When we took over the distribution of SKF bottom brackets, we didn’t have high expectations for the ISIS bottom brackets. We were surprised when they became one of our more popular products. We sell them to customers who haven’t heard of Bicycle Quarterly, supple tires or any of the other things that we usually are associated with.
ISIS was an “open source” standard developed by a few of small makers – including Race Face and Truvativ – to counter Shimano’s proprietary Octalink interface. Shimano discontinued Octalink when the company began to attach the spindle to the right crankarm. Other companies followed suit, leaving ISIS as an orphaned standard.
ISIS made sense in theory, with a splined and tapered interface, but in practice, the large-diameter spindle left too little space for the bearings inside the standard BB shell. Most ISIS bottom brackets last only a few months in hard use.
SKF got around this problem by running the bearings directly on the spindle and shell, which allows the use of much larger bearings. The drive-side bearings are roller bearings, which have very high load ratings. In fact, the bearings of SKF’s ISIS bottom brackets are exactly the same as those of their indestructible square taper bottom brackets.
In an odd twist of fate, we ended up with the only reliable ISIS bottom bracket on the planet. Instead of replacing bottom brackets after just a few months of service, riders now can rest assured that our 10-year warranty on SKF bottom brackets includes the bearings. If you have a cherished ISIS crank, these bottom brackets allow you to extend its lifespan for at least another decade. Most likely, this will be the last ISIS bottom bracket you’ll ever have to buy.
I am almost tempted to offer the René Herse cranks with an ISIS splined interface, now that there are reliable ISIS bottom brackets…