Chain Rings 50.4mm BCD Posted on 07 Feb 11:15 , 0 comments
OK chainrings may not be the most interesting topic but they are one of the most visible parts of a bike and determine "the look" of a classic bike. For many years the Stronglight 49D and T.A. "Cyclotouriste" (AKA Pro 5 Vis) were the most popular of alloy cotterless chainsets and to many a vintage or classic bike looks perfect with one fitted. Both of these models used the same 50.4mm Bolt Circle Diameter (BCD) to mount the outer chainring to the crank. However the inner ring BCD, where the inner ring bolted to the outer was different between the Stronglight and TA products., so you could swap the pairs of rings but not individual rings between the two manufacturers. Also the Stronglight 49D was only ever sold as a 52 teeth/42 teeth double, whereas the T.A. Cyclotouriste was available in singles doubles and triples in a huge range of sizes down to 26 teeth for the inner and as many as 60 teeth for the outer. so many cycloists fitted their Stronglight 49D cranks with TA rings.
Many of these cranksets survive and need new rings. Both TA and Stronglight are still going strong as manufacturers of rings and chainsets (in the case of Stronglight), but only TA still make the 50.4mm BCD rings and they are to special order. Velo Orange make a few sizes and SunXCD are launching their own in April 2015. There will be 48T, 46T, 44T for outer and 30T, 28T for inner chainring. Prices will be available soon. We stock a range of new TA rings which we specially order every few weeks.
Both Velo orange and SunXCD make new 50.4mm BCD cranksets. The VO ones are more like the Stronglight and the SunXCD are more akin to the T.A. Cyclotouriste. We sell both makes, although the V.O. ones were unavailable for a while and the SunXCD are more popular with our customers.
See the range here