ucfdad

I have searched for a chart or something to give me an idea. 700 x 45 tires, sidewall says 60-80 and I weigh 230 pounds. Should I keep doing 70 psi like the LBS said or because of my weight should I do 80 PSI? Is the difference noticeable?

Thanks in advance for your help

Rootman

Try it and find out. If the tires are stiff enough and roll easy enough then stick with 70. Else, try 80 and see if the ride quality is good enough without jarring you to death.

Jewishcowboy

I would keep it at 80 cause there will be more pressure on the back tire. The front you could do 70 fine cause most of the weight is on the back wheel. I'm 140 lbs and keep mine at 80 in the back and it barely loses any pressure over a long ride

sail

Try it, probably a little harsher on bumps, worse in soft stuff and faster on flats.

ucfdad

Thanks. I am a new rider, so please excuse the stupid questions. I have a Bontrager floor pump. Should I trust the gauge on the pump or should I buy a separate gauge?

In reading the forums it appears that a loss of 10 lbs in a week is normal, so I need to get used to checking more frequently.

hokiefyd 

I'm 235 pounds on a good day (I go between 235 and 240) and I run less pressure than that (and on narrower tires!).

About a year ago, I wanted to find out the tire pressure required to achieve a 15-20% droop in sidewall height. This has been noted by those who have studied air pressure in cycling to be a good balance between rolling resistance, comfort, flat protection, etc. In other words, it's a good general target, from which you can adjust high or low depending on your individual preferences and riding conditions. So I sat on my bikes, with varying tire sizes and got into riding position. I leaned just slightly against a pole in my basement so as to not fall over, but to still be upright and in position on the bike. I had a family member measure the sidewall height loaded at varying air pressures, and I compared that to the sidewall height unloaded.

I found that about 40 psi in the front and about 60 psi in the rear was optimal for me, and this was generally without regard to tire size. Whether the sidewall is 32mm tall or 52mm tall, I'd get about a 20% droop/squish with 40F/60R. And I've run those pressures for hundreds of miles (they weren't far off from what I had already been using anyway), both on road and off, and I've been pleased at those pressures. The bike certainly rolls easier at higher pressures than I run, and it also rides worse as well. It's also more comfortable at even lower pressures than I run, but it's slower as well.

Play around with different tire pressures to see what feels best to you. Unless you're way underinflated and beating your rim up due to impacts against the surface through your tire, there really isn't a wrong answer here. It's what feels the best to you and best supports your goals.

Rootman

The pumps gauge should be close enough. I check tire pressure every ride. Takes just a few minutes. So, perhaps a separate gauge might come in handy. Also, get some chain lube and lube it maybe every 4 rides.

rumrunn6

also depends on what you are riding on. meaning pavement, hard dirt, crushed stone, softer soil based surfaces & or with or without a layer of fresh precipitation, maybe even snow? but for pavement, as mentioned above max in the rear is a good place to start, with 10-20 lbs less up front. you can feel free to use your pump's gauge, tire pressure accuracy isn't critical. trial & error will help you decide your preferred pressure(s). been experimenting with mine & the past year or so been surprised how low I can go with the front tire, especially on unpaved surfaces

subgrade

I am around 210 lbs and run 60 psi on 700x38C tires. Actually 65 psi is the maximum recommended for these tires (Schwalbe CX Comp), and haven't felt any need to exceed it, even on longer rides on pavement.

finch204

As others have said, it varies based on a number of factors. I used to ride around 110 psi on both tires on my Madone and it was a stiff ride. After reading on here that hokie runs different front and back tire pressures on his Roam, I did some research on tire pressures and eventually experimented a little with them. I discovered that 95 psi front and 110 psi rear works really well on my Madone with 23c tires. You'll have to try out different combinations and ride them out to get a feel for how the bike accelerates, stops and corners.

https://cyclingtips.com/2017/05/what...re-pressure-2/

rumrunn6

+1 for lowering the front pressure on road bikes too! amazing how little weight is on the front compared to the back, especially for riders like me that carry a heavy rear trunk on 25mm tires

Pompiere

This is my non-scientific method. I have a gravel driveway, so once I am out on the road, the dust wears off the tread and I can quickly see if I have the right pressure. It there is just a narrow band of clean tread, I can lower pressure by a few pounds. If the tread is wiped clean from edge to edge, then I need more air. I aim to have about 1/2-2/3 of the tread width in contact with the pavement. Generally, the rear needs about 10 psi more than the front.

fietsbob

Ripe watermelon feel, to the tire.

Doctor Morbius

Bicycle tire pressure calculator

livedarklions

Well, as long as the watermelon and tire are consenting, who are we to judge?

fietsbob

Not into data ? go tactile..

pjthomas

Exactly! Pump both tires near the high end. Find a rough stretch of road, not pot holed but cracked. Ride and you'll feel how harse the ride is. Let a little air out of the front tire and ride again. Keep doing this until you notice a sudden difference in the harseness. This is the ideal pressure for the front tire. You might have to inflate and start over a few times. Then do it for the rear.

rm -rf

The pump gauge is fine. Pressure losses depend on the tube thickness and the tire pressure -- I assume higher pressure tires drop a little faster.
When you pull off the pump, there's a hiss of escaping air. That's from the hose, not the tire.

With 43 mm tires at your weight, I'd try about 70-75 psi rear, and 55-60 front. (At 170 pounds, I use 45 psi rear and 38 psi front on a 40 mm tire! So you still have room to experiment with even lower pressures.)

When I look down at the front tire while riding, I can see a slight bulge outwards at the road contact.
Too high pressure: it's a bumpy ride, and often not any faster. Rough roads send a lot of buzz and vibration to the rider.
Too low: there's a risk of a "pinch flat". The wheel hits a sharp edged hole or larger sized rock, and the tire is squashed flat against the rim. The tube is folded in the middle and gets one or a pair of small slits where the rim mashes into it. Pinch flats are more likely at faster speeds and on sharper, larger obstructions.
Too low: the ride feels mushy and the steering response is slowed.

stuman74

I know this thread is from last year, but seems like lots of good recommendations. I just got new tires and want to set them as properly as possible.

I estimate that my total weight of me+bike+gear is about 270 to 280 lb. My tires are Bontrager H5 Hard Case Ultimate 700x38c and say 60-80psi on the tires.

Should I start out trying like 60 psi in the front and 70 psi in the back? Thanks!

hokiefyd 

That's higher than I'd start with, but it'll work. I'm right at the same weight as you (240 pounds, plus 30 pound bike), and I would run about 40 psi front and 60 psi rear when I had 38mm tires. I've since gone wider and have dropped the air pressure even more, but 40/60 might be a good place to start.

The H5s are pretty stiff tires to begin with, so anything you can do to soften the ride some is probably worth doing.