Allytech

Is it V-Brake or U-Brake what do you think

Rolla

Given your previous posts about a BMX bike, I'm gong to guess U-brake. What do I win?

base2 

"V" brakes were the replacement for canti's on canti studs that pulled 2x as much cable 1/2 as hard to avoid compression of coiled brake housing.

"U" brakes were the BMX equivalent but the studs were mounted further away from the wheel axle and were operated via a long "U" shaped center-pull style straddle cable.

Both are considered "long pull" so you will need matching brake levers or if have an option set the levers set to "long." Meaning the cable head attaches at the location further from the brake lever pivot.

Rolla

U-brakes are often run underneath the seatstays, or sometimes under the chainstays behind the bottom bracket. V-brakes are always on the top of the seatstays.

chaadster

For clarity, U-brakes debuted on MTB bikes— well before they appeared on BMX— as the high performance brake option of the ‘80s to replace weak and clearance-challenged cantilever brakes. The V-brake came after the U-brake as the high performance option, and effectively replaced U-brakes.

Also, the U-brake takes its name from the shape of the brake arms, not the straddle cable, and in fact, U-brakes needn’t even use a straddle cable, as some models can run the cable housing right to one of the arms directly..

The U-brake was, as I recall, Shimano’s high volume interpretation of Charlie Cunningham’s roller cam brake.

cxwrench

Another senseless, detail free post.

base2 

Thanks for the clarification. Your way makes more sense.

dedhed

mountain bike u brakes were short lived - a couple, two, three years in the late 80's. They filled with mud/debris due to location.

​​​​​​https://velobase.com/ViewComponent.a...1bb58&Enum=117

alcjphil

No photo, no opinion

sweeks

And usually in front of the fork... but not always!


Front brake behind the fork. IMO, this makes adjusting the brake shoes a bit more difficult.

veganbikes

Also lets keep in mind that V-Brakes are a trademark from Shimano. Linear pull brakes would be the proper name for non-shimano brakes of that style.

However yes nonsense post for no reason.

Rolla

I had a 1992 Grove Innovations X-frame that had an under-chainstay U-brake. With a seatstay mounted brake, heel strike would have been an issue.

chaadster

It wasn’t really the location that was the problem— you could find MTBs both with under-chainstay and typical seatstay mounted U-brakes— but rather due to the nature of the design, which restricted wheel clearance and caused mud to build up. They were also heavy because of the design.

The response was to develop low-profile cantis, designs which evolved into the V-brake.

redcon1

Not accurate as far as the timing. Cantilever brakes were around well before (and during and after) MTB U-brakes were designed. The primary reason for U-brake development was the relatively poor performance of cantis. Leverage was much higher with the U-brake but as noted, they quickly mucked up in muddy conditions, and they were heavy-- so everyone went back to Cantis rather quickly. Circa 86 I had an MTB with the under-chainstay Shimano Deore U-brake (Cantis on front) and in non-muddy conditions the power and better modulation of the U-brake was definitely an advantage IMO. In muddy conditions I just left that bike at home and took my other bike with the standard-of-the-time Cantilevers.

chaadster

Note that I said “low profile” cantis followed the U-brake.

Similarly, discs followed V’s, which is not to say that discs didn’t exist before nor that V’s disappeared after, I’m talking about trends and common usage. Suntour didn’t eliminate the rollercam from it’s lineup until after they launched the lo-pro XC 9000 series cantis, nor did Shimano drop the U until after the ‘92 intro of XTR and the lo-pro canti.

redcon1

I did note that.. I just don't put the low-profile arms in their own category, I suppose. The braking performance of the low-pro versions were at best the same-- and with poor setup, even worse than the medium or longer arm canti's. I suppose most everyone, including me, moved quickly to V-brakes, and were elated when disc brakes came along

Edit - I see the first Shimano V-brakes weren't available until 1996 - that was a lot of years of canti-s and u-brakes. I guess the developments in forks and suspension were dominating all my memories of those interim years.

Shimano History (mombatbicycles.com)

c_m_shooter

U brakes were popular for like 2 years, the odds of finding a bike with them is low. V brakes were popular for a long time and work great.

ClydeClydeson

This does not agree with my experience. U brakes were put on bikes before 'long pull' levers were available. Long pull levers weren't a thing, AFAIK, until Mid 90s when V brakes came out. All bikes with U brakes came with the standard 'short pull' levers of the time. There were also brakes very similar to 'u brakes' that were common on old road bikes - 'centre pull caliper brakes' and I think these had very similar geometry to the U brakes, which were typically mounted on posts above the rim... these were used with standard road levers which are definitely 'short pull'

Rolla

U-brakes are still popular and very much in use on BMX bikes, which the OP's other threads indicate he is riding.

ofajen

Also my experience. I have one of those late 80s MTBs with a rear U-brake. I have used it both with vintage road levers and with standard flat bar levers and it works properly with those levers which are now called “short pull”.

Otto

ClydeClydeson

When I initially read base2 's post, I thought maybe I was wrong, and maybe long pull levers would have worked better, but, as I recall, U brakes with short pull levers were very crisp and firm feeling, nothing like the unacceptable mushiness that V- or other long-pull-brakes feel like when used with short-pull levers. I am quite certain they are mistaken, or misspoke.

chaadster

Not just cantis and U’s, but as I mentioned earlier, roller cam brakes too, which were the design precedent Shimano created the U-brake from.

Charlie Cunningham invented the roller cam and sold it through WTB, later licensing it Suntour in ‘85. Shimano couldn’t directly copy Suntour’s brake, so they came up with the U-brake as the workaround to bring a competitor into that space. So really, Us and roller cams should be considered together, and enjoyed a good 10 years of usage on some of the most interesting, creative, and important framesets dating back the early days of MTB.

base2 

Well, everyone has a time to eat a big ol' bowl of crow.

I think today is my day. All this time I thought U's (& BMX calipers) were long pull & just accepted things it as-is.

Time to onboard some knowledge in this here noggin' o' mine.

Thanks all.

79pmooney

Let's get down to the root of all this. "V"s and "U"s. If you double up a "V" you get two double "U"s as in "W", not double "V". Spelled out clearly in out alphabet. I rest my case.