Choosing JOMA Segments, Sizes & Flex

Segment length follows the moldboard; flex follows the surface

Two decisions settle most JOMA-style specifications: how long each segment should be, and how much flex the route needs. This page covers both, plus the handling and cost consequences of each choice.

✓ 3ft, 4ft and custom segment lengths
✓ Flex, rubber hardness and surface compliance
✓ Handling, weight and cost consequences

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Segment length is a handling decision as much as a technical one

Shorter segments follow broken surfaces more closely and are easier to fit alone. Longer segments are cheaper per metre and need two people.

Three-foot, four-foot and custom

The standard lengths exist because they balance surface compliance against cost and handling. A four-foot segment on a wide moldboard reduces the number of joints; a three-foot segment follows a rougher surface and lets you replace less material when one section is damaged.

What the moldboard dictates

Overall width, mounting-hole spacing and the position of the outer ends decide which segment lengths can be used at all. Bolting a flexible edge with mismatched segment lengths creates stiff points along the edge, which is where cracks and wear concentrate.

Flex should match the surface, not be maximised

More flex is not better. It is right when the road is crowned, cracked or patched, and wrong when the surface is flat and the problem is ice.

Reading the surface

Crowned roads, patched asphalt and driveways with transitions between surfaces reward a flexible edge because it keeps contact without extra down-pressure. Flat, sound pavement gives the flex nothing to do, and the softer body simply wears faster.

Rubber hardness and cold behaviour

Rubber stiffens as it cools, so a compound chosen for a mild climate behaves differently below -30°C. In deep cold the edge needs to stay flexible enough to follow the road and keep its bond to the carbide inserts intact.

Segment selection questions

Should I choose 3ft or 4ft segments?

Choose from the moldboard width and the surface. Rougher or more crowned surfaces favour shorter segments; wide, reasonably sound surfaces favour longer ones for cost and fewer joints.

Does more flexible always mean better?

No. Flex earns its keep on uneven surfaces and costs wear life on flat ones. Match it to the road rather than maximising it.

Will flexible segments work in extreme cold?

Yes, provided the rubber compound is selected for it. Rubber stiffens as it cools, so a mild-climate compound behaves differently at -30°C.

Can I mix segment lengths on one blade?

Usually yes, and it is common at the outer ends. Keep the joints away from the highest-load area and check that the mounting pattern supports each section.

How many spare segments should we hold?

Enough to replace the damage rate of your busiest route, plus one spare of each length in use. Section-level replacement is the main advantage, so use it.