3 replies to this topic

[The Wrench]

Having written about mountain bike tires last month I thought it only fitting to add my chart of road bicycle tire pressure settings here as well. Proper tire air pressure will increase the performance of any road bike. It's the fastest, easiest, and cheapest tune-up/upgrade you can perform on your bike. Do yourself a favor and set your tire air pressure before your next road ride and see what a difference it makes.

Let's talk about road tires:

• Overinflated tires:

• Reduce rolling resistance but you'll need ultra smooth roads to notice any potential gains
• Give a harsher feel to your ride if you encounter bumps

[*]Underinflated tires:

• Will cause you to have handling/control problems
• Could damage the rims on your bicycle
• Increase rolling resistance, requiring more effort on your part to propel your bicycle
• Cause uneven wear patterns on your tires that could lead to premature failure

[*]In case you've ever wondered about the tire inflation capacities of CO2 cylinders:

• 700 x 23 Tire size
  

• 12 gram cylinder will inflate up to 94 psi
• 16 gram cylinder will inflate up to 130 psi
• 25 gram cylinder - NOT recommended for road tire use

[*]700 x 26 Tire size

• 12 gram cylinder will inflate up to 90 psi
• 16 gram cylinder will inflate up to 123 psi
• 25 gram cylinder - NOT recommended for road tire use

The factors to consider when selecting tire pressure are:

• Rider weight
  

• What you weigh is important in determining air pressure. Don't worry so much about what the bicycle weighs before you get on it.
• There's a certain amount of deflection in every tire profile that's optimal for balancing grip, efficiency, comfort and durability. That deflection is based on the tire's construction and the weight of the rider.

[*]Road conditions

• Unless you ride on perfectly smooth road surfaces you're going to have to account for the bone-rattling bumps along your route.

[*]Tire size

• The front and rear tire should be set at the same air pressure level.
• Never simply squeeze a tire to ascertain its pressure level. Invest in a good quality pump with a built-in gauge and/or a hand held bicycle tire pressure tool.

Use this handy chart as a good starting point for road bike tire pressures
Riders weighing below 100lbs-45kg should inflate to minimum pressure indicated on tire sidewall.
Riders weighing above 190lbs-86kg (***) should inflate to maximum pressure indicated on tire sidewall.

Rider weight (lbs-kg)	Clincher 700x28/32c	Clincher 700x25c	Clincher 700x23c	Clincher 700x20c	Clincher 650x23c
100lbs-45kg	58 psi(4 bar)	73 psi(5 bar)	87 psi(6 bar)	87 psi(6 bar)	87 psi(6 bar)
110lbs-50kg	58 psi(4 bar)	73 psi(5 bar)	87 psi(6 bar)	87 psi(6 bar)	87 psi(6 bar)
120lbs-54kg	62 psi	77 psi	91 psi	91 psi	91 psi
130lbs-59kg	66 psi(4.5 bar)	81 psi	95 psi(6.5 bar)	95 psi(6.5 bar)	95 psi(6.5 bar)
140lbs-64kg	72 psi	87 psi(6 bar)	101 psi	101 psi	101 psi
150lbs-68kg	76 psi	91 psi	105 psi	105 psi	105 psi
160lbs-73kg	80 psi(5.5 bar)	95 psi(6.5 bar)	109 psi(7.5 bar)	109 psi(7.5 bar)	109 psi(7.5 bar)
170lbs-77kg	85 psi	100 psi	114 psi	114 psi	114 psi
180lbs-82kg	87 psi(6 bar)	102 psi(7 bar)	116 psi(8 bar)	116 psi(8 bar)	116 psi(8 bar)
190lbs-86kg	95 psi(6.5 bar)	109 psi(7.5 bar)	118 psi	118 psi	118 psi
200lbs-90kg	***	***	***	***	***
210lbs-95kg	***	***	***	***	***
220lbs-100kg	***	***	***	***	***

[Brenton]

Great post. I've always wondered what would happen if I used a canister until it was empty. I never knew what the full volume would be. I will need to inspect my canisters more closely.   Got a q for you. Recently continental have come out and now spec some of their 700c tires at 24mm, and claim that the difference of 1mm over 23mm tires actually can INCREASE tire speed. Always though that more rubber in contact with the road = more grip = more resistance= slower top speed. Can you explain?   "The new Grand Prix marks the trend toward wider tires in performance cycling. Wider tires roll easier, yield higher mileage and offer more comfort and grip, therefore the new Grand Prix profile is 24mm." [http://www.conti-onl...d_prix_en.html]   cheers   Brenton

[Ulysses N. Owen]

Brenton, Thanks for your question. Our resident Wrench perused the Continental information concerning the new 24mm tires and concluded that creative marketing and 'new product craze sensationalizing' is much to blame for the claims of INCREASED tire speed. The word TREND appears repeatedly in their ad campaigns. Your own assessment of more rubber in contact with the road = more grip = more resistance = slower top speed is partially true while Continental's claim of more rubber in contact with the road = more grip = higher top speed is partially true as well. So how can you both be correct you may ask? Think of the rear tires on any drag strip race car you've ever seen. There is a MASSIVE amount of rubber in contact with the road equaling MASSIVE grip which creates the greatest potential for the HIGHEST SPEEDS. So we see that the size of the tire contact patch IS the reason any vehicle (drag strip race car OR bicycle) is propelled forward. Now we must consider what engine is being utilized to push those tires. In the case of the drag strip race car the tire contact patch can be massive because the engine (and gear box) is capable of pushing such large tires. In the case of your bicycle, YOU are the engine and the size of the tire contact patch must be able to transfer YOUR pedaling power to propel the bicycle forward. Understanding this, it is easy to see how many riders have a preferred tire width size that they feel is the perfect mix of speed, traction, comfort, and performance.

[Australianbike]

Great post. This is a useful chart shared for good starting point of tire pressures of road bikes.