The Sedis Sport was the first widely sold narrow chain. It was paired with the Stronglight 93 as standard equipment on millions of French bikes. The problem may be the geometry of the setup, i. e. ring combination, axle length, FD positioning, etc. Also, the Stronglight 93 wasn't seen that often configured as a triple, that usually being the role of the Stronglight 99. Maybe the previous owner converted to a triple and didn't use the proper spacers. The discarded chainguard brings up another point. Did the chainring bolts run through the chainguard? If so, removing it might have left the bolts to long. If the previous owner foolishly took up the length with thicker spacers, then the chain would very likely jam between the chainwheels.
Regards,
Jerry Moos Houston, TX
Joe Bender-Zanoni <joebz@optonline.net> wrote: Some earlier cranks are definately unfriendly to narrow chains. In general, I find everything in the drivetrain tends to work best with the correct era chain. I'm not sure about your Stronglight but earlier Sugino Mighty Tour cranks for example will suck a narrow chain right between the rings.
Joe Bender-Zanoni
Great Notch, NJ
> I have a new bike ( Clean 1973 Raleigh Gransport, $75 shipped,
> whoo-hoo!) with a Stronglight 93 crankset. A previous owner chucked
> the outer chainguard, moved the middle ring to outer position, added a
> 48T middle ring, to get a triple (42 - 48 - 52)
>
> The chain looks like an early 1990's sedisport.
>
> Shifting from middle ring to large ring, the chain frequently jams
> between the chainrings. These are original 1970's stronglight rings
> which have a shoulder on one side only. The shoulder on the side
> where the countersunk hole for the chainring bolts is. In its current
> configuration, the shoulder from inner-middle-outer when looking down
> while riding in the saddle are on the left, left, right. This keeps
> the middle and outer rings as close as possible together, flat-side of
> these rings against the spider.
>
> When i shift onto the middle ring, the chain appears to be centered
> between the inner and outer rings.
>
> Is this crankset unfriendly to narrow chains ??
>
> - Don Gillies
> San Diego, CA