Need a lower gear
#1
Genius
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Need a lower gear
After attempting a steep grade in my new hilly home today, I realized I need lower gearing for a century comming up in two weeks. I also don't mind sactificing my topmost gear, so I think I might change both chanrigns.
Currently, I'm running Hyperglide 13...28 in the back. In the front, I have 42,52 Biopace. I'm tending towards choosing a smaller set of chainrings rather than a larger casette. First, I'd like to get of the Biopace. My questions...
So far, on combination that creates the lowest position for the chain at the FD, I have about 12 mm of clearence between the chain and the bottom of the FD. Any idea how small of a chainring I can get without needing to move the FD? The bike is older and I'd rather not need to move the FD.
Currently, I'm running Hyperglide 13...28 in the back. In the front, I have 42,52 Biopace. I'm tending towards choosing a smaller set of chainrings rather than a larger casette. First, I'd like to get of the Biopace. My questions...
So far, on combination that creates the lowest position for the chain at the FD, I have about 12 mm of clearence between the chain and the bottom of the FD. Any idea how small of a chainring I can get without needing to move the FD? The bike is older and I'd rather not need to move the FD.
#2
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Biopace 52x42 is almost certainly a 130mm BCD crank. Biopace was also made for 110mm BCD but those were typically triples with 48x38x28 or 46x36x26.
The smallest round ring for a 130mm bolt circle is 38. I believe the smallest Biopace for 130mm is 40 but you may not be able to find one.
If you get a smaller large ring, you will probably want to lower the front derailer - about 2mm per tooth reduction (e.g. if you go from 52 to 50, lower the front derailer by about 4mm) - or you may have poor shifting.
The smallest round ring for a 130mm bolt circle is 38. I believe the smallest Biopace for 130mm is 40 but you may not be able to find one.
If you get a smaller large ring, you will probably want to lower the front derailer - about 2mm per tooth reduction (e.g. if you go from 52 to 50, lower the front derailer by about 4mm) - or you may have poor shifting.
#3
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if you need a lower gear than 38x28, you will need a different crankset.
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Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
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Biopace 52x42 is almost certainly a 130mm BCD crank. Biopace was also made for 110mm BCD but those were typically triples with 48x38x28 or 46x36x26.
The smallest round ring for a 130mm bolt circle is 38. I believe the smallest Biopace for 130mm is 40 but you may not be able to find one.
If you get a smaller large ring, you will probably want to lower the front derailer - about 2mm per tooth reduction (e.g. if you go from 52 to 50, lower the front derailer by about 4mm) - or you may have poor shifting.
The smallest round ring for a 130mm bolt circle is 38. I believe the smallest Biopace for 130mm is 40 but you may not be able to find one.
If you get a smaller large ring, you will probably want to lower the front derailer - about 2mm per tooth reduction (e.g. if you go from 52 to 50, lower the front derailer by about 4mm) - or you may have poor shifting.