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Technical FAQ: A history lesson on pedal threads; quick-link query

Dear Lennard
I just read your answer to a reader’s question about quick links. In your answer, you wrote that you used one link for several chains until it broke. That must have been quite a few openings and closing of that quick link.

My question is this: Most manufacturers of quick links say that their links are a one-time use only. If you open the quick link, you should replace it with a new one. Much the same as the manufacturers’ directive when using pins to close a chain.

Is that their lawyers and or accountants talking, or is there some reason why they are only “single use.” From what you wrote, you do not adhere to that schedule.
— Steve

Dear Steve,
Well, I imagine that it is their lawyers talking, but I have no proof of that.

Quick links for wider chains, pre-10-speed, always were multi-use, as far as I know. Maybe I just assumed that. My understanding was that the whole purpose for having the quick link was so that you could open the chain, clean it, and put it back together (using the same quick link).

SRAM was the first chain brand I ever noticed to state, starting with its 10-speed chains, that the master link was not to be opened. Period. I remember being aghast when I read that and then had it confirmed by SRAM employees with a straight face. The link went from being called a SRAM PowerLink for 8-speed and 9-speed chains to a SRAM PowerLock link for 10-speed, 11-speed and 12-speed chains.

Around the same time the PowerLock was introduced, I became aware of this wonderful tool from Park Tool, which made it easy to open those links, although you can still do it easily enough with a pair of pliers. Even better, you can open them with these cool Tire Pliers on the trail, which are super-tough tire levers that link together to double as master-link pliers. Tire Pliers are now part of my on-trail kit; I have opened the super-narrow, curved, SRAM Eagle PowerLock 12-speed “FlowLinks” as well as 11-speed PowerLock links with it.

I have opened and reused SRAM 10-speed and 11-speed PowerLock master links a number of times without incident (just on my own personal bikes, mind you; don’t interpret this as that I’m advocating it). Unlike in the case I talked about last week of having had a quick link break, however, I only use a quick link with the original chain I started it with. When that chain is worn out, I replace both the chain and the quick link with new ones.
― Lennard

Feedback on pedal threading direction

Dear Lennard,
In this day and age of opinion over data, I thought I would add some data to the pedal thread history question. I own a circa 1887 Rudge 53″ highwheel. Its pedals are through-bolted to a slotted crank arm and are both the same thread. Since neither the seat nor handlebars could be height adjusted, the only way to fit a rider of a slightly different size was to move the pedals within the 2″ slot. I have seen many other highwheels and to my recollection, they all have slotted cranks, but I may be wrong there. (I’ve ridden the highwheel bicycle pictured below on two centuries and will ride my fourth metric century in a few weeks at the annual Ride 4 Roswell fund raiser here in the Buffalo, NY area. Roswell Park is our local cancer hospital.)

Penny Farthing

I also own a circa 1900 Pierce chain-less drive bicycle, which I just restored to rideable condition. The pedal threads in the crank arms are in fact R- and L-threaded but, since the crank arms fit on either side of this bike, I only recently discovered that I had installed them on the wrong sides. (I had kept track of which side they came off of, so I can’t take all the blame.) The “set” of all metal pedals I had were both in fact lefts and are unmarked as to their threading. I had a more modern rubber block pedal which, fortunately was a right and was marked R. Thus I was able to switch and correctly install the crank arms with a mismatched, but functional pedal set. This bike is an amazing work of engineering. If you look closely at the full bike photo, you may be able to tell that it is a full suspension bike with a coaster brake. It has a wishbone seat stay, spring suspension and a leaf front fork. I rebuilt the wheels with NOS wooden rims and mounted remanufactured tubular tires to the 28″ wheels. I have not restored the saddle so the Cervelo is a tad out of place.

Safety bicycle

While I can’t answer the pedal thread question, I can say that the pedal thread issue probably goes back to the late 1880s with the invention of the safety bicycle and not earlier with the highwheel. I suspect the pedal thread design answer is buried in the patents of that period. (Bicycle design and invention was the dominant new technology of that era, such that 40% of all U.S. patents were for bicycles, and the patent office had a separate department just to accommodate them.)

Pennyfarthing pedal

Safety bicycle pedal

I offer one other comment about pedal threads. Many years ago, during my cross-country bike ride, I had a pedal lock up and contrary to popular theory, the pedal did not readily unthread. I had to stop pedaling and complete a road repair to continue.

This year, 2017, is the 200th anniversary of the Draisienne, which is considered the first bicycle. It is also the 50th anniversary of the founding of The Wheelmen antique bicycle club (www.thewheelmen.org). The club members collect, restore and ride bicycles older than 1939. We will hold our annual meet in the Philly area in late June. All are welcome to our public riding demonstration on Saturday, July 1; see the website for details.
— Ron

Dear Ron,
That is great stuff. That is a very good point, about the adjustable-length cranks. I’ve seen a lot of penny farthings with those. I’ve seen some without, too; no idea what direction these pedals are threaded, though.

However, left-hand pedal threads may not be buried in documents from the bicycle section of the patent office from back in the day. As you can see from the below, letter the Wright Brothers may have come up with the left/right threading design and may not have patented it. I received many letters pointing out this contribution of the fathers of flight; thanks to all of you who wrote in about this.

On your cross-country ride, did you have clip-in pedals or toe clips? Or was that a flat pedal that didn’t unscrew on you?

Your full-suspension, shaft-drive bike is very cool.
― Lennard

Dear Lennard,
Just to add a bit more chatter to the pedal threading discussion. The Wright Brothers, in their pre-flight bicycle shop days, claim the invention of the left hand threaded left pedal. From the Wright Brothers Museum, “In 1900, the Wrights announced a “bicycle pedal that can’t come unscrewed.” Pedals were mounted to the crank by threaded posts. On early bicycles, both posts had standard right-hand threads. As the cyclist pedaled, the action tended to tighten one pedal and loosen the other, with the result that one pedal kept dropping off the bike. Wilbur and Orville used right-hand threads on one pedal post and left-hand threads on the other so the pedaling action tended to tighten both pedals.”

You can also find this information on their Wikipedia entry and elsewhere on the Internet.

— Mark

Dear Mark,
Thank you and everyone else who wrote in about this. I did not know this piece of Wright Brothers’ history.
― Lennard

Dear Lennard,
So I actually pedaled my pedal right off back in November after it seized up. It was a 3-year-old Speedplay Zero that just froze completely. It happened about a block from home on the way out, so I was super-confused and figured the pedal was just loose so I went back to grab my big Allen wrench and tighten it back on (it’s a special large one I use for pedals for leverage). I cinched it up as tight as I could and then pedaled it right off within a block again. Something had to give, and it was the threads. That’s when I found out that the pedal had seized, thanked my lucky stars it had unscrewed itself, and went home to put on my spare set of Eggbeaters instead. It was a lifesaver in that instance, and it unscrewed itself from fully tight in about 10 pedal strokes.
— Luke

Dear Lennard,
Whoa. A reader’s skepticism that one could unscrew a seized pedal just by riding took me by surprise. Wouldn’t your calf act like an exceptionally long wrench handle? AND, since your body weight is behind it, wouldn’t you be putting a LOT more force on those pedal threads than most people could manually apply, even with a torque bar?
— Mark

Dear Mark,
Yes, if the pedal is rigidly attached to the shoe (not a flat pedal), I believe so. I think Luke just answered any of our questions about that!
― Lennard

Dear Lennard,
In the 16 May edition of VN Technical FAQs, Theo asks, “Why are the left and right pedal attachment thread directions not swapped?”

My answer to this is quite simple. It the bearings start to fail (which is the major reason why you would replace the pedal), it is easier to remove the pedal than would be the case if the pedal thread were reversed. If the pedal tightens as the pedal bearings fail, then with each pedal stroke the rider is unwittingly tightening the pedal to the point where they may be impossible or much more difficult to remove. Having the pedal threads as they are prevents this from occurring and ensures that the rider will proactively maintain the bearings in good shape, so as to avoid a situation where they might fall off. This includes, for example, your mention that metal bearings can even be replaced with plastic self-lubricating sleeves which never seize up.
— Marc

Dear Marc,
I love that theory! The Wright Brothers didn’t mention that as a reason for their invention!
― Lennard

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