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Technical FAQ: Shimano V-brake posts, hydraulic brake line quick disconnects

VeloNews tech expert answers questions about v-brakes and hydraulic brakes.

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Have a question for Lennard? Please email him at [email protected] to be included in Technical FAQ.

Dear Lennard,
I commonly come across confusion in various forums as well as product review pages regarding the fit of current production Shimano V-brakes on older posts. The newer style appears to be backward-compatible where the spring anchor sits securely even if there’s a slight gap, which gives an incorrect appearance and causes concern.

I believe this change happened in 2008 based on forum comments and a pre-2008 boss being available from Paragon. However, there doesn’t seem to be any published documentation on this change, and I was hoping you could shed some light on it; i.e., are the newer brake arms fully backward-compatible, and why did Shimano make this change? It would be nice to have your word to refer people to when they ask this question.
— Drew

Dear Drew,
Here is the answer from Shimano, via its communications agency:

“This is a really interesting question [for which] we had to ‘crank up the way-back machine.’ The short answer to all of this is that Shimano’s specifications for the brake post haven’t changed.

The area in question is the length of the section with wrench flats for tightening the post into the boss. Shimano’s specification is 5.3-5.7mm. It looks like the Paragon pre-2008 stud follows this spec. However, in 2008 and moving forward, Paragon reduced the length to 3/16” or 4.78mm.

Our thought is that in 2008, Shimano started making the spring cover shorter, and companies like the fine folks at Paragon realized they could make a cleaner look by reducing the length of the flats. Paragon likely has more info they can share regarding their change and can probably shed more light on the situation.
— Kristen Legan, Dispatch Colorado”

And here is the answer from the founder and owner of Paragon Machine Works:

“Shimano’s answer is interesting. I won’t make a change to manufacture and stock two different parts, and all the confusion it caused, for a ‘cleaner look.’ At the time, there was a problem with brakes fitting properly, and that’s what drove the change.
See the attached print. Based on the tolerances shown, this info probably came directly from Shimano. As I recall, new arms won’t work on old posts, but old arms do work on new posts. My memory is a bit fuzzy on that.
— Mark Norstad, Paragon Machine Works”

Well, Drew, this doesn’t clear up your question of, “why did Shimano make this change?” (especially since it says it didn’t make such a change at all). By “backward-compatible,” if you mean whether current Shimano V-brake calipers fit on old, pre-2008 Paragon brake posts, the answer is that the fit is not ideal. But post-2008 Paragon brake posts are backward-compatible with old Shimano V-brakes while also fitting current ones.
― Lennard

Formula hydraulic brake line quick disconnect.

Dear Lennard,
I recently made use of a couple of hydraulic brake line quick-disconnects and in doing my research before purchasing, I came across an old VeloNews post in which you lament there are no good options for hydraulic quick disconnects; I presume this was from some time ago.

I have several bikes, including a couple with S&S couplers for travel purposes. None of these have hydraulic brakes. Recently, I have acquired a new frame that I have built with hydraulic disc brakes. It is a gravel/all-road titanium frame built by a small company in upstate New York called No. 22 Cycles. This is also coupled, for travel. They use a variation on the Santana “z-couplers” design, which is built into the frame tubing. They offer a hydraulic quick disconnect they call the “Brake Break”. It looks like a slightly lighter-duty version of a hydraulic disconnect you’d find on a motorcycle. It fits inside the down tube, and one can access it when disassembling the frame for packing, in order to disconnect the rear brake.

I also came across the Formula Speedlock, which is a very svelte hydraulic brake line quick disconnect, even smaller than the Brake Break. Even if these leak a small amount of fluid, I would be OK re-bleeding the brakes every other trip…a small sacrifice for convenience. I have disconnected and reconnected these a few times, as a test, and the brakes seem to work fine. So, we’ll see how they do in actual travel.

Regarding the Formula Speedlock, as Dan Empfield states on SlowTwitch, the Italian company that makes them was probably caught a little off guard by the demand, related to the increasing use of hydraulic brakes on road, gravel, and TT bikes. Their distribution network in the states is very limited. I was able to order mine from a shop in Utah via eBay. In any case, they have a version that connects directly to levers/calipers for their brand of hydraulic MTB brakes, and they also have a version that can be used in-line on any brake. There is a Shimano/mineral-oil version and a SRAM/DOT-fluid version (different seals). I have attached some pictures of my own bike, on which I have the in-line version on my front brake line. This bike is a No. 22 Cycles Drifter titanium gravel bike, with frame couplers. On this bike, the rear brake runs internally, and on that line, I have a No. 22 “brake break” quick disconnect. The Brake Break is also a good option for hydraulic brake lines, but it is bulkier than the Speedlock solution. It is also more expensive than the Speedlock in-line quick disconnect. With the No. 22 device on my rear brake line, hidden in the downtube, and the Speedlock on the front, the whole package makes for a very neat, clean installation and a beautiful, coupled frame. I have only had it for about 3 weeks, but so far, no issues with either disconnect. Will they leak during air travel? I hope not. I think I will bleed the brakes a couple of days before I pack the bike on a plane, to avoid any expanding air bubbles in the low-pressure environment of an airline cargo hold.

Dear Scott,
Indeed, the Formula Speedlock is an elegant solution. Whenever customers order coupled travel bikes from me, I make sure they understand the extra hassles they are in for when using hydraulic disc brakes vs. rim brakes. While you would still need to remove the rotors for travel, at least with the Speedlock you can separate the brake calipers from the handlebar (like you already can separate the derailleurs from the handlebar with cable splitters, wireless SRAM eTap shifters, or unplugging electronic shifters), making packing in a compact travel case far easier.
― Lennard

Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder ( and purveyor of non-custom huge bikes (, a former U.S. national team rider, co-author of The Haywire Heart,” and author of many bicycle books including Zinn and the Art of Road Bike Maintenance,”DVD, as well as Zinn and the Art of Triathlon Bikesand Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.” He holds a bachelor’s in physics from Colorado College.

Follow @lennardzinn on Twitter.