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I can easily find images of these different nipples on Google, and as far as I can tell pear nipples are used on road bikes (in general) and barrel nipples are used on MTBs (in general).

Barrel Nipple Barrel Nipple

Pear Nipple Pear Nipple

I'd like to understand more about them. Why have two designs evolved? Does one (for a given type of bike (or brake?)) offer advantages over the other? Or, is it all just "marketing"? Lastly, are there any other designs in common use?

Thanks.

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The barrel end has the advantage of being able to pivot in a U-shaped notch in the brake lever. Other shapes are used where this "advantage" is not of any utility. Typically brake cables will be delivered with different style "ends" on both ends, and you cut off the one you don't want. –  Daniel R Hicks Jul 20 at 21:36
    
Apparently Campagnolo brake cables use pear nipples, but in a slightly smaller size to Shimano/SRAM road brakes. So a Shimano brake cable won't work in a Campagnolo brake lever. –  vclaw Jul 20 at 22:07
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Campagnolo use different nipples in both brake AND shift cables! Smaller pears and thinner 'cylinders' –  Carel Jul 21 at 12:04

3 Answers 3

up vote 3 down vote accepted

Original MTB brake lever designs did not include a rotating barrel inside the lever to account for the change in angle as you apply the brake, so the wire end needed to be round to accommodate this.

Road bike brakes have had the interior rotating barrel for a very long time.

If the wire end does not rotate, the brake wire will be flexed in a "coat hanger" way and break in a relatively short time.

They are two different solutions to the same engineering problem.

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Thanks. When you say "a very long time", does this imply that if I were to look at a brake from, say, 50 years ago, that I would see a pear nipple? Off whatever kind of bike? –  PeteH Jul 21 at 20:43
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Well, I've got brake levers that are over 50 years old that use pear ends. It was certainly very common, but there are always exceptions. I think there are old examples of the MTB style as well, but I couldn't find any in a quick search. Maybe on Old English 3 speeds and similar bikes? –  Fred the Magic Wonder Dog Jul 21 at 22:41

As far as I have been able to tell, there is no difference in terms of functionality or practicality.

With many bicycle components, different manufacturers create their own standards purely to ensnare customers. All of the vintage brake levers I have seen use pear nipples, so I assume the barrel nipple came later, but I have no idea which manufacturer first designed a barrel-style lever.

Personally I just find it an unnecessary annoyance... you can't really say one is used for road bikes and the other for MTBs... the bar end levers on my road bikes take "MTB"-style barrel nipples. Plus I have an older MTB with V-brakes that's fitted with crosstop levers - those take pear nipples. It's just a chore having to double-check before you go and buy new cables.

Both kinds are trivial to install, and work just as well as each other once on the bike. Although one style may be more prone to mechanical failure than the other, I am sure that the points of failure for both are far beyond the serviceable life of the cable (i.e. it will have stretched, frayed, and rusted considerably by the time the nipple breaks off).

Thankfully I've never seen a third kind.

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Thanks but I'm not interested in installing them, I'm interested in learning why there has been an evolution into two different types. (well, presumably an evolution...) –  PeteH Jul 20 at 20:26
    
@PeteH - Be thankful there's not 12 different types. (In fact, don't talk to loud or Shimano will decree that all cables have to use a new style end.) –  Daniel R Hicks Jul 20 at 21:38
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Barrel nipples have their origin in the world of motorcycling. Check on motorcycles from the pre-hydraulic lever age. –  Carel Jul 21 at 11:58

It is the design of components that determine which cable end is used. For somethings change comes slowly. My guess is that at some point in time someone wanted a lighter more compact cable end and designed what is currently called a road style end. That has become the standard. It would most likely work on a mountain lever that was designed to accept that style end. To my knowledge no one makes them. It is similar to the presta , Schrader issue. Presta valves were designed to allow rims that were thinner than was possible with a larger Schrader valve. While some mountain bikes are equipped with Presta valves but most mountain bikes still come with Schrader valves.

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Actually I think the MTB-style cable nipple came afterwards. I have many brake levers from the 1950s that are all designed for the smaller (by ~0.5mm), lighter (by ~0.125g), road-style nipple. –  headeronly Jul 20 at 20:33

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