Truvativ Ominum track cranks, external BB, 144 BCD. I like it!
http://www.sram.com/en/truvativ/specialtycranksets/
Note: ‘for the train spotters’, Spencer Street back drop in the webpage.
Hey they look pretty nice. The specs don’t mention the Q factor tho - I wonder if the outboard BB limits it… The ones on the website look better than the example photo 
What’s with the Spencer St image? ahah
Yes, Q-factor will be wider than a std. BB. Probably not so ideal for the track, but OK for the street.
emmachizzit?
If it’s the first outboard BB in the world wouldn’t they have made the cranks to compensate for the extra width of the matching BB (think Shitmano Saint)? Also having a much thicker spindle would enable you to have a laterally thinner arm at the arm/spindle interface yes?
I would think that a company like SRAM/Truvativ wouldn’t have made the same fuckup as Paul did with their original stuff.
On the trainspotting topic, isn’t that the chimney thats going to be pulled down? The one thats behind the left side of the crank front page…
Wouldn’t that just reduce the amount of thread for the pedals = not good?
And would a thinner arm introduce unwanted flex?
Des
Sorry BB spindle, not pedal spindle.
Nah Christof, The outboard BB gives better BB rigidity, which is largely unrelated to the crank arms. The crank arms of an outboard BB crankset are still as beefy (as a square taper/ octalink etc crank arm) to keep crank arm flex to a minimum as Des described.
The Q-factor on an outboard BB will generally always be slightly wider than other systems as there’s a limit to how much your spider can ‘envelop’ the BB. Watch this space though, they’re bound to get narrower in time…
Retail price from a US website is quoting $220.0 USD which is approx. 270.00 AUD (not sure if that includes BB)
Hmmm interweb confusion, I’m postponing this discussion for a more appropriate time.
Coz if they push it in any further, the heel of your shoe will be hitting the center of the spider when you pedal. To get the Q factor down, they’ll have to make the crank arm really thin but still ensure that the spindle/crank arm interface is strong and that the cranks arm itself is still stiff. The latter they can probably do by making the arm wider. Not so sure about the former.
Coz if they push it in any further, the heel of your shoe will be hitting the center of the spider when you pedal. To get the Q factor down, they’ll have to make the crank arm really thin but still ensure that the spindle/crank arm interface is strong and that the cranks arm itself is still stiff. The latter they can probably do by making the arm wider. Not so sure about the former.
[/quote]
Square taper is such a simple ,effective and more adjustable solution.
If that is the case, why does it seem that square taper stuff is not as accessible as the other designs?
Pick your reason:
-
Outboard BBs are stiffer than sqaure taper BBs. Most people can live with wider Q factor if the result is a stiffer drive.
-
Shimano who came up with the design controls a large share of the MTB market. What they say goes. Smaller guys like FSA, Raceface and Truvativ eventually had to switch to stay competitive. Eventually, the design trickled down to road bikes due to its popularity.
-
It’s cool to own something “high-tech” and modern even if the old design serves the purpose well. Carbon bikes ridden by non-racer types to the cafe are a case in point.
Des
Square taper isn’t as stiff as the external BB system, so the only factions interested in staying with it are track and touring cyclists, for Q-factor reasons.
As as aside - I find that External BB is more easily serviced that ‘in-frame’ BB’s.
(hmmm… Des beat me to it. Differently)
I like that a square taper means you can use the same cranks with different chainlines, by changing the spindle length.
Can you adjust chainline towards the frame with an outboard BB setup?
To a minor extent:
The BB spindle is a fixed length, but (in the case of Shimano), the crankset comes with a number of spacers that allow you to tune the chain-line to different BB shell widths.
Thus widening the Q-factor…
I suppose the solution would be to have a shorter, single-chainring length spindle (or maybe that already exists…)?
So that means you can only make the chainline wider, not narrower.
A short spindle version would be good I guess.
Anyway I don’t like all those modern fat Shimano cranks 
they’re probable significantly lighter as you can have hollow axles.