Chain ring rubbing chain stay
05-09-19, 05:35 AM
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Chain ring rubbing chain stay
I have an older (96?) Tomassini Tecno that I love to death but I've noticed that the inner chain ring will sometimes rub on the chain stay. I see about 1-2 mm of clearance, and it looks pretty tight. I think it touches when I am mashing as the frame flexes. How do I resolve this? The paint has been completely scraped off in this one spot. My BB is a sealed square taper cartridge. I don't see how a spacer is really going to resolve anything as the cups on both sides have these lips that cover the BB shell. Do I need to change to entirely new cranks with external BB cups in an effort to move the entire crank? That seems like a lot for just a few more mm of clearance. Any ideas?
05-09-19, 06:16 AM
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There a spacers that can be fitted to move the BB over. Usually in 2.5mm increments.
05-09-19, 06:48 AM
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Adding spacers between the shell and the lip on drive side of your cartridge should resolve your issue. This moves the spindle on that side out a bit, which means that it will move inwards on the other side. If your spindle is of appropriate size, then no big deal. If your spindle is too short, the spacers may cause problems on the non-drive side, in which case you would need a new cartridge.
05-09-19, 09:28 AM
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Are you certain it's not rubbing because the bb is worn out?
05-11-19, 08:50 AM
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One thing I remember from my PX10 days, the double CW spindle was slightly longer on one side than
the other, with the longer side meant to be on the drive side, but the difference was small, so maybe
a prior owner inadvertently flipped the spindle. In your case with a sealed unit, it is still possible
the BB is backwards if the cups are separate.
the other, with the longer side meant to be on the drive side, but the difference was small, so maybe
a prior owner inadvertently flipped the spindle. In your case with a sealed unit, it is still possible
the BB is backwards if the cups are separate.
05-11-19, 09:33 AM
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You didn't tell us which crankset and BB you are using.
=8-)
=8-)
__________________
5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
