External-bearing cranks, etc.

[Desertrider]

Having been a bit out of the loop on current bicycle component technology, I'm now researching what parts I want to install on my Thorn Nomad frame when it comes. Some I'll be switching over from my current bike, but I'm sure the new-parts bug will be infecting me as well.

I'm curious about the new splined cranksets with external bearings. At first glance the bearings seem pretty vulnerable, but RaceFace, for example, claims theirs are well-sealed. Certainly the purportedly stiffer nature of this type of crank would seem to be a good thing for touring. Does anyone have any experience with these, or are they strictly the purview of sport riders?

Also, in looking at the various levels of crank, the high-end models, sometimes a quarter-pound lighter than the base versions, are attractive. They seem to be aimed at "racers." The question is, is this "race" technology--light weight at no claimed loss of strength--applicable to us (assuming suitable chainrings will fit)? I'm not trying to build a 20-pound touring bike, but at the same time saving weight where possible is always a good thing.

Another topic: What about tubeless tires for touring?

Any comments or experience? Thanks . . .

[David Cox]

I needed a crank that was strong, stiff, had a robust spindle and cartridge bearings... so I went with this:
http://www.danscomp.com/cgi-bin/hazel.cgi?action=DETAIL&item=451057

Sure, it weighs a bit more than the typical touring crank, but I'm 6'6" 275 and wanted a crank that would hold up.  I really like how the crank feels and I don't notice the extra weight at all.  What I do notice is the stiffness and solid build.  Oh, and adjusting the chain-line is simple too.

[jgrgilbert]

One advantage of the external bearing cranks that is touted by the manufacturers is that the balls in the bearings can be larger, and should therefore last longer. But I don't believe they have been out for long enough to judge their reliability. The idea may be valid, and most manufacturers seem to be going for it, but there may be problems with specific models that we don't know about yet.

I would avoid the ISIS system. It seems to be unreliable due to the tiny ball bearings it uses. One of my friends has had problems with the ISIS bottom bracket on his Cannondale from new.

The Shimano UN53 bottom bracket has a reputation for super reliability. I have its predecessor on my road bike, and it has lasted 7 years so far. You would then have a huge choice of square taper cranks to go with it.

[Desertrider]

David, that is one serious crank!

And I've heard other reports about the small ISIS bearings.

Certainly a good point about the wide choice of cranks for standard BBs. But the claims of the external-bearing BBs and splined cranks to combine light weight with high strength are intriguing.

Anybody have experience with tubeless tires? Seems like a technology in its infancy still, and no doubt tire choice for serious touring is slim. But it's another promising development.