Spoke length calculator: J-bend and straight pull

Spoke lengths

Left (non-drive, disc side)

291 mm

290.9 mm worked out

14 spokes, 3-cross

Right (drive side)

290 mm

289.7 mm worked out

14 spokes, 3-cross

J-bend spokes, 28 in all, on a 591 mm ERD rim. The big number is rounded to the nearest mm; most spokes come in 1 or 2 mm steps.

Please check before you order spokes.

These lengths come from the rim and hub makers' published sizes and a standard sum. Rims and hubs vary from batch to batch, and the sizes you put in yourself are only as good as your measuring. Measure your parts and check the result before you buy.

Travers Bikes takes no responsibility for spoke lengths worked out with this calculator, or for spokes, wheels or parts bought or built using them.

Rather not risk it? I build wheels here in Rochford and order the spokes for you.

Build a wheel with me See Nextie rims

How it works

It uses the standard spoke length sum: the rim's ERD, the hub's flange diameter and centre-to-flange size on each side, the number of spoke holes and how many times each spoke crosses. J-bend spokes lose a little to the bend at the head, so the calculator takes that off. Straight-pull spokes don't, so it doesn't.

Where the numbers come from

Rim ERDs are Nextie's own. Hub sizes come from Hope, DT Swiss, Chris King, SON and Nextie's published charts and drawings, and for Shimano from published wheel-building data, because Shimano don't give the sizes a spoke sum needs. SON hubs use SON's own figures, including the set lacing on the SON 29 S. Parts change and makers sometimes revise their numbers, so measure what you have in front of you if you can.

Want me to build it?

I hand-build wheels in Rochford with Nextie carbon rims and Hope, DT Swiss, Chris King, Shimano, Nextie and SON hubs. I work the spokes out and order them, so getting the length right is my job, not yours. Price a wheel build.

Spoke length questions

What is ERD?

Effective rim diameter: the diameter across the rim, measured to where the spoke ends sit inside the nipples. It's the number that matters most for spoke length. Rim makers list it, and every Nextie rim is already in the calculator.

What's the difference between J-bend and straight-pull spokes?

A J-bend spoke has a bend near the head and hooks through a hole in the hub flange. A straight-pull spoke has no bend and sits in a slot in the hub. The hub decides which you need. The calculator allows for the bend on J-bend spokes.

Why are the left and right spokes different lengths?

The flanges sit at different distances from the centre of the hub, to make room for the disc rotor or the cassette, and on some hubs the flanges are different sizes too. So each side needs its own length.

Should I round up or down?

Round to the nearest mm, or down if you're between two sizes. A spoke that's a touch short still gets a good grip in the nipple; one that's too long pokes through and can bottom out before the wheel is tight.

How many crosses should I use?

Three-cross suits 28, 32 and 36-hole wheels. 24-hole wheels usually go two-cross, and 20-hole or fewer two-cross or radial on the non-disc front side only. Disc sides and drive sides need crossed spokes to carry the twisting load.

How do I measure my own hub?

Flange diameter is across the centres of two opposite spoke holes. Centre to flange is from the middle of the hub, halfway between the locknuts or end caps, to the middle of each flange. Calipers make it much easier. If the hub maker publishes the numbers, use theirs.