UN55 bottom bracket size query

ade555

Hi

I need now bottom bracket for my daughter apollo bike, the current one have cups and bearing so looking to replace with seal cartridge, like Shimano UN55, I measured and looks like will need 70mm x 117 but I can only find 70mm x115, but then I got a bit confused about English and Italian Thread , anyone can put on right track?

Thanks
Ade

Nick Payne

Is the existing drive side cup left-hand thread? If so, it's not an Italian thread BB. Unless the crankarms and/or chainrings are extremely close to the frame with the existing BB, a 115 should be fine as a replacement for 117. You can always fit a washer under the fixed cup to give exactly the same chainline, but 1mm difference is neither here nor there.

POAH

English thread will only be 68 or 73mm wide while italian will be 70mm. if its a mountain bike its unlikely to be italian, are you sure you are measuring it right or is it for a road bike?

The Rookie

Apollos are English thread, but as quality control is an oxymoron on Apollo bikes it's probably a 68mm shell that is a bit oversize.

cooldad

Probably best to just replace the balls and add lots of grease.

ade555

I striped the bike completely and done rebuild over the last weekend, what a difference now, you are right about the quality but then again is not £££ bike, took my daughter to bike shop to check if she can use 26" wheels with small 14" frame but just not there yet and she did't feel comfortable, this will have to do for another few months until she grows a bit as I can't justified paying over £300 for specialized kids bike then sell in few months time for half the price, also did order 68x118 bb to fit which has arrived now.

Thanks for advice

The Rookie

Don't buy a £300 specialized, it will be dreadful quality!

ade555

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19750862#p19750862]The Rookie[/url] wrote:

Don't buy a £300 specialized, it will be dreadful quality!

I was referring to new kids bike prices, they want lot of money for nothing special.