Need help understanding Force cranksets
 

So I bought a new road bike after many years and I know nothing of the new BB/Crankset standards. It is setup with Pressfit 30 and Force compact 2012 (I guess) crankset. I wanted to get ready to maintain it so was looking into how to pull the cranks. But looking around SRAM's site I see nothing that matches my cranks. My cranks have a 10mm hex fixing bolt on the left side. It appears to be captive by a threaded ring that is installed by a pin spanner. I don't see anything like that on SRAM, but I see a number of examples for sale on e-bay, so I'm guessing this is an OEM setup that SRAM doesn't advertise?

It seems pretty obvious just to remove the 10mm bolt and the left side should pop off and then just pull the right side spindle and crank as a unit. But I am wondering how to properly install. I see reference to "preload adjuster" but from looking at it I don't see anything like that. I don't really want to pull it until I know I can get it back together correctly (only have a few 100 miles on the bike and don't really want to mess it up).

I see many references to SRAM GXP but is that mtb only, or if not is a SRAM GXP crankset compatible at all with Pressfit 30? I guess I don't get the whole deal with "wavy washers", spacers, etc. I'm used to square taper -- just install the cranks and go.

Thanks (for reading and any knowledge you can impart)

scott s.
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What did you,first , get out of the SRAM website ?

Search, get http://waa.ai/7jO

SRAM Force crankset users guide: http://cdn.sram.com/cdn/farfuture/1n..._cranksets.pdf

Just asking OP, what do you mean "to maintain it". This should run for years without any service. Except for the learning experience, which is not to be discounted, why are you messing with it after a just a few 100 miles. All sealed bearing cartridges there, nothing to do BUT mess it up. Just leave it be, and come back some years down the road when you really need to.

Okay, if you are a tinkerer and absolutely have to pull this apart to see what it is about, I understand. I'm just saying it isn't necessary or recommended. No other good can come of it.

There is nothing in a bb30/pf30 system to maintain until it's time for a bearing replacement. The cranksets and bearings are the same for both systems. The difference is how the bearings fit the frame, and the size of the bottom bracket shell. PF30 systems seem to be a little easier on bearings due to the "plastic" bearing seats pressed into the frame. You'll know when it's replacement time. Spin the cranks when you pull the chain for maintenance. If it rumbles or doesn't spin smoothly, replace the bearings. Install a better bearing like an Abec5, using a good installation procedure and you're good to go. Until then just ride.

+1, nothing to maintain. Never Fix A Running Piece

Thanks, but my crank does not have an 8 mm fixing bolt, it is 10mm. The ring has holes for a pin spanner, not a 5/8ths. The linked to Park page on that thread is for GXP BB. I do not have that I have Pressfit 30.

scott s.
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Thanks. I have that already. The guide shows 5 variations of crankset. None of them are what I have. that's why I am asking. The closest seems to be the BB30. Should I assume that BB30 is the same as Pressfit 30 (there is a difference in the left crank from what is shown in the SRAM guide because my crank arm has a ring that is installed with a pin spanner).

scott s.
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In the past I've found it easier to clean chainrings by pulling the crank. At least I have had inner ring that wouldn't maneuver over the crank spider to get off. Understand that there isn't much to do with the BB itself. But I guess I would at least like to fully understand exactly what is on the bike, even if I don't remove it. I see many threads about which crank goes with which BB, adapters, preload, chainline/Q factor etc. Since this is my first foray into something other than English threaded BB shell, would like to know. I do have Zinn manual, along with Glenn and Bicycling Mag from years ago. Meanwhile it seems like there are many complaints of creaking (though I suppose a percentage of these are mis-identified).

scott s.
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The difference between PF30 and BB30 is the concern of the frame type, not the crankset. They use the same type of crankset. BB30 involves pressing the bearings directly into the frame, whereas in a PF30 frame, the opening is slighly larger, requiring a plastic sleeve to be installed between the bearing and the frame material. This accomplishes a few things. It allows for the plastic sleeve to take the wear, and then be replaced if necessary, instead of the frame itself wearing out leaving you out of luck. Secondly, the plastic buffer works nicely to silence the creaks that are more typical with BB30 bearings that have been pressed directly into the frame. Plastic is less likely to squeak, so the PF30 is potentially a quieter interface. Thirdly, manufacturers prefer to build bikes with PF30 because the tolerances are a bit bigger for a 'proper fit.' With a BB30 interface, the machining on the frame's BB needs to be PERFECT because the metal bearing needs to fit tight but not too tight, very little range of error before problems show up. But because the PF30 has a plastic sleeve, it's able to provide a secure fit in a wider range of spec error.... This means fewer framesets thrown out during the quality control stage.

-Jeremy

There are only two types of SRAM Force NDS crank arms -- the "regular" version (shown on the right side of the guide) and the "I-A" version with the shaft attached to the NDS arm (shown on the left side of the guide).

Is the "pin spanner" ring you're talking about actually the extractor bolt retainer? If so, don't mess with it. All you need to get the crank out is an allen wrench that fits the extractor bolt. Loosen the bolt and it should pull the crank arm off. Doesn't matter what kind of BB you have. If that's not making sense then you're probably going to have to post a photo so we can see what you're talking about.

Your crankset isn't a press fit if it is a Force, at least according to the Sram install sheet. I just changed out my 2013 Sram Apex for a 2013 Sram Force crankset, the Apex used the press fit the Force doesn't. The Apex comes off by loosening the 10mm hex on the drive side, the chain rings/crank arm come off along with a plastic (approx. 1/2") spacer, the NDS arm and shaft then pull out. On the NDS there is a tension adjuster. The Force installs from the dive side, opposite of the Apex, the Force uses shims and a wave washer to set the tension on the NDS.

Notice how the OP said he has the 10mm hex bolt?

And how in the PDF there's no road PF30?

It's the BB30 crankset, I bet. PF30 is just BB30 plus the plastic bits in a slightly larger bore.

http://bikeforums.net/attachment.php...hmentid=362772

This crappy board is shrinking the pics, dammit.

OK I've been doing a bunch more reading/searching. I think my main problem was looking too much at SRAM GXP cranks and confusing with BB30 cranks. (FWIW I don't think the SRAM website is that great in pointing out the difference). At any rate I couldn't find a reference there to my specific cranks:

Here is the NDS side crank:

http://i.imgur.com/PLSNxYR.jpg

But in the end I see the same exact bearings are used in the BB, 6808 30.0/42.0/7.0. The only difference is because of the plastic cups on the PF30-68, the overall assembled size (to the outside of the cups) is 71 but obviously the spacers / wavy washer only contact the bearing not the cups so that isn't an issue (as long as the spacers allow enough clearance for the cups).

Also I take it isn't possible to replace just the bearings in the cups, you need to replace both together? (Not looking to do this, just curious.)

Thanks again for the help.

scott s.
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