PF30 BB Shell Size

[MikeB]

Color me confused when dealing with the PF30 standard. I thinking of going with a PF30 on the next build and have some questions.

Paragon has PF30 BB shells in 68 and 73 mm and that’s where my confusion starts. If you press in the bearings, the overall dimensions of the BB from bearing race to bearing race will only be around 72 mm for the smaller BB shell. Don’t most BB30 cranks need an overall bearing to bearing distance of around 95 mm. Do you use 20+ mm of spacers in this case, or do I need a bigger PF BB shell?

My Pivot Mach 4 has a PF BB that uses a 24 mm spindle, and the BB shell is around 92 mm wide.

The issues with mounting it in my jig, and finishing it after the build, may steer me away, but at this point I’m a little confused on the size issue.

Any help would be appreciated.

[Dornbox]

I believe you can use the 68 for both road and MTN but you'll need spacers with the SRAM/Truvative stuff MTN Stuff. In short, 68 for road and 73 is for MTN. I'm not sure about your 92mm Mach 4...?

Check out:

Glory Cycles Product Reviews: SRAM and Truvative Crank Compatibility with BB30 PF30 Frames

[progetto]

Mike,
Short version
BB30= 68 or73mm wide x 42mm id shell,bearing pressed directly into shell -30mm alloy axle on crank - cannondale free patent to industry
PF30= 68 or 73mm wide x 46mm id shell, bearing in plastic sleeve then inserted into shell - 30mm alloy axle on crank
Shimano press fit= 86.5mm wide x 41mm id shell, bearing in plastic sleeve then inserted into shell - 24mm cro-mo crank axle- also available in other widths.
Bill

[ApplemanBicycles]

+1 for what progretto said in above post on the size/width.

Both non and BB30 cranks have roughly the same Q-factor (at the pedal), but they have different width at the center of the BB.

Non BB30 cranks have bearings 9X mm apart, therefore the cranks are nearly straight and parallel to one another.

BB30 Cranks bearings are 6X mm apart. therefore the crank is essentially an S-bend in shape... resulting in a bit more "ankle clearance"

I hope that helps.

[johncaletti]

What cranksets are available for road in PF30?
how about mtb?
Looks like SRAM PF30 mtb cranks can use a 68mm shell with spacers, is that the case for others (can a 68mm PF 30 shell be used on road and mtb?)

thanks

[Dornbox]

(can a 68mm PF 30 shell be used on road and mtb?)

John,

Yep! As you pointed out in your post, you'll need to use the spacers that are included with the PF30 cups to use a Mountain crank (73mm) and drop the spacers for a Road crank (68mm).

[zank]

What cranksets are available for road in PF30?
how about mtb?
Looks like SRAM PF30 mtb cranks can use a 68mm shell with spacers, is that the case for others (can a 68mm PF 30 shell be used on road and mtb?)

thanks

John, you can use any BB30 crank with PF30. You just need to get the PF30 cups/bearings separately.

I've never gotten spacers with a PF30 BB. If it is for a mtb, I'd use the 73 mm shell. I have a BB30 XX crank at the shop, and I don't think it would work. I will double check, but I believe the axle is stepped down inboard of where the bearings would ride. If you went with a narrower shell and the bearings were more inboard, you might be in the 30 mm OD area of the axle. I'll confirm later today.

[Dornbox]

If you went with a narrower shell and the bearings were more inboard, you might be in the 30 mm OD area of the axle. I'll confirm later today.

Zank, the spacers are for the cups/BB not the cranks making the shell an effective 73mm wide, same as the standard BB kits. Admittedly, I've only just geared up to do PF30 bikes but I've got 5 in line so I've been lurking fairly seriously. Also, my bad, the spacer kit is sold separately for $8-9 retail.

[zank]

Ah, that makes sense. Thanks for the clarification.

[Archibald]

The 92mm wide shell is Shimano's BB92. A different kind of press fit than PF30 and in some folks opinion, my own included, it's better for MTBs. That said, I don't know if it's going to maintain traction; we should know after Sea Otter.

[progetto]

Don,
There are quite a few big companies ( giant, scott being two ) who have been using the Shimano system for about 4 seasons on the road, great if you only use Shimano but not really adaptable to any other brands. Trek has there own design also that has adapters for Shimano-Sram-Campy based loosly on Shimano dimensions. You can also use the big 3 on bb30 or PF30 using appropriate adapters. Campy make there own while wheels manufacturing make a Shimano or Sram adapter. I guess it's another argument for custom, " tell me what your using and I'll build it for you".
Bill

[MikeB]

As a way to summarize what I’ve learned in this thread, I’ve put this together. Please correct me if I’m wrong:

BB86, BB90 or BB92 – The titles given to the standards where the bearings are pressed in, the crank spindle is 24 mm (most normal external BB standard cranks will work), and the number following the BB is the nominal BB width. So BB92 would be 92 mm wide when including the two 2mm thick bearing cups.

PF30 -- The titles given to the standards where the bearings are pressed in, and the crank spindle is 30 mm. The BB shell size is 68 mm for road, 73 for mtb. However, spacers can be placed between the bearing cup and frame to run a mtb crank on 68 mm “road” shell.

BB30 – The same as the PF30 standard, except the bearing press into the frame and are stopped by a snap ring inside the BB shell. Using spacers on a BB30 shell are not an option.

I have also read that BH Bikes and FSA have worked together to produce yet another standard (BB386EVO) that will work with all 30 mm spindle cranks and will be released at Sea Otter.

[progetto]

Mike,
Pretty much right except PF30 the bearings are contained in a plastic sleeve which is pressed the shell, It was designed to be more tolerence friendly, same would be true for bb86 etc.
Bill

[e.Gellie]

So what reamer/facing tools are people using with PF30? I believe the BB shell outer faces need to be faced also ...

[progetto]

So what reamer/facing tools are people using with PF30? I believe the BB shell outer faces need to be faced also ...

Ewen, I've got one of Tony Maietta's PF30 reamer's here with the large Park head tube facer, PM if you want a loan for a one off if you want to sample, I'm at the other end of Aus near Dazza but can Post.

[JFW]

So guys, what's the verdict here? I got three 29er frames lined up that will most likely use press fit bearings. I'm all for the BB92 standard. Will it develop into a standard? Alternatively: Are the cups reusable with new bearings in them? (heck one could just machine a set of alu-cups, I guess..).

Truls

[VertigoCycles]

So guys, what's the verdict here? I got three 29er frames lined up that will most likely use press fit bearings. I'm all for the BB92 standard. Will it develop into a standard? Alternatively: Are the cups reusable with new bearings in them? (heck one could just machine a set of alu-cups, I guess..).

Truls

I don't see an advantage for the BB92 at all when the standard BB puts the bearings in the same place, the bearings are easier to replace and you (and whoever will be servicing the bike) probably already have the tools necessary to build and service it. Also, the shimano bearings continue to be relatively cruddy when it comes to preventing junk from displacing the grease and a King BB is a fantastic substitution (and up-sell). Officially, the Shimano delrin cups are not reusable though you can pull the bearings to replace them if you have the proper tool.

[e.Gellie]

Ewen, I've got one of Tony Maietta's PF30 reamer's here with the large Park head tube facer, PM if you want a loan for a one off if you want to sample, I'm at the other end of Aus near Dazza but can Post.

Thanks Bill, that's nice of you to offer, I'll get in touch,
Ewen