Re: [CR] Exploding SunTour Freewheels; was: Cinelli B lore


Example: Component Manufacturers

From: pcb@skywebusa.net
To: classicrendezvous@bikelist.org
Date: Fri, 14 Jan 2011 22:14:50 -0500
Subject: Re: [CR] Exploding SunTour Freewheels; was: Cinelli B lore


SunTour did introduce a tandem-specific freewheel with beefier pawls, I think it was a Perfect model, might have had a "T" for "Tandem" stamped on it?

Tandems put a remarkable strain on freewheels. We were having a back-and-forth with SunTour Japan on the Winner/Winner Pro pawl design, we thought the pawls were too weak and had heard of pawl breakage in the field. Japan had never managed to break one, and they claimed it was tested in Paris Roubaix and was the only freewheel that lasted the race. I sent some freewheels to a dealer in Maine who had an ATB tandem, who claimed he could break just about any freewheel at will. He broke a couple for me on one ride, and we broke a couple more with a bench vise and long breaker bar, then we sent Japan some busted freewheels. They changed the pawls from single-pawl engagement to dual-pawl engagement, which lowered pawl seat stress and fixed the problem. It wasn't unusual for insufficiently-tested product to ship before we had a chance to evaluate it, and we wasted gobs of time fixing messes like this.

Pawl breakage was much more common with large-ratio freewheels, we never saw one from a sub-26t ratio. It was all about leverage, not leg strength. Lots of chain wrapped around a big cog in a low gear puts a lot more stress than sprinting for the finish in a 53/12. Japan couldn't afford to throw out the bodies with weaker pawls, so they built them into close-ratio freewheels and shipped them out.

If you're looking at Winner/Winner Pro fws, and if you want the stronger pawl design, turn the freewheel one revolution and count the clicks. The weaker single-pawl engagement fws get something like 14-15 clicks in one revolution. The stronger dual-pawl engagement fws get only 7-8 clicks per revolution.

Paul Brodek Hillsdale, NJ USA

Quoting "Dr. Paddle" <drpaddle@yahoo.com>:
>
>
>
>
>
> As well as being apalling, those SunTour freewheels were depawling. I
> had one on
> my '50s Follis tandem, upgraded to a mix of mid-'70s touring gear,
> for a ride in
> about '75. We rode to Border Park, along the Mexican border in southern San
> Diego County. My comely stoker and I were the last of the group to leave the
> isolated park. As we rolled off, we found the freewheel fouly
> flipping forward
> (take that, alliteration man!). No fall, but stuck miles from a phone, miles
> from a shop, and dropped from the group. "Hah!" laughed I in the face of
> adversity. Pulling a pair of needle-nose from a subsaddle bag, I bent and
> worried three or four pieces of lashing from the barbly-wire border fence --
> the only international divider at the time -- then used them to bind
> the large
> freewheel cog to the spokes. We rode out gently on a fixed gear.
>  
> Kevin Montgomery
> San Diego, California USA
> Where such a fix would no longer be possible along the towering steel
> fences and
> racing patrol vehicles