I posted this to the BOB list this morning, but thought CR people might be even keener at spotting the differences or similarities between the on- and off-topic TA cranks.
Here is my question:
I have in my possession one of the newer TA Pro 5 vis cranksets -- produced in 2007. I also have a TA Axix BB, which is from the same year. The BB is 116mm wide, which I have always heard is the correct width for TA doubles. This BB is completely symmetric.
I ran this setup on Fuji touring bike for a few months last year to test it out, and everything seemed in order. There wasn't much crankarm clearance on either chainstay (I was using a 135mm rear end and fairly beefy chainstays), but things seemed more or less centred.
I was testing it for the still-forthcoming custom frame I expect to arrive in a few months. In the meantime I've become interested in this question of symmetricalness. For it seems TA's older bottom brackets for Pro 5 Vis doubles were not symmetrical.
Piece of evidence number one: this chart from Sheldon Brown's website:
http://www.sheldonbrown.com/
This suggests that the BB should be offset VERY slightly (1.5mm) toward the drive side.
And this photo of a TA 344 axle (the very one specified for TA doubles in the above diagram) seems to show an even more significant driveside offset, though it is the same length as my symmetrical Axix BB: 116mm. (It may be .5 longer...)
http://picasaweb.google.ca/
My question basically is: did TA change their cranks for the newer production runs to make them work with symmetrical BBs when they used to be designed for asymmetrical? If I were to have mounted my TA cranks onto the aforementioned Fuji touring bike with one of the TA 344 axles, I would have had one crankarm 8mm out from the chainstay, and the other smacking straight into it.
To throw a final crankarm into the spokes: I have heard various rumours that the new TA production is designed for JIS spindles (and that the Axix BBs use JIS spindles) -- would this explain all the confusion?
Confused,
Adam