BB spacers for adjustment on fixed conversion
03-26-06, 09:23 AM
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BB spacers for adjustment on fixed conversion
I am doing a cheap fixed-gear conversion and have replaced the previous cranks. The cranks I have now are old Shimano 600 (FC-6207) and the BB shell is 70mm with English threading. From whatever online sources I have been able to find, the cranks take a 116mm spindle. I am ASSUMING that this yields the Shimano "standard" chainline for a road double of 43.5 mm. To match my rear chainline, I want to be able to move my front chainline in. I have put the cranks up against the frame and there is plenty of clearance.
Since I am not sure of the measurements, my current thinking is to buy a short (107-110mm) spindle BB for 73mm shell and then get a combination of spacers to allow me to adjust outward. Does this thinking make sense?
Also, if this works, I saw a note in Barnett's manual that says that cartridge BBs "with plastic cups will not accept more than 1mm of spacer thickness under the main assembly flange." As the Shimano BBs I have been looking at have plastic cups, it seems that I may need another option. Any recommendations?
Thanks in advance.
Since I am not sure of the measurements, my current thinking is to buy a short (107-110mm) spindle BB for 73mm shell and then get a combination of spacers to allow me to adjust outward. Does this thinking make sense?
Also, if this works, I saw a note in Barnett's manual that says that cartridge BBs "with plastic cups will not accept more than 1mm of spacer thickness under the main assembly flange." As the Shimano BBs I have been looking at have plastic cups, it seems that I may need another option. Any recommendations?
Thanks in advance.
03-26-06, 06:08 PM
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Increasing the BB cup spacer thickness increases the stress on the cup's shell and threads, which is why they recommend the 1mm limit for plastic.
I have seen lots of fixers simply mount the chainring in the inner road double position.
I have seen lots of fixers simply mount the chainring in the inner road double position.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
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Schwinn: 1988 Project KOM-10, S/N F804069
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
03-26-06, 10:37 PM
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70mm and english threaded? Are you sure its not either swiss, or 68mm?
What I'd do is measure the crank with a known spindle, and measure the chainline. That will tell you how far you need to go.
What I'd do is measure the crank with a known spindle, and measure the chainline. That will tell you how far you need to go.
