I bought, a while back, an enourmous adjustable spanner which works OK for this kind of non-standard job, or as locknut duty with a proper spanner underneath for headsets.
Go invest in one. I think the max is about 6 cm, works on my old BB cup that isn't a size that I have proper tool for. I also bought an adjustable pin spanner which has changed my life! Brilliant.
I bought, a while back, an enourmous adjustable spanner which works OK for this kind of non-standard job, or as locknut duty with a proper spanner underneath for headsets.
Go invest in one. I think the max is about 6 cm, works on my old BB cup that isn't a size that I have proper tool for. I also bought an adjustable pin spanner which has changed my life! Brilliant.