Bicycle Mechanics - Bianchi Gold Race 100 bottom bracket
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Hello from a long time lurker! I have a question regarding the bottom bracket on my Bianchi which I was hoping somebody can help me with.
The bike is a gold race 100 and around 9 years old. The BB clearly needs replacing, however I am struggling to find information on the parts. According to:
the bottom bracket is a Thun cartridge and the chainset is a Tracer 212RD. The outer ring has six dimples and I think a Park tool will fit.
I would like to replace the part with a Shimano BB, does anyone know if this is possible and will I need a new crankset as well?
09-28-09, 06:08 AM
Based on your description of the 6 notch outer ring, it sounds like you have an adjustable cup and cone bottom bracket. I'd be a little surprised to find an adjustable cup and cone bottom bracket on such a modern bike but I guess it is possible. What does the non-drive side cup look like? Does it have 2 large flats? That would confirm my guess.
If I'm right, you have a square taper crankset and should be able to easily find a Shimano cartridge bottom bracket that will drop in and not require any other changes. Simply measure the spindle and get the same size as a replacement. Will you be doing the installation yourself?
Googling Thun bottom bracket brings up results for 6 notch BB tools like the low end Campy square tapers, which jives with the description of being a cartridge BB.
Makes me wonder whether you crankset uses a ISO taper, however, googling the crankset brings up some other bike specs that seem to use this crankset with Tiagra and Sora components which would be JIS taper.
Either way, you should be able to replace it with a Shimano unit and keep your crankset, but I'm too lazy to chase any further BB specs at this time.
The Thun cartridge should come out with a Park BBT4 tool or equivalent.
09-28-09, 07:25 AM
Not sure why I ignored the word "cartridge" in your description but if I had thought about it longer, my reply would have been more like Steev's.
that was helpful, sounds like I can move to a Shimano BB. To be honest the supplied chainset is rubbish but I recently found some nice TA rings, so I want to keep it for as long as possible.
The Park BBt4 looks ideal for the drive side, the other side has 20 notches. Will get the tools and try and get the thing out!
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