FAQ’S


Frequently Asked Tyre-Questions

Customers have a many queries on the fitment, usage & technology of bicycle tyres and tubes and we have tried to club them and clarified the often repeated queries in this section. Even though it covers most of the points, in case of any clarification that is not covered in this section we request you to kindly contact us.

What is a bicycle tyre?

A tyre is a torroidal / ring shaped component that covers the rims of the bicycle and transfers the load of the bike and rider to the ground to provide traction. They can be pneumatic or solid. Mostly pneumatic tyres are used in bicycles for better riding comfort. Pneumatic tyres can be either tubular or tubeless. A tyre that needs a tube for holding air is called Tubular tyre. If the air can be held without tubes then it is a Tubeless tyre.

What is the meaning of size marked in a bicycle tyre?

Bicycles evolved over a period of time in many countries. Initially the sizes were marked in inches.

Example 1 – 28 x 1 3/8

First number – 28 – is the approximate outer diameter (OD) of the tyre and the second number 1 3/8 is the approximate section width (SW) of the tyre under standard inflated conditions.

Example 2 – 28 x 1 5/8 x 1 3/8

First number – 28 – is the approximate OD of the tyre, second number 15/8 is section height (SH) & 1 3/8 is SW. These are narrower tyres than the standard for the same rim.

The OD is very approximate as the real OD depends on the section width also. If there are two tyres say

26 x 1.75 &
26 x 3.5

then, the OD of the first tyre will be about 25.7” and the second tyre will be 29.1”

In the above size markings, user can’t decide whether it will fit his/her bicycle rim without experience. To standardize the size markings, manufacturers are moving towards ETRTO size markings. In many countries both the inch marking and ETRTO markings are currently being used.

ETRTO size marking

Example – 37-622

First number 37 is SW in mm & second number 622 is inner diameter (ID). This ID will give the indication to the user on rim fitment too.

Graphical explanation of the sizes are given below

What is the ETRTo equivalent of 27.5 x 2.1?

Its equivalent is 54-584. Please find below the compiled list of various ETRTO sizes and their equivalents in Inch and French marking. This is for reference only

ETRTO Inch French
7″ 47-93 7 x 1 3/4
8″
47-94 20 x 47-50 / 8 x 2
50-94 20 x 50
54-110 8 x 2 1/8 / 8 1/2 x 2
32-137 8 x 1 ¼
10″ 54-152 44-194 10 x 2 10 x 1 5/8
11″ 47-222 11 x 13/4
12″
12″ 47-203 12 1/2 x 1.75 / 12 1/2 x 1.90
54-203 12 x 1.95
57-203 12 1/2 x 2 1/4 R 300 x 55A
62-203 12 1/2 x 2 ¼
32-239 12 1/2 x 1 3/8 x 1 1/4 300 x 32A
57-239 12 1/2 x 2 ¼ 300 x 55A
14″
57-251 14 1/2 x 2 ¼ 300 x 55A
47-254 14 x 1.75 / 14 x 1.90
40-279 14 x 11/2 350 x 38B
37-288 14 x 1 5/8 x 1 3/8 350A / Balloon 350 x 32A
40-288 14 x 1 5/8 350 x 38A
32-298 14 x 1 ¼ 350A / 350 x 32A
44-288 14 x 1 5/8 x 1 3/8 350A / 350 x 42A
32-298 14 x 1 ¼ 350A / 350 x 32A
16″
40-305 16 x 1.50
47-305 16 x 1.75 16 x 1.90
54-305 16 x 1.95 16 x 2.00
57-305 16 x 2.125
40-330 16 x 1 1/2 400 x 38B
28-340 400 x 30A
32-340 16 x 1 3/8 x 1 1/4 400A 400 x 32A
37-340 16 x 1 3/8 x 1 1/4 400 x 35A 400A Confort
400A Ballon 400A 1/2 Ballon
44-340 16 x 1 5/8
28-349 16 x 11/8
32-349 16 x 11/4 NL
37-349 16 x 1 3/8
17″
32-357 17 x 1 1/4
37-369 17 x 1 1/4
18″
28-355 18 x 1 1/8
40-355 18 x 1.50
47-355 18 x 1.75 18 x 1.90
37-387 18 x 1 3/8
40-387 18 x 1 1/2
28-390 18 x 1 1/8 450 x 28A 450A
450 x 35A 450A 450A
37-390 18 x 1 3/8 Confort 450A Ballon 450A 1/2Ballon
55-390 450 x 55A
57-390 450 x 55A 450A
37-400 18 x 1 3/8
20″
54-400 20 x 2 x 1 3/4 20 x 2F4J
28-406 20 x 1 1/8
32-406 20 x 1.25
35-406 20 x 1.35
37-406 20 x 1 3/8
40-406 20 x 1.50
44-406 20 x 1.625
47-406 20 x 1.75 20 x 1.90
50-406 20 x 2.00
54-406 20 x 2.00
57-406 20 x 2.125
54-428 20 x 2.00
40-432 20 x 1 1/2
37-438 20 x 1 3/8 500A
40-438 20 x 1 3/8 500 x 38A
28-440 500 x 28A 500A 500A Standard
40-440 20 x 1 1/2NL 500 x 38A
28-451 20 x 1 1/8
37-451 20 x 1 3/8 B.S.
22″
44-484 22 x 15/8 x 11/2
25-489 22 x 1.00
37-489 22 x 1 3/8 NL
40-489 22 x 1 3/8 x 1 1/2
50-489 22 x 2.00
28-490 550 x 28A 550A 550A Standard
32-490 22 x 1 3/8 x 1 1/4 550 x 32A 550A
37-490 22 x 13/8 550 x 35A 550A Confort
550A Ballon 550A 1/2 Ballon
37-498 22 x 1 3/8 x 1 1/4 550 x 35A 550A Confort
32-501 22 x 1 1/4
37-501 22 x 1 3/8
24″
40-507 24 x 1.50
40-507 24 x 1.625 24 x 1.75
40-507 24 x 1.75 24 x 1.85/1.90
40-507 24 x 1.85
50-507 24 x 1.90/2.00 24 x 2.00 24 x 2.125
54-507 24 x 2.10
57-507 24 x 2.125 24 x 2.00
60-507 24 x 2.35
44-531 24 x 1 5/8 x 1 1/2
40-534 24 x 1 1/2
25-540 24 x 1.00
32-540 24 x 1 3/8 x 1 1/4 24 x 1 3/8
37-540 24 x 1 3/8
40-540 24 x 1 3/8 x 1 1/2
22-541
25-541 600 x 25A
28-541 600 x 28A 600A 600A Standard
32-541 24 x 1 3/8 x 1 1/4 N4 600 x 32A
37-541 600 x 35A 600A Confort
600A Ballon 600A 1/2 Ballon
26″
25-559 26 x 1.00
35-559 26 x 1.35
37-559 26 x 1 5/8 x 1 3/8 26 x 1.40
40-559 26 x 1.50
44-559 26 x 1.625 26 x 1.50/1.75
47-559 26 x 1.75 26 x 1.85/1.90
50-559 26 x 1.90 26 x 1.95 26 x 1.90/2.00 26 x 2.00/2.10
54-559 26 x 1.95 26 x 2.10 26 x 2.125
57-559 26 x 2.125 26 x 2.20/2.25
60-559 26 x 2.35
62-559 26 x 2.50
20-571 26 x 3/4 650 x 20C
23-571 26 x 7/8 650 x 22C
40-571 26 x 1 1/2 CS 26 x 1 3/8 x 1 1/2 NL 26 x 1 5/8 x 1 1/2 650 x 35C 650 x 38C
47-571 26 x 1 3/4 650 CS confort 650 x 45C
54-571 26 x 2 x 1 3/4 650 x 50C
28-584 26 x 1 1/8 x 1 1/2 650 x 28B
32-584 650 x 32B
35-584 26 x 1 3/8 x 1 1/2 650 x 35B 650B Standard
37-584 26 x 1 1/2 x 1 3/8 26 x 1 1/2 650 x 35B
40-584 26 x 1 5/8 x 1 1/2 650 x 42B 650B Semi-Confort 650B 1/2 Ballon
20-590 650 x 20A
25-590 26 x 1 1/8, 1 1/4 26 x 1 3/8 – 1 1/4 650 x 32A
28-590 26 x 1 1/8 650 x 28A
32-590 26 x 1 1/4 26 x 1 3/8 x1 1/4 650 x 32A
35-590 26 x 1 3/8 650 x 35A
37-590 26 x 1 3/8 650 x 35A 650A
40-590 26 x 1.50 28 x 1 3/8 x 1 1/2 650 x 38A
44-590
32-597 26 x 1 1/4
27″
40-609 27 x 1 1/2
20-630 27 x 3/4
22-630 27 x 7/8
25-630 27 x 1.00 27 x 1 1/16
28-630 27 x 1 1/8 27 x 1 1/4 Fifty 27 x 1 1/4
32-630 27 x 1 1/4
28/32-630 27 x 1 1/4
35-630 27 x 1 3/8
27.5″ 54-584 27.5 x 2.10
28″
18-622 28 x ¾ 700 x 18C
19-622 700 x 19C
20-622 28 x ¾ 700 x 20C
22-622 28 x 7/8 700 x 22C
23-622 28 x 7/8 700 x 23C
25-622 28 x 1.00 700 x 25C
28-622 28 x 1.10 700 x 28C
30-622 28 x 1.20 700 x 30C
32-622 28 x 1.25 700 x 32C 700C COURSE
35-622 28 x 1.35 700 x 35C
37-622 28 x 1.40 700 x 35C
40-622 28 x 1.50 700 x 38C
42-622 28 x 1.60 700 x 40C
44-622 28 x 1.625 700 x 42C
47-622 28 x 1.75 700 x 45C
50-622 28 x 1.90, 28 x 2.00
60-622 28 x 2.35
32-635 28 x 1 1/2 x 1 1/8 770 x 28B 700 x 28B 770B COURSE
40-635 28 x 1 1/2 28 x 1 1/2 x 1 3/8 700 x 38B 700 x 35B 700 Standard 700B Standard
44-635 28 x 1 5/8 x 1 1/2 700 x 40/42B
28-642 28 x 1 3/8 x 1 1/8 700 x 28A
37-642 28 x 1 3/8 700 x 35A
29″ 54-622 29 x 2.10

How to select the tyre width based on rim width?

Tyre & rim matching
If the inner diameter of the tyre matches the bead seat diameter, then the tyre will fit the rim. In addition the width of the tyre should match the rim width. Rim width (mm) and the matching tyre width are covered in ETRTO and below is the list of crotchet rim widths and the matching tyre widths.

Tire section width

Rim width(mm) 18 20 23 25 28 32 35 37 40 44 47 50 54 57 60 62
13c x x x x
15c x x x x
17c x x x x x x x x x
19c x x x x x x x x x x x x
21c x x x x x x x x x x
23c x x x x x x x x x
25c x x x x x x x
27c x x x x x x
29c x x x x x

This covers most of the usage, however, it is not exhaustive and many more probabilities are there due to changing scenario in design and usage of bicycles.

What is the significance of various tyre dimensions?

Tyre Outer Diameter :

  • The higher outer diameter has the following benefits for the rider
  • Less stiff and hence comfortable ride
  • Higher road contact & hence better grip
  • Better manoeuvrability
  • Faster speed & Easier rolling on tougher terrain
  • The negative is that the tyre weight will be slightly more
  • Due to the above reasons, both the 27.5 & 29” tyres are becoming increasingly popular these days

Narrow section width tyres :

Advantages

  • Easier to accelerate & hence preferred in racing

Disadvantages

Needs higher inflation pressure and hence rides are less comfortable

Wider section width tyres :

Advantages

  • Better grip on the rough terrain
  • Needs lower inflation pressure and hence the ride is more comfortable
  • Better rolling resistance than narrower tyres under the same inflation pressure as the
  • deflation on the contact area is lower
  • The negative is that the tyre weight will be slightly more

Disadvantage

Heavier than the narrow width tyres

What are the components of a tyre and their key functions?

Tread :

The outer layer of the tyre is made of rubber compound that surrounds the casing and bead rings. The function of the tyre is to grip the surface, convert the pedalling power to vehicle movement, protect the casing and absorb the shock while riding.

Tread is the portion that touches is the ground. It consists of tread patterns which are designed to meet the service conditions such as racing, city road, and off-road.

The tread component that extends to the side of the tyre is called as Sidewall. If the sidewall is made of rubber compound then the tyres are called as Gum-wall tyres.

If there is no rubber tread on the sidewall, the tyres are called as Skin-wall tyres. A sub-tread made of special cushion rubber compound is used in Puncture resistant tyres.

Casing :

Casing is the skeleton of the tyre which gives the proper shape to the tyre and it carries the load. It consists of rubberized textile usually nylon. The density of the textile is measured in TPI (threads per inch) which is designed as per the needed performance of the tyre. Number of textile layers can be 2 or 4 depending upon the service requirements.

Belt :

Higher density textile or aramid belt which increases the puncture resistant.

Beads :

Beads are bands of high tensile material in rubber compound. Beads are stronger and inelastic. They provide the mechanical strength to fit the tyre to the rim and hold on to it.

Wired tyres :

A rigid wire, usually copper / bronze coated steel wire is used for bead. They are also called as Clincher tyres.

Foldable tyres :

A strong but foldable bead usually made of aramid fibres (Kevlar) is used for bead. Aramid beads are stronger but they are lighter by about 50 – 90 grams compared to wired tyres.

What is a clincher tyre?

The tyres that uses bead rings (could be steel or Kevlar) which clinches to the rim is a clincher tyre. Tubes are used for these tyres for inflation.

What is a slick tyre?

A slick tyre is a narrower tyre which has a practically a plain tread. This gives better acceleration and good grip on smooth roads even if it is wet. However, on a rough terrain or on loose soil roads, the grip & control is very poor.

What is a tubeless tyre?

In a tube less tyre the tyre & rim are designed to make the tyre – rim assembly air tight. Air is retained in this system without tube. Both the tyre and rims are made with special design.

Advantages :

  • No separate tube is needed
  • Better in speed, comfort & grip
  • Compatible for puncture protection liquid usage

What impacts tyre performance?

  • The nature and quality of the rubber compound
  • Tread pattern design
  • Construction of casing – textile type (Nylon/Cotton/Polyester) and TPI
  • Tyre Engineering such as tyre contour, number of layers of textiles, bead wire construction and gauges
  • Tyre rolling resistance
  • Type & quality of the inner rubber tube
  • Surface of ride

What is the meaning of Rotation arrow & how to use them to get a better performance?

The arrow denotes the rolling direction. Fitment of the tyre aligned with the movement of the bike will make the rolling easier.

However, if the same tyres are used in front and rear, especially for a MTB, fitment of the rear tyre opposite to the rolling direction will give better grip and control.

What is rolling resistance?

Bikes are pedalled using manual power and hence ideally one would like to convert the total manual power to bike movement. However when the tyre rolls on the surface due to friction some of the energy is lost in overcoming it. This loss is termed as rolling resistance.

During a bike ride there are other factors that will add to the rolling resistance. They are Rolling resistance increases gradually and proportionately with respect to bike speed.
Air resistance – At lower speed, its impact is lower; however on higher speeds such as 15 miles per hour, this becomes the major resistance.

Gradient or slope resistance – This occurs when riding uphill and it increases steeply and proportionately to bike speed.

What is puncture and how it can be prevented

Puncture is damage to the air tight compartment resulting in deflation. Factors that have to be kept in mind for reducing the risk of deflation are :

  • Good quality tyre & tube
  • Puncture resistant tyre (with a puncture guard / protection tyre)
  • Maintaining correct inflation pressure
  • Usage of rims with smoother finishes especially at the place where spokes are fixed
  • Usage of good rim tape to avoid damages to the tube by rim sharper points
  • Regular inspection of inflation pressure and tyre wear.

When a tyre should be replaced?

Following are the main parameters for the replacement of tyre

  • Complete worn out tread
  • Excessive sidewall cracks – Normally this happens earlier than tread wear as most of the times, the cycle is not used and or kept under lower inflation pressure
  • Damaged tyres with bad cuts and bruises where the chances of tube deflation is very high

What is a cycle tube?

A cycle tube is an elastic air container made of natural rubber (or blend of natural and synthetic rubber) or butyl rubber compound. It contains one way valve for letting air inside. The inflated tube is the real carrier of load of the rider and bike. Hence the maintaining of inflation pressure in tube is very critical.

Natural rubber based tube is stronger and hence more puncture resistant; however air retention is lesser compared to butyl tube.

Butyl tube has got higher air retention and heat resistant properties. Due to this butyl tubes can be made in significantly lighter compared to natural rubber.

Having said above, the compounding (also called as formulation or recipe) of the tube (whether it is natural or butyl) is a critical factor. A poorly compounded butyl can be worse than good natural rubber based compound.


 
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