Re: [CR]Curved Cottered Cranks?

(Example: Racing:Wayne Stetina)

Date: Wed, 28 Mar 2007 08:54:06 -0600
To: Festiva 90 LX <festiva90lx@yahoo.com>
From: "Mark Stonich" <mark@bikesmithdesign.com>
Subject: Re: [CR]Curved Cottered Cranks?
In-Reply-To: <825106.56958.qm@web54402.mail.yahoo.com>
References: <825106.56958.qm@web54402.mail.yahoo.com>
cc: classicrendezvous@bikelist.org

At 3/27/2007 05:26 PM -0700, Festiva 90 LX wrote:
>Were there ever any curved cottered cranks? I need a curved left
>crank to provide clearance for an ankle brace, and I do not want to
>convert to cotterless.
>
>David Lester
>West Hartford, Ct. USA

David just contacted me about this with additional info not mentioned in his CR posting.

David, To get the ankle clearance you want, you have two options, bending the cranks or Knee Savers. Neither option is appropriate with the the aluminum Maxiplume cottered aluminum cranks on your Chemineau, which I assume is french threaded.

I've heard you could retap the crank to English threads, but don't know how sound the resulting threads would be. Or, the same machinists who worked on your cotter press and fixed cup tool were making knee savers long before "Knee Savers" appeared on the market. For an appropriate fee, they could make you some lefts with French threads.

If you went to a steel cottered crank, that could be bent.

BTW This sort of a bend should definitely be done cold. I've had to learn a lot about the bending of metals, and the pros rarely use heat to bend metal less than several inches thick. Blacksmithing is for when you need to drastically alter the shape.

I just went downstairs and put about a 3/4" offset in a Solida, French threaded, left crank arm, using a VAR crank straightener and a big vice. It would take me a while to fine tune the alignment, because my alignment tooling is English threaded, but if you are interested contact me off list. Condition is; a few rust spots and minor nicks, probably appropriate to the bike. .

I don't have the matching right arm. So if it will help, you can have it for postage and something for the time I'd put into aligning it.

In an earlier posting you had mentioned wanting to stay with your TA Cyclotouriste chainrings. There were were steel cottered cranks that used the same 2" (50.8mm) 5 pin BCD and french threading. Hope you can find one. I used to have several, but back in the '70s I cut various amounts out of them and welded the left eyes on the right arms and vise versa to make tandem Kiddie Kranks.

Mark Stonich;
Minneapolis Minnesota
http://mnhpva.org
http://bikesmithdesign.com