Mavic uses the same front hub for four of their present and previous pair of hubs, the 501 & 571 road hubsets also the previous 531 mountain hubs, and the discontinued 577, mountain cassette hubset. Because the front hubs of all bikes use a 100mm over lock nut axle dimension this is a practical way to cut down on the number of different hubs that would have to be made. The hub shell is made of aluminum alloy then polished to remove the marks of the lathe work in making the hub round. Mavic uses precision sealed bearing cartridges that are held in place by machined aluminum lock rings. These lock rings are drilled to let the axle pass through and have six equally spaced 2.5mm holes bored in its face for a pin spanner to grip. The axle is machined from 15mm diameter aluminum rod, that is reduced to 12mm as it passes through the bearings. The 12mm diameter axle is threaded at the destination bearing, (the second bearing in contact with the axle), for a steel locknut that holds the axle in place between the two bearings. Both ends of the axle are also turned on a lathe to reduce them to the 9mm outer diameter standard used in fork ends. The aluminum axle has a groove cut 5mm from each axle end. A steel axle contact cap butts against the shoulder where the axle diameter steps up from 9mm to 12mm. The steel cap has a serrated outer face that presses against the fork end. The cap is held in place around the 9mm diameter area of the axle by compressing cir-clip. The exposed end of the steel cap grips the fork blade when compressed by the skewer. A rubber O-ring recessed around the steel locknut seals the bearing against outside contaminants. This hub is remarkably smooth in use.
The Mavic 501 road hubset has a threaded rear hub for use with a freewheel. The rear axle is 130mm long to accommodate 8 speed freewheels, or a steel end nut in the axle can be removed using a 5mm hex wrench and a 3mm aluminum spacer may be removed to reduce the axle length to just 127mm for use with 6 or 7 speed freewheels. The hub shell is made of aluminum, and polished to remove the marks from the lathe work performed to make it perfectly round. The rear hub uses two sealed bearing cartridges for load bearing. The drive side bearing is pressed into the bearing cavity directly. The non-drive side bearing is pressed into its cavity and an externally threaded lock ring is threaded in behind it to hold it in place. The lock ring has six 2.5mm diameter holes bored into its face for pin spanner installation/removal. The rear axle is machined from 14.8mm diameter 2030 aluminum alloy rod. The axle diameter is reduced to 12mm as it passes through the drive side bearing, leaving the shoulder from the 12mm to 14.8mm transition butted against the bearing. The 12mm diameter is threaded on the non-drive side for a steel lock nut. This lock nut, like the one used on the front, (in fact they're the same), has a rubber O-ring recessed in its interior. The lock nut is gripped with a 15mm cone wrench. A groove is cut around the non-drive axle end for a cir-clip seating of the steel end cap that will press against the drop-outs. The drive side, again has a steel end nut which threads into the axle. It's removable with a 5mm hex wrench to shorten the axle, this rear hub will accommodate a 6, 7, or 8 speed geared freewheel. The front hub is as described above. The label area of both hubs has a Grey rubber 501 label. A pair of chrome plated steel quick release skewers come with the hubset. The skewers use an internal cam design that constricts to close and lock the hubs onto the bike. The adjusting nut has two flat areas for the thumb and forefinger to grip as the skewer is tightened. The hubs are Silver (clear) anodized. The front hub has a 49.5mm hub flange diameter, with flanges spaced 55mm apart. The front spoke holes have a 40mm center circle diameter. The rear hub has a 54.5mm hub flange diameter, with flanges spaced 47mm apart. The rear spoke holes have a 46mm center circle diameter. With skewer, the front weighs 244.5 grams, (skewer is 83 grams), the rear with skewer, and without cogs, weighs 296 grams, (skewer 87 grams). The hubs are available in either 28, 32 or 36 hole drilling, matched the way you want. The rear is threaded for English thread freewheels only. The 501 front hub only sold for $79.99 The 501 rear hub only sold for $84.99, with the 501 hubset (pair) selling for $164.99
This 531 hubs is a variation on the 501 hubs described above. The hub shell, bearings, internal lock ring and steel lock nut are the same as the 501. In fact, its just minor differences in the axle, making it 135mm long for mountain bikes, and the rear skewer is slightly longer. The rear will accommodate an 8 speed freewheel used on any mountain bike. The hubs have a Green rubber label noting the 531 distinction. The hubs are Silver (clear) anodized. The front hub has a 49.5mm hub flange diameter, with flanges spaced 55mm apart. The front spoke holes have a 40mm center circle diameter. The rear hub has a 54.5mm hub flange diameter, with flanges spaced 47mm apart. The rear spoke holes have a 46mm center circle diameter. With skewer, the front weighs 244.5 grams, (skewer is 83 grams), the rear with skewer, and without cogs, weighs 298.5 grams, (skewer 88 grams). The hubs are available in either 28, 32 or 36 hole drilling, matched the way you want. The rear is threaded for English thread freewheels only. Now discontinued, the 531 front hub only sold for $79.99 The 531 rear hub only sold for $84.99, and the 531 hubset (pair) sold for $164.99