Yes, you likely have a UN54 BB in there ... and it has a plastic cup. The reason they usually break is people overtighten them. The need not be torqued as the misguided instructions say! Just snug is fine. But hey, plastic is just a bad idea period, for anything in the BB.. and Shimano's use of it is inexcusable.
You can get a new plastic cup, but you may be wondering if it will crack too... not really fun. Another option is a new aluminum cup by Problem solvers called an Up-Cup #54. But, for the cost of the Up-Cup($15-20), you'd be better of just getting a new BB. Shimano now has UN-55's which use a steel cup, but I'd get a Tange LN-3922 from Tange. It's the same internals as the one Riv sells but is all steel. The Tange's do not have that silly lip on the cup that the UN55/54's do, therefore allowing more chainline adjustments than with the Shimano. A second choice would be the IRD steel cup BB, easier to find. I've gotten the Tange's from bike shops via ebay and online. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To view this discussion on the web visit https://groups.google.com/d/msg/rbw-owners-bunch/-/7iz6UU2lZE0J. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
