I've often heard the lamentations of too-big bolt circle diameters (more noticeably on the BOB list), but there's a reason for relatively large (maximal) BCD's.
Where the BCD is any smaller than necessary, the design of the whole crankset becomes less optimal: i.e. heavier, flexier (thus poorer, less predictable shifting under worst conditions) and likely noisier (as the freestanding rings resonate). This is why the best cranksets are designed around near-maximal BCD's for a given ring size, even when it limits the ability to gear down. The very same issues have lead better cassette designers to use riveted aluminum carriers.
Doubtless a smaller BCD version of the newest retro cranks would serve well for some, especially if/when the double version hits market. How much smaller can it be before the style is no longer reminiscent of the original? Does the current "road compact" diameter have legs (into the future), or will rear clusters continue to edge up in size and # of cogs (or both)?
David Snyder
Auburn, CA usa
> Hi Paul, all. I prefer shoulder pads to the perpetuation of the 144 bcd.
> Billy [just sayin'] Ketchum; Chicago, IL; USA.
> ----- Original Message -----
> From: "Dr. Paul B. Williams" <castell5@sympatico.ca>
> To: gillies@ece.ubc.ca, classicrendezvous@bikelist.org
> Sent: Tuesday, April 27, 2010 7:16:36 PM GMT -06:00 US/Canada Central
> Subject: Re: [CR] Sea Otter Retro
>
>
> Everything old is new again - one thing we can thank the "messenger" and
> "fixie" fad for! Those cranks look great - wonder if they will reproduce a
> double chainring version? Now, let's hope the current craze for 80s
> shoulderpads is short-lived!
>
> Paul Williams,
> Ottawa, ON, Canada