Help finding a replacement crank bearing

[toneboy1]

Hi,
I'm not sure how the sizing works, but I'm looking for an equivalent replacement for my current:

Shimano BB-UH25
68 DB
BC1.37x24
<- D-NL ->

This is because I can't find an exact replacement for sale.

Can someone please explain the nomenclature of the sizing and model works. I don't understand why it says D-NL, the other ones I've seen are a size in mm.

Thanks in advance for your help

[find_bruce]

Welcome outside toneboy. What sort of bottom bracket is it - it sounds like a square taper. Like you I have only seen sizes in mm but I did find this image on te interwebs


I would suggest measuring the bottom bracket - end to end in mm is what you want, then its just a matter of getting the appropriate size - UN26 or UN55 are the currently available Shimano square taper bottom brackets

[toneboy1]

Thank you for the greeting and the reply.
That is almost exactly it, except instead of "EF" it says "DB". (Yes, square taper.)
So I've done a bit of research but I'm not 100% sure what D-NL is. I've heard that it is 122.5mm axle length. However, for instance- chain reaction cycles don't sell 68mm width for 122.5mm long for the UN-55 (I've decided to go with a 50+ rather than the UN-26).

I might have to dismantle it again and measure the length....

Edit:

Do you think I could get away with using the 118mm or 127mm? What would be the harm in using a longer one?

Cheers!

[Duck!]

A longer spindle will locate the crank further outboard, possibly beyond the swing of the front derailleur to shift to the big ring. Too short can prevent the derailleur from shifting to the small ring, and can cause the rings or even crank arm to foul on the frame.

[find_bruce]

Pushys have a 122mm for the same price as Chain reaction $33 plus shipping

Also I came across the exploded view of bb-un55 which shows the widths as being MM110 / LL113 / D-H / XL118 / D-NL / D-EL

This seems to be consistent with D-NL being 122mm

[queequeg]

This might help:-

https://www.bikeforums.net/bicycle-mech ... -nl-r.html

Brad
"D-NL" is Shimano's code for the 123mm length. They also use "D-H" for the 115mm, "D-EL" for the 127mm, and are prone to throwing extra letters into the others, like "MM110" and "XL118". Don't ask me why.

[toneboy1]

Thank you all very much for your informative help.
I found a 55 series for $35.25 free postage, very excited to see the difference between my 2006, 25 series, which has about 8 years of good use. Not sure if this is normal practice, I have mainly used my bike to go to Uni, and since moving to flat as a tac Adelaide, to work everyday.

[toneboy1]

Update:
I did a comparison of my old UN-25 to my new UN-55 and there is definitely more static friction with the new one (UN55, it feels a bit like a stepper motor), and the dynamic friction (when the axis is in motion) seems about the same. (No noticeable static friction spinning the UN25 with my fingers) Do you think the new one will wear-in?
Riding to work today I didn't notice a difference.

Cosmetically, there is definitely rust on the old UN25, but do you think it was really worth changing?

Also, I see that this one is "Via Indonesia", not Via Singapore. Are these as good?

Cheers

[Duck!]

"VIA" marked on many Shimano bits is something to do with Japanese transport standards compliance, and nothing to do with the commonly-used Latin-derived term for "by way of...".

Shimano have facilities scattered throughout Asia; location of manufacture doesn't really have any bearing (pun not intended) on quality.

The UN55 BB has better bearing seals than the cheaper models, which does translate to a slight increase in friction when new.

[toneboy1]

Glad to hear there is nothing out of the ordinary or to be concerned about, thanks.
Still not convinced on the virtue of replacing as preventative maintenance, maybe next time I'll consider if corrective maintenance isn't the way to go instead.

Thanks to all