How to Choose a Rear Hub: Flange Width, Dish, and What the Spec Sheet Hides

The one dimension that decides a rear wheel's lateral stiffness — and how to read it off a catalog that's trying to hide it. With links to the original posts.

Riders choose a rear hub on bearings, freehub engagement, and weight. Those matter — but the dimensions that decide how the finished wheel rides barely make the marketing copy, and one manufacturer's spec sheet is arguably built to obscure the most important one. Here's how one workshop reads a rear hub, with the source links. "Right" means the drive (freehub) side; "left" the non-drive side.

1. The numbers that matter

Three hub dimensions feed both the spoke-length calculation and the wheel's lateral stiffness: flange width (outer face to outer face), flange diameter, and the resulting dish — how far off-centre the two flanges sit. Bearings and freehubs you can service or swap; flange geometry is baked into the hub forever, so it's the thing to get right at purchase.

Source: Nomu Lab #227 — On wheel dish

2. Judge by left-flange protrusion

The instinct is to compare headline flange width. The better measure is how far the left flange protrudes from the centre. A rear wheel's lateral stiffness lives on the non-drive side, and that side is strong only if its flange sits far enough out. Two hubs with the same flange width can build very differently if one keeps its left flange wide and the other doesn't.

Source: Nomu Lab #227

3. Decoding the spec sheet

To compare hubs you need the left and right flange-to-centre distances (call them L and R). Some catalogs print them. Shimano, since 2012, prints flange width and a "dish amount" that is actually (L − R) / 2 — half the real dish. Recover the numbers like this:

• half = flange width ÷ 2
• L = half + (catalog dish)
• R = half − (catalog dish)

For an FH-6700 (flange width 59.2 mm, catalog dish 8.9 mm): half = 29.6, so L = 38.5 mm and R = 20.7 mm. Now you can actually compare it to another hub.

Source: Nomu Lab #227

4. Is more dish bad? Not necessarily

Dish gets a bad name because it drives the left/right tension imbalance. But dish on its own isn't the enemy. If the right flange sits in the same place, more dish means the left flange is farther out — a wider total flange, which is more lateral stiffness, not less. The workshop's general preference is for rear hubs with a large dish, precisely because it usually means a well-protruding left flange. Tension imbalance can be clawed back by lacing and gauge; a narrow flange can't.

Source: Nomu Lab #227

5. The spec-sheet trap

Source: Nomu Lab #227

6. Hi-lo flanges

A hub with a taller drive-side flange (a hi-lo flange) brings the left and right spoke incidence angles closer together, which eases the left/right tension imbalance without narrowing anything. Campagnolo was building hubs this way decades ago. It's a genuine plus on a rear hub — and unlike spec-sheet dish games, it doesn't cost you lateral stiffness. For why the angle matters, see the spoke tension guide.

Source: Nomu Lab #46