# Best replacement of Shimano SM-BB70 / discontinued?



## spleeft (May 2, 2017)

Tall Boy 2 R , need to replace bottom Bracket.
I know it 73mm ( it had one spacer on drive side)but what other dimensions need to be correct? Spindle size ( what is it ? ) or are they all standard?
will provide more info if needed, thanks!


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## Sparkman999 (Dec 19, 2017)

Lots of options for 73mm threaded BB for a 24mm Hollowtech spindle. Wheels Manufacturing, Raceface, etc. Jenson website has a good filter so you can see the options. I’ve heard of others replacing the bearings in the BB70’s so that may be an option for you too.


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## spleeft (May 2, 2017)

This BB is pretty over due / rusty / so I def should just replace. Is there an option that has serviceable bearings / better for mountain bike / kinda nasty-harsh conditions? Or is it standard to just always replace entire BB. ( not just service bearing) ?


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## Sparkman999 (Dec 19, 2017)

There are BBs that are more serviceable (ie designed to replace the bearings, although you may need specialty tools). The Wheels Manufacturing ones being an example. A lot of BB’s are just cups that hold the bearings and these cups are screwed into the BB housing. There’s typically a plastic housing that connects the two cups in order to prevent crap and moisture that gets inside the frame from coming into the bearings.


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## eb1888 (Jan 27, 2012)

You'd be surprised how serviceable your bearings are. Pry off the Do Not Remove plastic cover a little at a time around the outside. 
Do the same around the inside of the seal you'll see. Flush and work the bearing with Liquid Wrench until it has all the gunk out and is rolling smoothly. Use the seal to repeatedly push bearing grease or marine grease for wet riding into the bearing until it comes out the back clean. Do both sides and assemble. 
Even if you get a new bearing you should load it with grease. They often have almost none.


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## J_Westy (Jan 7, 2009)

I recently replaced mine with a BB93...

Is it the “best”? Arguably not, but a solid, easy choice I think that will last a long time like the original BB70 did.


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## spleeft (May 2, 2017)

Thanks for the replies/advice. Parts ordered. Happy New Year!


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## RAKC Ind (Jan 27, 2017)

Bb70's are all over the place. I usually watch out for deals and grab a couple each time as my fat bike (raceface crank set but replaced bearing cups with shimano for better reliability).

Google has probably 100 listed cheap and for sale. Its just a shimano XT/SLX bottom bracket. Far from outdated seeing as they are used on the newest of bikes with shimano cranks.

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## noapathy (Jun 24, 2008)

Updated version is called BB-MT800 (XT level). They say smaller bearing and better sealing makes it better. I still rebuild my old ones in the winter so I may never know. :lol:

Shimano XT BB-MT800 Bottom Bracket | Jenson USA


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## eurochien (Jan 16, 2011)

noapathy said:


> Updated version is called BB-MT800 (XT level). They say smaller bearing and better sealing makes it better. I still rebuild my old ones in the winter so I may never know. :lol:
> 
> Shimano XT BB-MT800 Bottom Bracket | Jenson USA


It's not the same. I've ordered one thinking it'd be compatible with my Yeti ASR bottom bracket shell but the cups are much smaller in diameter.


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## noapathy (Jun 24, 2008)

eurochien said:


> It's not the same. I've ordered one thinking it'd be compatible with my Yeti ASR bottom bracket shell but the cups are much smaller in diameter.


Just because it doesn't fit your bike doesn't mean the BB70 and the BB-MT800 aren't equivalent (hint, they are). It means you didn't do your homework to figure out what you have.


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## eurochien (Jan 16, 2011)

noapathy said:


> Just because it doesn't fit your bike doesn't mean the BB70 and the BB-MT800 aren't equivalent (hint, they are). It means you didn't do your homework to figure out what you have.


You are right, I didn't. I stand corrected.


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## J_Westy (Jan 7, 2009)

eurochien said:


> It's not the same. I've ordered one thinking it'd be compatible with my Yeti ASR bottom bracket shell but the cups are much smaller in diameter.


I'm curious, why does the smaller outer diameter make it not compatible with your bike?

I switched to a BB93 without issue... it came with a tool adapter to install it with the "old" style tool.


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## noapathy (Jun 24, 2008)

J_Westy said:


> I'm curious, why does the smaller outer diameter make it not compatible with your bike?
> 
> I switched to a BB93 without issue... it came with a tool adapter to install it with the "old" style tool.


I thought about it as well. If it's the bike in your profile (2010 ASR Carbon) it would appear to be the correct BB for the frame (68/73 BSA)...except for one thing. This pinkbike article says the '11 comes with a 68/73mm GXP BB, so the spindle diameter would be different on one side. I can't find the '10 spec sheet to confirm, but yeah, that would be a problem with a SRAM crankset.

P.S. Nice bike!


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## eurochien (Jan 16, 2011)

I did not realize the cheapo thingy was an adapter. I was surprised at the smaller size of the outside cups, which made me think that I had ordered the wrong BB (another goddam standard). My cranks are old XTR so I guess it would work, I just need to try again.


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## noapathy (Jun 24, 2008)

Frustrating, but should be good to go. :thumbsup:


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## One Pivot (Nov 20, 2009)

Bang out the bearings and replace them with Enduro angular contact bearings. It's close to as good as it gets for a bb, and it's affordable.


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