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chainring interchangeability - 8, 9, 53A, 53B, 42(5 posts)

chainring interchangeability - 8, 9, 53A, 53B, 42sweathog
Oct 16, 2003 10:09 AM
Thinking of putting an old 600 Ultegra-8 42 on my new 105-9 53/39 crankset. How about it? If it's no go and I want to get a new 42, would I also have to get the 53A which is listed as mating with 42? Thanks in advance.
Why?C-40
Oct 16, 2003 11:32 AM
The 53/39 is the most common because it makes more sense. With STI or Ergo it's simple to upshift or downshift two cogs after a chainring shift. In the old days of friction shifting, the 53/42 only required a 1-cog shift, which was easier to do accurately. Nowdays it makes little sense, unless you ride on total flatlands with a 11-19 and don't need a gear as low as a 39/19.
of course...Steve_0
Oct 16, 2003 11:35 AM
then you dont need the 53 either. split the dif with a 46, and save precious grams.
It will work alrightMR_GRUMPY
Oct 16, 2003 11:52 AM
The only problem that you might have is that you may have a delayed shift when you shift between rings while standing. If you are sitting, you might not notice any difference.
re: chainring interchangeability - 8, 9, 53A, 53B, 42sweathog
Oct 16, 2003 1:27 PM
OK, thanks, I guess I'll just throw it on there and try it, I don't shift front rings while standing anyway. To answer the question "why," it is to reduce the number of front shifts I make. I live in a totally flat place and use as close to a "straight block" as I can get in order to have one-tooth shifts. With the 39 and a 13-23, the highest smoothly usable ratio is 75 gear inches (remember them?); 39x14. This is a gear I ride in a lot, but I also like 80 a lot, but the 39x13 is not smooth so I have to make a front shift. With a 42 I could eliminate this shift because the 42 effectively moves the cogs over one compared to a 39. I'll now throw out a related question: I could avoid more front downshifts if my new 53 ran more smoothly with the 19, the third cog from the inside. Any adjustment suggestions?