Hi All!
Between you, Andy and Martin have done a great job describing interrupter/-cross-top levers!
They are indeed called "interrupter" levers because they install midway in a cable run and so interrupt the smooth course of the cable
housing (the
cable remains intact throughout). What many don't realize, however, is they do *not* pull any cable. Instead, they work by "shortening" the cable housing on which they press. This has a unique effect, in a rider cannot operate the conventional levers and interrupter levers at once -- only alternately. This is not a problem in practice, but it always astonished me and is a fun if simple way to dispel boredom whenever I rediscover it on a really long stretch of riding (Ah! The simple pleasures in life...made possible by an empty mind and boredom
). They are also called "cross-top" levers from their early popularity in cyclo-cross use. It is an ideal place to put the elastic brake loops if one uses a Click-Stand; they're handy to reach, right up-top and quick to set and release as well. Just be aware you cannot also set elastic loops on the regular levers at the same time, or you'll get a push-me/pull-you-effect.
For me, interrupter levers provide continuous opportunities to apply the brakes no matter where I am riding on my drop handlebars. I realized some time ago life could be easier when going down steep downhills if only I could get my weight significantly further back while still braking. Holding onto the ends of the drops didn't do it, but the interrupter levers did the job nicely. They are amazingly light (a fraction the weight of a standard lever and should come with a warning as to their addictive properties. Once in use for certain types of riding, it is hard to give them up or imagine cycling without them, and they actually encourage changing hand positions to a degree I could not have imagined before getting them.
Really, if one is running drops and v-brakes, there is only one choice in two flavors for brake and interrupter levers. Tektro and Cane Creek. These two products are essentially identical except for color choice and brake hood design/color (the Cane Creeks have little salamanders on them and are a little softer/gummier but rougher, and parts are interchangeable between the two). Most of the competition is geared toward use with cantilever brakes, which require a different amount of cable pull (and have different leverage due to pivot placement) and will bottom-out when used with v-brakes.
I've got to say, interrupter levers couldn't be simpler -- and are almost disappointingly simple! There is play in the levers and the bearings are nothing to write home about. And...it doesn't matter a whit. They are reliable, simple (as a virtue rather than a detriment), and provide reliable *full-power* braking at will.
There's a couple important things about setup...
1) You *have* to get the interrupter levers that match the cable pull required by your brakes. That means v-brake and cantilever -compatible levers are not interchangeable. They appear identical, so read the product description and model numbers carefully before ordering, or the result will be disappointing/unusable.
2) Most dealers don't get the angle right when fitting them for sale. They are not intended to go straight ahead of the bike, but rather inline with the angle of one's arms and hands for easy application. If you ride with elbows bent for shock-absorption, then they will need to be angled slightly higher, but not horizontal, as on some recent installations I've seen on dealer floors. Martin got his just right, and so did I, with variations for our physiognomy and riding styles. Of course, individual preference will differ, so they can be placed however suits!
3) You *have* to purchase interrupter levers with a clamp diameter appropriate to their placement on the 'bars. In my recent handlebar change, I might well have gone for 31.8 clamp size, but I could not get v-brake compatible interrupter levers for placement on that larger stem-clamp area. The smaller-diameter levers wouldn't have worked, 'cos the transition from the large center bulge to the smaller 'bar diameter placed them too far outboard. I have mine mounted right where the 'bars begin to swell toward the center clamp diameter. And, yes, the same interrupter levers have enough leeway in clamping to accommodate 25.4mm or 26.0mm or 31.8mm bars 'cos the *bar* diameter is the same on all; it is the center bulge or sleeve that differs. By the way, interrupter levers won't fit the smaller diameter of MTB straight or comfort 'bars without shimming, so keep that in mind. They also will only rarely fit on bar-ends for the same reason (too-small diameter for their clamps).
4) Width issues. Because the interrupter levers need to fit snugly up against the 'bar's clamp bulge or sleeve, they extend outward from there. I have narrow hands and skinny, bony fingers, and couldn't use them comfortably with my Nitto Randonneur handlebars, which are 45cm at the ends, but only 37cm at the brake hoods. I tried them on a set of 42cm Maes-bend (traditional) drops, and found things a but tight -- my hands kept being forced into the bend of the upper run of handlebars and my wrists twisted. On my 44cm Bontrager Maes bend or the 44cm Zoom anatomics (as fitted by Thorn), they are "just right" and I can brake comfortably from pretty much anywhere I would have my hands atop the handlebars. Hint: Every interrupter lever I know of with a 31.8mm clamp diameter intended for fitting to the larger bulged area is also intended only for use with cantilevers, not v-brakes.
5) For maximum smoothness, one really should (almost a "must") install housing ferrules to keep cable operation smooth. Because the cable housing is um, "interrupted", a clean entry and exit is necessary to prevent binding. It isn't a big deal to get right, but ferrules make the operation sort of self-policing and much quicker and easier. Of course, it is also a good idea to tape the cable housings in place with electrical tape before the final padding/taping of the handlebars. This prevents shifting of the cable housings and makes for a much quicker neater job at installation and in future re-tapings.
That's pretty much it as far as cautions and tips go. These things have made a positive difference in my use, and -- especially with wide drops -- give me many of the advantages of straight handlebars on a drop-'bar bike. I like them very much.
Xerobike, you asked...
Why dont people use extension levers on drop bars anymore?
Ah! The answer is...many were never very safe! The design was generally poorly executed and resulted in the "safety levers" (as they were called on this side of the Pond) bottoming-out long before safe levels of braking could be effected. The basic idea was good and so were a few of the designs; the
general execution of a majority of these levers was poor, and thankfully they went the way of such things. In his Glossary of Cycling Terms (
http://sheldonbrown.com/gloss_e-f.html ), Sheldon Brown had this to say in amplification:
Extension levers
In the early 1970s, many people bought bicycles with drop handlebars, for reasons of fashion, even though drop bars did not suit their casual riding style. Given the frame and stem designs commonly available at the time, it was generally impossible to get drop handlebars high enough up to allow a low-intensity rider to reach the drops comfortably.
The problem was worse for many women, whose shorter torso made it hard to reach forward to the drops. Though a taller handlebar stem with less forward reach might be installed, this often did not occur. Also, small hands could not comfortably grasp typical drop-bar brake levers of that time.
Dia Compe invented bolt-on extensions that allowed Weinmann-type brake levers to be operated from the tops and middle of the handlebars, making this type of bar bearable for casual cyclists, since they never had to use the drops. This was so popular that Weinmann traded licensing with Dia Compe, so that each could copy the other's products.
(Stem shifters were also popularized around the same time, and for the same reason.)
This system has several drawbacks:
The extension lever partially applied the main brake lever, reducing the available lever travel. Not all brands/models suffered from this, but the most common ones did.
The attachment hardware precluded the use of the top of the brake lever hood as a comfortable riding position.
They encouraged the practice of riding with the hands on the top, middle section of the bar, which is a position that doesn't give very secure control, especially on bumpy surfaces, because the hands are too close together.
The hardware that held the extension levers to the main levers was prone to fall off.
Other manufacturers produced similar systems, some of which addressed some of these difficulties.
Extension levers are sometimes known as "safety levers." Since many people believe they actually reduce safety, the slang terms "death grips", "suicide levers" and "turkey wings" are occasionally substituted.
In the early 21st century, a greatly improved system of "interrupter brake levers " appeared, with all of the advantages and none of the drawbacks of the older extension levers. These also have the advantage of being compatible with modern "æro" brake levers which work a lot better than the older style levers that had the cables coming out of the tops.
Interrupter levers aren't for everyone, every style of bike (I can't see using them with my rando-bend 'bars or on the tandem), or every use (probably not appropriate in the peloton or while riding a tight, fast criterium), but they are another useful option for those who want them, do no harm, and open a lot of possibilities for additional fatigue-relieving changes in hand position and allow full-power braking from anywhere when using drop handlebars. They're tailor-make for steep decents and tired, achey hands on long rides that require a lot of braking.
Hope this helps.
All the best,
Dan. (...who has no halting concerns about these levers)
