In 1984 MAVIC updated its MAVIC 800 derailleur, and spawned two new models the MAVIC 801 and the MAVIC 851. The two models were virtually identical, except in one crucial regard - the 801 was largely silver, but the 851 had dark, hard-anodised, parallelogram plates and a coach line on its pulley cage. This gave the 851 a brooding, rebellious look that matched perfectly with the, then ultra-desirable, also hard-anodised, macho MAVIC SSC rims. A star was born.

It would be churlish to suggest that a touch of hard anodising and the odd coach line might have meant that the production cost of the 851 was perhaps all of one French Franc higher than that of the 801. But that did not stop the 851 from living up to its 'ultimate' billing by costing the bedazzled consumer substantially more than the plain vanilla 801. Style is almost always more valuable than content. If the Three Kings turned up in Bethlehem today they would be bearing gold, frankincense and a gift voucher for the services of a personal stylist.

I know of four variants of each of these derailleurs:

• The first (1984?) version was very similar to the last variant of the MAVIC 800 - but with a new adjustable black cage. You could slide this cage at the p-pivot to optimise the chain gap. You could also adjust the rotation stop to give more or less pulley cage rotation.
• The second (1985?) version dispensed with the recessed logo and had a flat outer parallelogram plate with either an engraved log (on the 801) or a painted logo (on the 851). I am a little unclear about the pulleys on this generation. My 801 has cup and cone bearings, but my 851 has sealed bearings. It is possible MAVIC moved both models onto sealed bearings at some point in 1985.
• For the third (1986?) version both the 801 and the 851 had painted logos. They benefitted from a redesigned p-knuckle with the pulley cage rotation stop butting up against the knuckle (rather than a bolt head). This generation had sealed bearing pulleys which were mounted between two thick silver aluminium washers.
• The fourth (1988?) versions of both the 801 and the 851 were identical to the third versions - except that they had a new design of sealed bearing pulley wheel which did not require the two thick silver aluminium washers.

This may be a slightly abridged history - I have also seen an 801 where the large allen bolt at the p-pivot has a female, rather than a male, thread. These are 'artisan' products, and any batch may vary in any way at any time.

Afficionados love these derailleurs. Part of this may be because they were favoured by legendary cyclists - Sean Kelly was a fan of the MAVIC 851 and Greg Lemond won the 1989 Tour using one. Since 1946, the MAVIC 851 is the only Tour winning derailleur that was not from one of the major, million-selling, brands of the time: Huret, Simplex, Shimano, SRAM or Campagnolo.

But part of this love is also because of the overall industrial design of these beauties. Here I have to differ. The adjustable cage is fiddly, arguably useless - as nearly all these derailleurs ran over close ratio frewheels, and the strange flanged clamp nut frequently cracked. The black pulley cage plates, the painted logos and, on the 851, the hard anodised paralelogram plates all became scratched. And finally the pulley cage plates had lost their pure geometrical form. Playing the role of curmudgeonly baby-boomer, I much prefer the MAVIC 800.

Finally I should note that MAVIC sometimes calls the 801 the 'MAVIC 801 Pro' and the 851 is sometimes called the 'MAVIC 851 SSC'. 'SSC' stands for 'Special Service Course' and references MAVIC's status as provider of the neutral service vehicles at major races. It implies that components bearing this name are for the very toughest professionals riding the very toughest races - think Sean Kelly riding Paris-Roubaix. These extravagant names tended to appear in the derailleurs' later years and seem to be especially prevalent in materials for the US market. In earlier years labels like 'SSC' seemed to be reserved for rims and groupsets.

---

I think that this is a, rather beautiful, example of a later MAVIC 851, mainly because the pulley cage rotation stop engages with a flange that is part of the p-knuckle. Some of its key features may be:

• The logo is painted on the outer parallelogram plate.
• The parallelogram plates are hard anodised.
• There is a stainless steel plate at the b-pivot that engages with a Campagnolo end.
• The pulley cage is black with a white coach line and is adjustable.
• The pulley wheels have sealed bearing races, but they have a central core that does not require the previous two thick silver aluminium washers.
• The pulley cage rotation stop engages with a flange that is part of the p-knuckle.

Note that these later MAVIC 851s have a claimed maximum sprocket size of 30 teeth - earlier versions were supposed to handle 32 teeth. Personally I would have worried about anything over 28 teeth for any of them - but that's me.

---

• Derailleur brands: MAVIC
• Themes: Ultra-lightweight - short cage models
• Country: France
• Date of introduction: 1988?
• Date of this example: April 1988 (the p-knuckle is stamped '8804E')
• Model no.: 851
• Weight: 172g
• Maximum cog: 30 teeth (source: MAVIC)
• Total capacity: unknown
• Pulley centre to centre: 45mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: unsprung
• P pivot: sprung
• Materials: largely aluminium