Skip to content

The diameter is stamped on your existing post — read it

Prophete Steel seatpost, 27.2 × 300 mm (1.07 × 11.8 in)

The cheapest item in this hub: a rigid steel seatpost in 27.2 mm diameter and 300 mm (11.8 in) length, for city, trekking and e-bikes.

Prophete black steel bicycle seatpost

Prophete Steel seatpost, 27.2 × 300 mm (1.07 × 11.8 in)

The cheapest item in this hub: a rigid steel seatpost in 27.2 mm diameter and 300 mm (11.8 in) length, for city, trekking and e-bikes.

Diameter
27.2 mm (1.07 in)
Length
300 mm (11.8 in)
Material
Steel, unsprung
Use
City, trekking, e-bike
Amazon reference
B08259V2GD (identical on 6 markets)
EAN
4009208065060
  • The most common seatpost diameter, so it fits a very large number of frames
  • Steel, which is heavier than alloy and considerably tougher
  • One diameter only — 27.2 mm (1.07 in) and nothing else

Best for: Replacing a damaged or too-short seatpost on a city or trekking bike.

≈ $30
Check price on Amazon

Specifications

Diameter
27.2 mm (1.07 in)
Length
300 mm (11.8 in)
Material
Steel, unsprung
Use
City, trekking, e-bike
Amazon reference
B08259V2GD (identical on 6 markets)
EAN
4009208065060

A seatpost is a single measurement, and this is the most common one.

What the manufacturer publishes

A stable steel tube: a robust, unsprung steel seatpost with high load capacity. Standard dimensions of Ø 27.2 mm (1.07 in) and 300 mm (11.8 in) length, suiting many bicycles. Universal use with a classic black design, usable on city, trekking and e-bikes. Simple mounting, suitable for common seat clamps.

Reading the diameter rather than measuring it

The common sizes are 25.4, 27.2, 30.9 and 31.6 mm (1.24 in). The steps between them are fractions of a millimeter, which no ruler resolves reliably and which no amount of force overcomes.

The number is printed on the post currently in your frame, usually just above the minimum insertion line. Pull the post far enough out to read it.

The line that is not negotiable

Every seatpost carries a minimum insertion mark. The post must sit below that line inside the frame. It is the manufacturer’s statement about where the post is strong enough to be clamped, and riding above it risks both the post and the frame.

If the saddle cannot reach the right height with the mark buried, buy a longer post — do not raise this one further.

Tightening the clamp

To the torque figure printed on the clamp. Over-tightened seat clamps crack frames; under-tightened ones let the saddle slip mid-ride.

The questions riders ask

How do I know my diameter?

Read it off the post already in the frame — it is printed or etched near the minimum insertion mark. Do not measure with a ruler: the steps between 27.2, 30.9 and 31.6 mm (1.24 in) are under a millimeter and a tape measure will not resolve them.

Is 300 mm (11.8 in) long enough?

For most riders on a correctly sized frame, yes. A tall rider on a small frame may need 350 or 400 mm (15.7 in) — the minimum insertion mark must stay below the frame's clamp, without exception.

More saddles and seatposts

  • Air Seat sprung saddle suspension mounted under a bicycle saddle

    Air Seat Air Seat sprung saddle suspension

    The premium option here: a patented sprung saddle suspension designed to move in all directions rather than only vertically.

    Design
    Patented, moves in all directions
    Versions
    Matched to rider and riding style
    Compatibility
    Stated for e-bikes and conventional bikes
    Amazon reference
    B0DFCSG6FH (identical on 5 markets)
    EAN
    4270004242218
    • Movement in all directions rather than only vertical, which a telescopic post cannot do
    • Versions matched to rider weight and riding style rather than one size
    • Not listed on the US market

    Best for: Riders who have tried a telescopic suspension post and still find the ride harsh.

    Search Amazon for this model
  • LAINFELD suspension seatpost showing its spring mechanism

    LAINFELD Suspension seatpost, 27.2/30.9/31.6 mm (0.24 in)

    A 350 mm (13.8 in) suspension seatpost in three diameters, with adjustable spring rate and seat angle and the tools supplied.

    Diameters
    27.2, 30.9 and 31.6 mm (1.24 in)
    Length
    350 mm (13.8 in)
    Spring
    Adjustable rate
    Seat angle
    Adjustable
    Included
    2 hex keys
    Amazon reference
    B0DWQ52RN8 (identical on 6 markets)
    EAN
    4262384331064
    • Available in the three most common diameters, so it fits most frames
    • An adjustable spring rate, which is what makes a suspension post work for your weight
    • A suspension post changes saddle height under load — set it with your weight on the bike

    Best for: A commuter or e-bike on poor road surfaces, where the seatpost is the cheapest suspension available.

    Check price on Amazon

Elsewhere in the spares drawer

  • Orange Seal Endurance tubeless sealant 8 oz bottle with injector

    Orange Seal Endurance 237 ml + injector

    A 237 ml bottle of latex Endurance sealant with an injector, sealing punctures to 6.35 mm (0.25 in) and slices to 12.7 mm (0.50 in).

    Volume
    8 oz (237 ml)
    Injector
    Included — capacity not published
    Price per ml
    8.2 cents, against 4.9 for the 473 ml refill
    Base
    Latex with nanite particles
    Seals punctures to
    1/4" (6.35 mm (0.25 in))
    Seals slices to
    1/2" (12.7 mm (0.50 in))
    Service interval
    60–120 days
    Weight
    227 g (8 oz)
    Casing
    No delamination or rubber damage, stated
    Particle size
    Not published
    Temperature range
    Not published
    CO2
    Not addressed
    Amazon reference
    B07YF3JQF8
    EAN
    0810026608100
    • The only item here that supplies both sealant and injector
    • Publishes both a hole figure and a slice figure, alone on this shelf
    • 8.2 cents a milliliter against 4.9 for the same sealant in 473 ml

    Best for: A first tubeless setup, with the 473 ml refill bought next time

    Check price on Amazon
  • Schwalbe Doc Blue Professional tubeless sealant bottle, 200 ml

    Schwalbe Doc Blue Professional, 200 ml

    A 200 ml bottle of Schwalbe's Doc Blue Professional sealant, sized for preventive use and for tubeless conversion on Schwalbe tires.

    Volume
    200 ml
    Use
    Preventive and tubeless conversion
    Description
    Environmentally friendly, seals small holes and punctures
    Amazon reference
    B0BRKYK322 (identical on 6 markets)
    EAN
    4026495896139
    • Rank 1,224, and the cheapest way into tubeless sealant here
    • A 200 ml bottle, which is roughly one to two wheels depending on tire size
    • Two hundred milliliters does not go far on wide tires

    Best for: A first tubeless setup, or topping up an existing one on road or gravel tires.

    ≈ $73
    Check price on Amazon
  • SILCA Ultimate tubeless bike tire sealant one liter bottle

    SILCA Ultimate sealant, 1,000 ml, FiberFoam

    A liter of hybrid latex sealant with carbon fiber FiberFoam, sealing punctures up to 7.5 mm (0.30 in) and staying liquid beyond six months.

    Volume
    1,000 ml
    Price per ml
    4.5 cents — the cheapest sealant here
    Base
    Hybrid latex
    Sealing agent
    FiberFoam carbon fibers, "400% stiffer than fiberglass"
    Seals punctures to
    7.5 mm (0.30 in)
    Service interval
    6+ months, weather dependent
    Temperature
    Down to −15 °C (10 °F)
    CO2
    Safe
    Injector
    Sold separately — SILCA’s own holds 59 ml
    Slice figure
    Not published
    Volume per wheel
    Not published
    Latex-free
    No
    Amazon reference
    B0DX2F3V5Q
    EAN
    0810093162901
    • The largest published hole figure on this shelf, 7.5 mm (0.30 in)
    • Six months between top-ups, double the Orange Seal interval
    • No slice figure, where Orange Seal publishes 12.7 mm (0.50 in)

    Best for: A tubeless rider who tops up twice a year and inflates with CO2

    Check price on Amazon

All saddles and seatposts