Bridgestone is an enormous multinational company, one of the largest tire companies in the world…and a fairly small bicycle company, with its own factory in Japan. In the late 1980s and early’90s, its U.S. bicycle division was run by Grant Petersen, a brilliant, talented and idiosyncratic designer.
Petersen, a hard-core cyclist, marched to a “different drummer” than most of the industry. He introduced many innovations to the market, and also strongly resisted other trends and innovations that he didn’t approve of.

Bridgestones have a backwards numbering system, and, generally, the lower the number, the higher the quality.

Road Models RB-1, RB-2, RB-3, RB-T

Bridgestone “road” bikes, particularly the legendary RB-1, combine frame design taken from classic Italian road bikes of the ’70’s with excellent Japanese workmanship and functional, reliable parts. The RB-1 was extremely popular with racers, and held its own against competing models costing hundreds of dollars more.
The RB-2 had the same geometry as the RB-1, but with slightly less expensive tubing and considerably less expensive parts.

The RB-3 was a low-end model, of little interest.

The RB-T was a touring bike introduced in the early ’90s, a time when touring bikes were extremely out of fashion with manufacturers. It was a very nice bike, but had trouble competing with the left-over stock of mid-80s touring bikes still in the pipeline. This bike also came with Avocet slick tires, which are splendid tires, but difficult to sell, since most people assume (incorrectly) that they will provide poor traction.

Mountain Bikes MB-1…MB-6

Bridgestone was one of the first companies to jump on the mountain bike bandwagon in the 1980s, but from a “road” perspective. Early versions of the MB-1 came with drop handlebars and 126 mm dropout spacing!
The predominant style of mountain bikes in the early-mid ’80s was the “California cruiser” geometry inspired by the Schwinn Excelsior “klunkers”, with 44 inch wheel bases, 18 inch or longer chain stays, and frame angles in the high 60 degree range. These bikes were very stable for downhill use on Repack hill, but were not very good climbers. Petersen’s Bridgestones had much steeper frame angles and much shorter chain stays, which made them considerably more maneuverable and nimble than the older designs, and considerably better climbers. In the ’80s this design was considered “radical” but it proved itself on the trail, and was copied by everybody a few years later. This Bridgestone design still is the standard for rigid-frame MTBs.

Some MBs were made in Japan, others in Taiwan, different models in different years. You can easily tell which, because the Japanese models all used lug construction, while the Taiwanese models were T.I.G. welded.

In the early ’90s, the Taiwanese MB-0 (a.k.a. “MB-Zip”) pushed the envelope of lightness for steel-framed mountain bikes. These top-of-the line bikes were amazingly light, but, unfortunately, a bit too light, and prone to frame failure if ridden hard off-road.

The XO Series

The “XO” series were the most idiosyncratic of Petersen’s designs. They were intended as fast, sporty urban street machines, primarily for pavement use, but more rugged than traditional “road” bikes. Most of them featured “moustache ” handlebars and slick medium-width tires.
The top-of-the-line XO-1 and other upper-end models used 559 mm (26 inch) tires, and 23.8 mm (15/16″) handlebars that used “road” type brake levers and bar-end shifters.

These bikes, especially the XO-1, are highly sought-after “cult” bikes today. The XO-5 was more like a typical “hybrid” with 622 mm (700c) wheels and a variant moustache handlebar with 22.2 mm (7/8″) diameter, that used “mountain bike” type controls. This model was rather too compromised. That version of the moustache handlebar had fairly poor ergonomics with the supplied controls.

The CB-1…CB-3
There was constant tension between Bridgestone USA and the parent company in Japan. While the bosses realized that Petersen was a very talented designer, he was perhaps a bit too individualistic and eccentric for the corporate culture. There were forces in Japan that wanted to make a more mainstream bike, like everybody else. In the give and take between the divisions, some models went one way, others the other way. The CB-series (City Bike) was intended as a bike for the non-enthusiast. There was nothing wrong with them, but nothing special, either. These were all Taiwanese models.
The most interesting of them was the CB-0.

Rivendell
After Bridgestone Japan pulled the plug on Bridgestone USA in 1994, Grant Petersen went on to found Rivendell Bicycles . As master of his own domain, he has since been free to march to his own drummer, producing Rivendell, Rambouillet , Atlantis , Romulus, Saluki, Betty Foy and other bikes with his special design flavor.
The Rambouillet and Romulus are reminiscent of the RB-1, or what the RB-1 might have been if Petersen had been given a free hand, and if 57 mm reach brake calipers had been available in the early ’90s.

The Atlantis may be seen as the lineal descendant of the XO-1.