are ramped and pinned chainrings necesary for 7 spd indexing?
06-19-12, 05:35 PM
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are ramped and pinned chainrings necesary for 7 spd indexing?
I have a soma steel cross bike set up with 7 speed indexing and I need to replace the chainrings as they are worn. I have older chain rings that I could use but they are not ramped and pinned. I realize the shifting might be a bit slower but this should work, right? I guess the easiest is to just try them out and see what happens but perhaps someone has tried this out and can give me an answer.
06-19-12, 05:51 PM
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they are not needed for any speed, but they help a lot.
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06-20-12, 04:23 AM
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06-20-12, 05:40 AM
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Basically you'll need to ease off the power to shift the front reliably.
06-20-12, 11:03 AM
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I did this on my ancient steel-framed Trek 620 -- works great.
Crank is a Sugino 7-sp triple circa 1983.
Just bought 7-sp SIS brifters on eBay. My existing SunTour FD didn't work (wrong pull ratios) but that was easily fixed with a new low-end Shimano FD.
It isn't as crisp as it could be but it is waaaaay better than friction shifting.
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Crank is a Sugino 7-sp triple circa 1983.
Just bought 7-sp SIS brifters on eBay. My existing SunTour FD didn't work (wrong pull ratios) but that was easily fixed with a new low-end Shimano FD.
It isn't as crisp as it could be but it is waaaaay better than friction shifting.
Jump in; the water's fine.
-Tom in SoCal
06-20-12, 02:55 PM
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Thanks for the replies; these are very useful. My first post wasn't as clear as it could have been. I am using shimano bar end shifters so the front triple is not indexed. I suspect that while a pinned and ramped chainring would help, it is not a big deal when relying on friction for the front shifting.
06-20-12, 04:20 PM
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Front chainrings generally don't care how many speeds you have in the back, provided the chain you're using is compatible. Ramps and pins will allow for better front shifting under load, but you should be in the habit of easing your pedal force anyway when shifting. They do, however, make it a bit easier to shift with friction though, since there's less need to overshift and retrim.
