier tyre so the nett effect is that you will be worse off.

weight seem almost negligible, 20g difference.

with some pressure drop on 25mm , while 28mm stay the same pressure as 25mm, but the rolling resistance whether the difference is too much on speed / acceleration / efficiency

apreading

Use this to calculate pressures: http://www.dorkypantsr.us/bike-tire-pre ... lator.html

Use the bottom box with either 40/60 weight distribution or 45/55. (Everyone gets confused by the top box because it is a calculator for the weight at EACH wheel INDIVIDUALLY so that is not your total weight)

trailflow

Tony what is you body weight ? That is the most important detail.

Dropping the pressures to 75-95 psi will add very little rolling resistance (especially at 25c). The tyre will then deform over bumps and grip the road better and that is what you want isn't it ? That's your original question ? Do you want to prevent a crash or just go fast in a straight line ?

a £7 tyre with a low 60tpi will not work better if pumped up rock hard.

Let some air out.

Tony Chopper-Kun

trailflow wrote:

Tony what is you body weight ? That is the most important detail.

Dropping the pressures to 75-95 psi will add very little rolling resistance (especially at 25c). The tyre will then deform over bumps and grip the road better and that is what you want isn't it ? That's your original question ? Do you want to prevent a crash or just go fast in a straight line ?

a £7 tyre with a low 60tpi will not work better if pumped up rock hard.

Let some air out.

97kg, it keeps increasing / decreasing 1/2/3kg every 3-4 months. i use 25mm vittoria rubino cuz it is cheap £7, and use it for £100 road bike with 7 speed. I will not add £15 tyre to beater road bike (parking it on any street with no risk of theft / ride fast enough as 15mph average speed)

I mainly ride as straight as possible especially hazards, plus overtaking and merging with traffic is quite often.
Even I go straight line, I run over a small stone, and front wheel move from side to side but maintaining control after that. Another one on roundabout, I control skidding on some small gravel while corning, there are a lot of of them on the road area. I would not rather ride over wet cumber stone with narrow tyre, riding slow make tyre go inside the gap.

lostboysaint

Well I'm 98kg and I run Michelin Pro 4 Endurance in 25mm and have 80 in the front and 90 in the rear. No pinch flats, no issues with speed, acceleration or rolling, cornering grip is very good and they're supremely comfortable.

voodooman

I weigh 105 kgs also with Michelin pro4 Endurance in 28mm. 87 psi on the front wheel, and 90 psi on the back (which is slightly over the recommended limit but hey ho). Very comfortable and smooth, really taking the edge off my bike (X-bow) which isn't the most forgiving.

fossyant

Try 23mm.