Balfa BB7 frame overview
Table of contents:
The Balfa BB7 is a 9-inch-travel, single pivot, downhill frame. Hand made in Montreal, Canada between 1999 and 2005 (see "Model history" for details). What distinguishes it from other frames is its unique design ideas described below.
The pivot point was originally placed 7" (about 178mm) above the bottom bracket (now you know why it's called a "BB7"). In later models this distance was increased up to 9" (228mm).
While most frame manufacturers place the pivot point according to the chain, Balfa placed the chain according to the optimal pivot location. This is done by a pulley routing the chain close to the main pivot to avoid chain tension problems. The rear triangle is then fully active and independent in its travel, giving freedom of movement unequaled to this day. This unusual chain line permits the application of the true high pivot and allows for a better rear end with ample travel and no feedback.
A high pivot point also makes it possible to achieve a rear axle path nearly parallel to the movement of front wheel.
Some other bikes that use high pivot suspension design:
- Appalache Real
- Trek Session 10
- BMW (Brooklyn Machine Works) Race Link and SR-6
- Dark Cycles Scarab DH
- Empire Cycles AP-1
- Superco Silencer
When your rear wheel catches an impact, the location of the pivot (higher than the centre of the rear hub) will push the wheel up, of course, but also rearward. The trajectory of the rear wheel is then more similar to the trajectory of the front wheel, giving stability, therefore maximizing steering precision.
The parallel trajectory allows to maintain speed through big impact sections. Unlike the typical wheel trajectory where the wheelbase will increase in the beginning and decrease in the end of the travel, the rear will work in the same direction as the front, keeping the wheelbase intact and a wheel path that doesn't interfere with the laws of gravity.
For more info about high pivot, rear axle patch and other, visit Suspension design page.
BB7's swingarm is made of steel, instead of traditional aluminum (of which front end is made). Benefits are:
- Increased tire clearance (to obtain the same rigidity, the aluminium tube will have to be much bigger in diameter than its steel counterpart) - it's the main reason;
- Longer lifespan (steel is less prone to fatigue over time);
- Easy to repair (steel is much easier to weld or straighten);
- Derailleur hanger will bend, rather than break off (like in aluminum frames) and you will be able to realign it many times before it breaks;
- Steel can absorb vibrations (eg. from chain slap) better, which makes for quieter ride
BALFA is a Cajun family name that apparently evolved from the English "Balfour" over the centuries. The Cajun culture, hybrid between the French and English cultures, is very rich and most interesting. Frederic and Jerome, the two BALFA Cycles founders were looking for a name that would express the complexity of their French origins in an English speaking continent. They both have a passion for history, music of all kinds and culture, and through their research, the name BALFA came up.
This article is based on official Balfa Cycles FAQ.