Square taper BB replacement advice needed.

[Waterford 45]

I bought a Diamondback Ascent EX frame here recently to replace my identical (well almost - the new one is a size bigger, but might suit me better ) one I've had from new since 1992 ish. Unfortunately the cartridge square taper BB which was in the old frame wont come out. I've been looking around for a replacement, and (new) Shimano BB-Un300 seems to be one of the only options - although people have commented that they're not great (my expectations wouldn't be high for a €11 BB anyway). My chainset is a Deore MT-60.

I figure I need a 73MM shell - 122.5 spindle. But even at that there's a couple of sub types ie D-NL, and LL.

Does anyone know the difference between the two sub-types?

Alternatively, if there's anything better I'd consider them as well - used either.

Thanks.

https://www.bike-discount.de/en/shimano-bb-un300-square-taper-73mm-bsa-bottom-bracket

 

[grantoury]

The new Shimano bb un300 is fine. Its just that the old ones were better built, so will last (even) longer.
LL and D-NL has to do with chainlines for the corresponding (current) Tourney cranksets. It probably has no bearing on an old crankset. There is a "chainline stabilizer" on the right side, a little ring. Go for the D-NL, it has the lowest chainline.

 

[FluffyChicken]

Hi, they're not subtypes but Shimano cartridge markings.

The D-NL means 122.5mm length, the LL (should be LL113) means 113mm length.

You'll find MM107 and MM110 should be obvious and XL being 118 (should be marked XL11

Basically
SS, MM, LL, XL.
Short, medium, long, extra long
(103, 107, 113, 11

MM110 was added a year or so later to infill on new designs/mtb frame bands.

D-H, D-NL, D-EL for some reason used an abbreviated old marking.
115, 122, 127
But these are traditional lengths and the newer markings are for super low profile cranks that came along around 1992.

------
Technically these older marking tell you the axle length, offset from right and left and a few other things.
But for anything in the 90s onwards and especially cartridge style BBs, they are just standardised lengths in old markings. Go to older cup and come and you get loads of slight differences and lengths.

 

[FluffyChicken]

If you go back to the original MT60, you'll see old markings, the number in the code means 68,70,73

Go to the newer MT60-SG and you just get the D-NL 122 length to choose from, that the 47.5 chainline.
The old one would have a 6 speed option and hence shorter chainline, but newer only 7 speed.

 

[CassidyAce]

@Waterford 45 I have a nearly new BB-UN55 (73mm and 122.5mm) for sale for £10 + P&P if you want it. https://www.retrobike.co.uk/threads/£10-each-p-p-headset-stem-bb-saddle-swap.441616/

(However, the fact that you're quoting prices in Euros suggests that it might not be worth the hassle for either you or me.)

 

[Waterford 45]

 

[Waterford 45]

@Waterford 45 I have a nearly new BB-UN55 (73mm and 122.5mm) for sale for £10 + P&P if you want it. https://www.retrobike.co.uk/threads/£10-each-p-p-headset-stem-bb-saddle-swap.441616/

(However, the fact that you're quoting prices in Euros suggests that it might not be worth the hassle for either you or me.)

Thanks. I'll send you a pm (later today- might work out.

 

[Prodigal Son]

I bought a Diamondback Ascent EX frame here recently to replace my identical (well almost - the new one is a size bigger, but might suit me better ) one I've had from new since 1992 ish. Unfortunately the cartridge square taper BB which was in the old frame wont come out. I've been looking around for a replacement, and (new) Shimano BB-Un300 seems to be one of the only options - although people have commented that they're not great (my expectations wouldn't be high for a €11 BB anyway). My chainset is a Deore MT-60.

I figure I need a 73MM shell - 122.5 spindle. But even at that there's a couple of sub types ie D-NL, and LL.

Does anyone know the difference between the two sub-types?

Alternatively, if there's anything better I'd consider them as well - used either.

Thanks.

https://www.bike-discount.de/en/shimano-bb-un300-square-taper-73mm-bsa-bottom-bracket

Are you sure it´s 73 x 68mm?

 

[Waterford 45]

Are you sure it´s 73 x 68mm?

Bb shell measures 73mm

 

[legrandefromage]

https://www.ebay.co.uk/itm/20383535...QUqWfMfQUC&var=&widget_ver=artemis&media=COPY