Tuesday, May 5, 2020

Retrogrouch Tool Time: Crank Bolt Tools

If you spend much time doing your own bike maintenance, eventually you end up with a pretty nice assortment of bicycle-specific tools. And one thing I've found about vintage bike nuts (myself included) is that many of us are just as nuts about bicycle tools as we are about the bikes themselves.

Now that I've gotten my workspace all cleaned up and organized, I thought it might be worthwhile to talk about some of the tools in my collection. And with that in mind, I figured I'd start with a fun one -- the crank bolt wrench, sometimes known as the "peanut butter wrench."

From top to bottom: Park 16mm, Park 14mm, Campagnolo 15mm, another Campagnolo, and T.A. 15.

Legend has it that they got their culinary nickname because racers during multi-day races would sometimes improvise meals, and the shape of the handle made it useful for spreading peanut butter. I honestly don't know if anyone ever actually used one for that purpose, or if it's just a myth. If anyone is willing to admit that they have actually spread peanut butter with their "peanut butter wrench" I'd love to hear from them.

Oftentimes, a person only needs one of these, and 15mm is probably the most common. And that size is also useful for the axle nuts on most track bikes. But now and then you might find a crank attached with 14 mm nuts (typically on cheaper bikes with a solid bottom bracket spindle), so I like having that one available. The 16mm size is a real oddball. It is most often found on old Zeus cranks, which are seldom seen these days. I would like to have an actual Zeus wrench (for nothing but "emotional" reasons), but those are awfully rare, and they tend to sell for a premium when they come up on eBay. The Park one isn't all that common these days, either, to tell the truth. I've only encountered the 16mm crank bolts once in all the bikes I've worked on over the years, but I'm glad I have the right wrench.
Sometimes a standard socket just won't fit in the gap.

OK - so if someone has a full metric socket wrench set, why do they need a special crank bolt wrench? Well - the gap between the bolt head and the recess in the crank itself can be pretty narrow - and the "walls" of many sockets are often too thick to fit in the gap (and this is especially true with the 16mm size). Sometimes people will improvise by taking a standard socket and grinding it down to fit, but that's an unsatisfactory solution to a tool lover.

In my own collection, I have two of the Campagnolo wrenches. One is quite a bit older than the other. There is a difference between them visually -- the older one (the upper one in the picture above) has a "pebbly" texture in the background behind the name. I got that one from an old bike shop many years ago and it probably dates to the 1970s. The other one probably dates to the 1990s or early 2000s and has more like a "cross-hatch" pattern behind the name. I have two because sometimes I pack one of them with me on rides with my fixed-gear bikes in case I need to remove a wheel. The T.A. one is perhaps a bit superfluous, so I suppose I have it because . . . "collecting."

To go along with the crank bolt wrenches, I have a couple other items to show:

A pair of Campagnolo crank pullers. The part that threads into the crank is 22mm, which is the standard for most square-taper cranks, so it gets a lot of use. Some older T.A. cranks used 23mm, and some older Stronglight cranks used 23.35 (which was just an evil thing to do). OK - so why do I have two of these? One is normal "right-hand" threaded - which is the most common. The other is "left-hand" threaded, and is only used on cranks that have a "one-key" allen bolt release system, such as the '80s vintage Campagnolo C-Record. If for some reason the "one-key" system fails, it is possible to remove that from the crank, and install this tool to remove the crank from the bottom bracket spindle. It's quirky.

Though the regular right-hand puller above works on most cranks, I do have a Park branded one (not shown) that will work on the 23mm T.A. cranks. I don't currently have the 23.35 Stronglight puller, and so far have not needed one. It's important to mention that a lot of old Stronglight cranks have been damaged because people used the wrong puller. A 23mm puller will seem to thread in well enough to fool a person into thinking it's fully engaged - but when they start applying the pressure needed to remove the crank, the threads get stripped out. OUCH!.

And I also have this:

This is a Campagnolo adapter and 7mm allen wrench - meant to be paired with the 15mm wrench shown above. I just mentioned previously that Campagnolo cranks in the 80s had a "one-key" release system. These consisted of a puller threaded into the crank (using left-hand threading), and then a 7mm allen wrench was all that was needed to remove the crank. But one can't always apply enough torque with a typical 7mm allen wrench to remove a crank. So that's where this thing comes into play.
It would go together something like this. It's possible I've put this together "backwards" somehow, but it doesn't seem to make a difference.
In practicality, though, I've found that this 7mm allen socket on a standard ⅜ inch socket driver works just as well, and requires no "assembly."
Tools like these aren't really needed much if all a person has are "modern" bikes. Many cranks today can be removed and installed with no more than an allen wrench. But if you work on vintage bikes, or if your cranks still attach to an old-style square-taper bottom bracket, they can be very useful. And having some variety means there are just that many more old bikes that you'll be able to work on.


  1. I think the goofy campy adapter thingy is supposed to a have a benefit that you may not have noticed. If the amount of 7 mm hex poking out is enough to seat all the way into the crank bolt, and no more, than the adapter face acts to stabilize (cantilver?) the hex shaft, so it's less likely to pull out (because you can't really exert force 100% around the thread axis... get it?). Anyway, I think the adapter is supposed to be in the PB wrench in the other direction, and with just the right amount of 7 mm poking out.

    1. The trick is finding a 7mm hex key. It's a fairly rare size. i once had a bikeshop mechanic tell me with a straight face that 7mm keys "didn't exist." (TBF, he was a young teenager.) At the time i needed it for an old 3TTT stem bolt. When i found a source i bought 3 (to replace the key i'd lost.)

  2. How on earth did Stronglight come up with 23.35mm? Oh, I'll bet they were looking for something that would convert handily to 32nds of an inch - you know, 29.42/32". I've never owned a bike with a Stronglight crank, but at least now I'll be forewarned if I'm ever tempted!

  3. A few years ago i briefly returned to track racing after a 20 year hiatus. One night in the infield, i needed to borrow a peanut butter wrench to tighten my rear wheel. My request drew blank looks from my 20-something neighbours.

    (someone had to translate & explain the name to them.)

    Good thing i didn't ask for a "pregnant wrench!"

  4. I've never seen a crank bolt other than 15mm. I didn't even know they existed, thinking naively, that SOMTHING in the bike world was standardized. I just use a 15mm socket, which is thin enough to fit.

  5. I have, and have used, every one of those tools! Okay, I think I may not have actually used the left-threaded Campy extractor, but there's one in the drawer, just in case. I also have a Zeus peanut butter wrench, which has more of a bend in the handle than Campy's, and thus it's less likely you'll bust your knuckles on the crankarm. Thankfully, I got over the "I have to have one of those tools, too" many years ago. The first cotterless crank I owned was the Stronglight 49D on my 1971 Motobecane. I felt the need to pull the crank and ground down a 16mm socket to get the bolt out, only to find that the arm was still held tightly by some mysterious force. With the bolt removed, I could see the square axle, but not the taper, so back in went the bolt and it was a 10-mile ride to the shop, where I was sold the extractor and some tips on its use. I still have it, and it was my second bike-specific tool, the first being an Atom freewheel extractor I needed for my Varsity.

    The 49D (first released in single chainring version in 1932) was the first aluminum cotterless crank to get any widespread use, and it was sold for over 30 years, essentially unchanged. The design lives on even today with variations from multiple companies. Perhaps Stronglight should get a pass on account of being the first, but that extractor truly was evil -- it failed by pretty much every measure. It was not only an oddball size, in an era when just being metric was odd enough for English-speaking countries, but it also had a very short thread, around 4 mm, when everyone else had at least 7 mm of engaged thread. The extractor also suffered from what I call "French fit," which led me to have several, since they all fit a little different, and I worked on quite a few French bikes. The VAR 22C and Stein pullers are expensive, but much better and cheaper than a new crankarm.