Wednesday, October 23, 2013

Press-Fit Bottom Brackets: The Creaking is Standard

One of my cycling friends recently got a new mountain bike. Carbon fiber wunderbike with one of the latest press-fit bottom bracket systems. Don't even ask what type of press-fit BB, because I don't think he knows, and I don't think I could tell the difference. Thing is, the bottom bracket creaks, and the shop mechanics seem unable to make the creaking go away. After asking around and doing a bit of reading on the subject, I'm finding that creaking is apparently the only thing that is actually "standard" about bottom brackets today.

It wasn't that long ago that there was a handful of national standards for bottom brackets, and though some would probably want to make it sound as if that was terribly confusing and problematic, in practice it was pretty easy to deal with. The most common was British/ISO. Most quality lightweight bicycles with threaded bottom brackets used it. Most Italian bikes used the Italian threading standard. There were also French and Swiss threading standards, and a couple of oddballs -- Raleigh, for instance, was a big enough company at its peak to have its own unique standard. Swiss was always rare, and both it and French threading disappeared by the 1980s along with the others, as most companies regardless of nationality adopted British/ISO. Only Italian bikes continued as a holdout, keeping Italian threading alive. But even when the various standards were in use (or when working on vintage bikes today) it wasn't hard to figure out what one was dealing with -- often just knowing when and where the bike was made was a huge clue. Taking a few simple measurements and looking closely at whether the threading was left- or right-handed generally confirmed it.

So, for the last 20 - 30 years, it seems bikes had finally arrived at one international standard (with just one nation holding out) for bottom brackets.

Today, it seems that there is a new bottom bracket standard every year. Try and keep them all straight. BB30; PF24; PF30; BB90; BB95; PF86; PF92; BBRight; and BB386. I may have left out a couple, and some of them may have different names depending on who makes them. What most of them have in common is that they have some type of press-fit bearings and require various adapter kits to make them work with different brands and types of cranks and axles. Some of them were created by frame or bike manufacturers, while others were devised by the component manufacturers. They all claim to be vast improvements over one another or over threaded bottom brackets.

What is the advantage to one of these new press-fit systems? As a rider/consumer, I don't believe there is one. Really. The manufacturers will claim the benefit is lower weight and greater stiffness, and people love to hear that, but the difference in weight is negligible -- anyone who can tell the difference in weight would also have to be able to feel the difference of a couple sips of water from their water bottle. As far as stiffness -- just how stiff does a bottom bracket have to be? Once the industry shifted away from square taper bottom brackets, it seems to me they got as stiff as anybody can possibly need. Again, the difference in stiffness between one of these new press-fit systems and an ISO threaded BB is just not something people are sensitive enough to feel.

So then what is the REAL advantage? Like a lot of bicycling "innovations" and "improvements" made in recent years, the advantage is mostly to the manufacturer, especially those working in carbon fiber. By switching to some type of press-fit BB, they can eliminate the metal sleeve in the bottom bracket shell, eliminate the need to have it perfectly aligned and machined to the right tolerances, and eliminate the need to cut threads into it. Lennard Zinn, who in my observation seems to embrace a lot of new technology (or so it appears to me when I read his articles in VeloNews), had this to say in Velo Magazine's 2012 Buyers Guide: "The whole idea of press-fit bottom brackets, after all, is to fit into frames that are not made to exact tolerances so that they can be simply molded with cheap labor and not machined afterward. Now you see the problem."
A press fit BB adapter

The DISadvantages to the consumer are plenty. Changing or replacing components, particularly cranks and bearings, becomes more complicated as installing the proper adapter becomes necessary. The design and quality of those adapters varies by manufacturer, and getting them to fit properly into the frame, and the crank and bearing assemblies to fit properly into the adapter are also issues. Poor fit is not uncommon, and creaking is the usual result. I have yet to talk to a mechanic who hasn't had issues with them. Again, Lennard Zinn: "With the upside of increased frame stiffness claims, that are largely correct, comes a mechanic's nightmare. . . Complaints about creaking or dislodged bearings are common after a frame is replaced with one that has a different BB shell standard than the original. . . but many times the adapters creak or work their way out of the frame. The solution to this creaking? In many cases, frame or crank manufacturers suggest using Loctite. Clearly this is a flaw in the design of the system if that's the fix."

BikeSnobNYC addresses his own experience/issues with a press-fit BB (Here, and Here). His description is funny, but also reflects a common frustration with these things. Here's a sample:
"I recently overhauled the bike, and it was time to pull the bottom bracket since the bottom bracket shell was full of all kinds of disgusting scum and frumunda which is something that happens to bikes. Naturally, the bottom bracket adapter was not supposed to be reused because it was plastic and this is the bike industry, so I replaced it with one made from metal that seemed like it would be a lot more better. And I rode. And I rode. The new bottom bracket adapter thingy was not more better. The crank kind of wiggled in there no matter what I did. So I called the company that makes the bottom bracket adapter thingy because they're the kind of company you can just call and be like, 'Hey duders, like, my bottom bracket's got like all this play in it and I'm totally bummed because it's not epic.' That's what I did, and the company was all like, 'Oh, yeah, duder, we know what that is,' and they sent me these new bearing cover thingies to put in the bottom bracket adapter thingy, and I put them in, but the crank was still all wiggly in there anyway."

The blogger and bicycle mechanic RogueMechanic doesn't pull punches when it comes to flawed or problematic bikes and components. He has stoked the ire of many in the bicycle world by blogging about engineering problems, poor construction, or flawed manufacturing -- problems that some out there would rather not hear about. Seriously -- the guy gets hate mail. He did some work for me on a completely different bottom bracket issue (or non-issue, depending on whom you listen to) with a Campagnolo UltraTorque crank system (that could be another whole post, believe me -- if you google "Campy Ultra Torque Problems" you'll find a lot of info on it, much of it from RogueMechanic). I'll never forget what he told me when he returned my repaired bike -- if you've got a bike with a threaded bottom bracket, "hold on to it" he said. Despite the problem with the UltraTorque, ultimately he was able to come up with a solid solution to it and it's been working beautifully ever since. Keep in mind, the UltraTorque crank system is designed for an ISO threaded bottom bracket. Problems he has seen with some of the press-fit systems are much more difficult to solve. Check out one of his articles about the BBRight system (Cervelo BBRight Problem and Solution).

Campy UltraTorque cups being installed
in a British/ISO threaded shell.
Why haven't the various manufacturers simply adopted one new standard? Competition is one reason, I suppose. One frame/bike company comes up with a new standard and releases to the public. But a competing company isn't likely to want to adopt it and seem to be supporting their competitor. Also, each new system supposedly addresses the perceived problems or weaknesses of the other systems, trying to out-do one another -- though not without having other weaknesses themselves. And with so many competing "standards" (that word is rapidly losing meaning) the only solution for any kind of compatibility is the use of adapters which lead to fit issues and creaking.

It's possible that at some point, the "market" will narrow down the choices. Maybe if we're lucky the manufacturers will stop coming up with new systems long enough for that to happen, and one system will emerge as the winner. It might not even be the best in every way, but it will at least be an actual "standard" in the true meaning of the word, then companies can actually make compatible parts that properly fit together. I can't help but think back to VHS and Beta home video systems. Anyone still have a Beta machine out there? If that's too far back to remember, how about BlueRay vs. HD-DVD? For a while, those two duked it out in the high-def video disc market, but eventually BlueRay won out. We can only hope the same thing happens here.

Addendum: So what is a person with a vintage frame to do if they need a new bottom bracket and they have one of the old, now-defunct threaded frames? Velo-Orange offers their sealed cartridge bearing bottom brackets in French threading, which is one of the more common of the obsolete standards. They also have an internally-expanding "threadless" bottom bracket that they claim works well in frames with damaged threading, and should also will work in some older Raleighs and frames with Swiss threading, but I've never tried or tested them. Phil Wood bottom brackets, which are about as good as one can find, are available for French, Swiss, and some older Raleighs and even Chater Lea threading which is yet another old oddball. Lastly, there's always eBay.


  1. Brooks, threaded bottom brackets are still widely available, from cheap Shimano UN series to their better ones, to SKF (as well as Phil Wood, whom you mentioned) at the high end. Given the millions or billions of threaded frames out in the world (and still many being sold new, from low end department stores to mid range Surlys and Soma to high end customs, plus the innumerable bikes sold outside of the US) I don't think they'll disappear anytime soon.

    I'm enjoying the blog -- nicely done! Thanks! -Julian.

    1. Hi Julian -- thanks for writing -- actually, I didn't intend to make it sound like threaded BBs were going away. The main point I wanted to get across was simply that "new" is not always "better." Given a choice between a new bike with a threaded BB and one of the new press-fit units, I'll take threaded. Easy choice.

  2. "if you've got a bike with a threaded bottom bracket, 'hold on to it'"

    As long as it is English or Italian, you're fine. I do like the external cup "Hollowtech" BBs though. You can get excellent replacement (cartridge) bearings for $5 if you buy from a bearing supplier and not through bike channels.

    No doubt you have comments about the wonders (not) of the integrated/tapered headset elsewhere?

    1. Even a French threaded bottom bracket is pretty workable -- as there are some options. Velo-Orange offers some French threaded BBs, and at the high-end, Phil Wood has always made mounting rings for French threading. The external cup BBs are fine -- threaded into a BSC shell, they are secure and should be "creak-free." I have the external cup "Ultra Torque" BB from Campy on a bike, and apart from some solvable engineering issues (namely, using shims instead of the "wave washer" that Campy supplies in order to properly set the bearing pre-load), it seems to work well.

  3. So could a press-fit BB be replaced with a threaded BB? Is it even worth replacing?

    1. Do they make adapters to use a threaded BB on a press-fit frame? I suppose somebody probably does. But the creaking comes from the interface between the adapters and the frame which may not be made to exactly-matching tolerances -- so if it creaks, a threaded BB adapter may not fix the problem.

  4. Came across this topic,

    In my case, Green Loctite did solve the problem for me in various cases

    Just put some green loctite between the adapter and the frame.

    Only problem is if u use BB30 or an other fame / crank combination were you only use bearings instead of an adapter. In this case you need to put some loctite on the outside of the bearings and let it dry out a little. Press the bearing in and take care that the green loctite wont get inside the bearing.

    So far, Best standard seems PF30, Basically because it has a high diameter and is small so you can fit every crankset you wan't (all with different adapters from different brands, but they are out there). And secondly, You always use some sort of cups, so you don't need to worry for loctite to get into your bearings and can use a whole lot so you are sure it will solve the creaking.

    However, So far green loctite has been my friend and i have had no creaking with it so far.

  5. Phil Wood made a French outboard BB for me and it has worked very well. It fit my Shimano Hollowtech crank easily. As the French style is of limited demand, Phil Wood seems to about discontinue the line. If it had not been for finding that component, my rebuild of a Mondia 1976 frame would have been sidelined a bit. Was wondering about a press fit into a French threaded hanger but with the creak problem, probably would be careful on this. Good to know about Velo Orange still making French BB.

  6. I also have bb woes, a brand new carbon fibre Road bike that starts moaning when it's warm and the gradient gets above 5%

    I called into myLBS (where I bought the bike from) and the mechanic said it definitely not the bb! His take on it was that modern carbon frames are so solid that all the torque gets transferred to the back wheel. He said the issue was that the relatively weak rear spindle (that is hollow due the the quick release) moves about and that causes the squeak. He popped the bearings out on both wheels and really greased them. I took it out on a 100 mile ride yesterday, it was fairly warm and the ride had a couple of 10% rides. Guess what? Not a single squeak or clunk!