TimothyH

There is some misinformation out there regarding Shimano BB-7700 vs BB-7710 bottom brackets and hopefully this post will help someone avoid the confusion I went through. I believe this information is correct but am open to those who are more knowledgeable.

The BB-7700 is listed at many websites as a "sealed cartridge unit." It even says this right on the product. This is somewhat misleading as it is not a "sealed cartridge." Loose bearings are held in place by a plastic holder (cartridge?). The seals could also be called dust covers.



The loose bearing design requires preload adjustment during assembly and more frequent maintenance. Some track racers pack the bearings with light lube for less resistance and some run it without the plastic seals for the same reason. This bottom bracket is 173 grams. Light weight and low resistance but more frequent maintenance makes some feel that this bottom bracket is better suited to indoor racing and/or dry weather.


The BB-7710 uses true sealed cartridge bearings. No preload adjustment is required and there really is nothing to maintain. The 7710 is heavier than the 7700 - 230 to 240 grams - this in spite of the many websites which claim it is 173 grams. Better moisture resistance and easier maintenance make this bottom bracket more suitable for road and wet conditions. The 7710 bears the NJS stamp because Keirin racing is sometimes done in the rain.




-Tim-

nripin

great read appreciate you sharing this !

AndjaVXC

Agreed, good information. Terminology gets tossed around so loosely.

Leukybear 

Shimano did this on hubs as well. "Yes these are bearings and they are sealed inside there"

TimothyH

Follow up now that both are in hand. The 7710 is noticeably heavier and has noticeably more drag when spun by hand.


7710 on the left. 7700 on the right.




7710 on the bottom, 7700 on top. Interesting that both say NJS but the 7700 says Japan while the 7710 says Indonesia.




7710 bearing seals.




-Tim-

Leukybear 

The additional weight is from essentially what is doubled up bearing races. Looseball incorporates the BB cups themselves for races while cartridges have their own, in addition to what would've been looseball races that now instead function to envelope/ retain it). The drag is from bearing seals.


Adding to the discussion, the roadie, non NJS DA 7700 BB, is sealed cartridge. And fully backwards compatible.

Soil_Sampler

You can save a lot of coin by getting a 105 or a Ultegra , if you can find one.

Scrodzilla

105 109.5mm Octalink (BB-5500) are extremely easy to find for around 40 bucks.

Soil_Sampler

Not the Ultegra!

Nagrom_

Was gonna say, 5500 all day. 77's have always been a pain in the ass for me for some reason. Damn needle bearings.

Leukybear 

I actually un-NOS'd a BB-6500 just earlier this month

Soil_Sampler

Getting harder and harder to find!

TimothyH

What exactly about the 77 series is a PITA?

I'm not trying to challenge. Sincerely interested.

Soil_Sampler

I believe he is talking about the 7700 specifically. Greasing and adjusting.

Guillaume QC

Hi,

I know this thread has been dead for a while but i just got a used BB-7710 for 4 CAD $ and i am wondering if i could open it and service its bearings like you sometime see on youtube...

No i read what was said before and i understand it has a very unique bearing mechanism (more sealed than sealed bearing!!) , but do i have a chance at making this BB just a little smoother (it currently has a little crack sound now and then, very subtile, but id like to make things perfect!). If i really cant reach the bearings is there a way to spray some WD-40 and Lube later on??

Thanks in advance for your answers guys. This was my very first reply / question on BForum !!

Guillaume

bonsai171

WD40 is not for this job. Way too thin for bearings, and is a de-greaser.

Dave

Minion1

Clicking BBs are normally dead BBs, especially sealed bearing ones. $4 for a reason?