Which bottom bracket for my SS?

[MossCommuter]

Hi

My el-cheapo SS has a bottom bracket described as "Generic Cup and Axle"; I want to replace it with a sealed cartridge (Shimano).

How do I know how to choose which sealed cartridge? I can see they come with different spec's (68 x 117.5, 68 x 113,...) and prices vary quite a bit too.

And when I've got one, do I need any special tools to get this "Generic Cup and Axle" out? I have the tools to put the new one in (I think).

thanks

 

[GrumpyGregry]

any chance of a pic?

 

[MossCommuter]

The bicycle is one of these: http://www.pisquaredbikes.com/

There are pics there and a full spec' sheet. Picture 4 shows the crank and BB.

What specific pictures did you need? I can take some if those on the website are no good.

 

[RecordAceFromNew]

How do I know how to choose which sealed cartridge?

With only the info you provided it is impossible to give you an answer with any degree of reliability. Your objective is to maintain the chainline when the BB required is dependent on the chainset, and this covers the removal of traditional BB as well as anything else around.

 

[RecordAceFromNew]

Picture 4 shows the crank and BB.

It seems to me that pic shows the BB has Shimano splines, like below? If so the best is to remove it and measure the spindle length (or read what it says on the body) given there is nothing much one can gather from the chainset...

 

[MossCommuter]

Ah, OK - I see; that all makes sense - to work out which length of BB I need to actually remove the old one and measure it.

thanks

 

[ayceejay]

The big advantage a sealed unit has over a "cups and axle" unit is ease of maintenance but since one of the best (strongest/smoothest) bottom brackets is of the cup and spindle configuration is maintenance a problem for you?
http://www.amazon.com/Sugino-75-Track-Bracket-English/dp/B001F73I6K

 

[MossCommuter]

Thanks for the suggestion but this is a really inexpensive bike so expensive components are a waste; the maker's website recommends replacement with a sealed unit too so that's what I set out to look for. I am not very mechanically minded either so simplicity what I need

 

[MacB]

when you've measured your existing axle, which I'm guessing is square taper, I have a couple left over from my various chainline experiments. I'll check the sizes tomorrow and post back but if we have a match then you're welcome to one FOC. They are brand new having only been fitted then removed once I realised I'd miscalculated again.

 

[MossCommuter]

WOW @MacB that's very nice of you! It'll be weekend before I can get the existing one out but I'll reply again when I do.

I wish I could reciprocate with an Envy X2 or something but, well, I can't LOL

 

[MacB]

you're welcome, they are only sitting in a drawer anyway, as I said I'll post up the sizes tomorrow, I think I have 3, just luck of the draw if one of them is what you need.

 

[I like Skol]

I haven't seen anyone mention measuring the BB shell width. This is as important as the axle length, it should be either 68 or 73mm. once you have that measurement and the axle length you should be good for ordering the correct size. Measure axle length from end of taper to end of taper, if it is one of the axles that has the threaded bits at the ends ignore them.

 

[MossCommuter]

I have a couple left over

it should be either 68 or 73mm. once you have that measurement and the axle length

Everyone! thanks

Turns out it's a 68x113 mm

 

[MacB]

yep, got one of those, start a new conversation/PM to let me know where to post it and I'll sort....Al