Gravel on the Drop: Droppers from Crank Brothers and Shimano

I came of age when the Hite-Rite was the thing you added to your mountain bike to tell the world you were a badass descender. It was, in fact, not nearly as useful as it alleged. But the idea was as solid as a Parliament groove.

Twenty years after I pulled that Hite-Rite off my Merlin, the dropper post is as indispensable to mountain bikes as drum sticks to a drummer (see: Parliament). Okay, maybe not if you live in Florida, but that’s like listening to Bob Dylan. He may not groove, but that doesn’t mean a groove isn’t a wonderful thing.

Consider, if you will, that a mere 1cm drop in a bicycle’s bottom bracket can change the character of how a bike handles. Now, consider that most of the weight of a rider and bike is in the rider, so dropping a rider’s center of gravity by 10cm will do more to affect a bike’s handling than a 1cm drop in the BB. The math on this is pretty compelling, to the point that I don’t really think much about a mountain bike’s BB drop. What’s it matter? Once I get the saddle out of the way, I can do whatever I need.

In 2015 I rode a Specialized Diverge at the Old Caz Grasshopper. On the opening descent, I lowered the saddle a mere 50mm and proceeded to drop veterans of that course. I could hear them get wide in the turns and then the sound of brakes, followed by the telltale click of a clipless pedal releasing. That was my lesson in whether or not a dropper was handy on a gravel bike.

Handiness notwithstanding, finding a dropper that fit a gravel bike was a separate issue. Until now, while KS and a couple of other tiny manufacturers have offered droppers with the 27.2mm diameter common to most gravel bikes (rather than the 30.9 or 31.6mm diameter common to mountain bikes), actually finding said dropper was not easy.

All that has changed. Crank Brothers and Shimano PRO both offer droppers in a 27.2mm diameter. With Crank Brothers all the droppers are internally routed, while Shimano’s PRO line offers both internally and externally routed posts.

Crank Brothers offers their Highline ($249.99) dropper in 60, 80, 100 and 125mm lengths, plus a stubby version of the 60 for smaller frames where the post length is limited by the seat tube or bottle bosses. The Shimano PRO Koryak comes in a single length, 70mm, while the Tharsis comes in a 100mm version; either post goes for $299.99. Both Crank Brothers and Shimano offer great instructions on how to measure the exposed seatpost to calculate which length a rider should purchase. I had enough post exposed to go with the 100mm length. All of the posts feature no offset.

My big criticism with the Specialized dropper was that the release lever mounted to the bar top, not in the drop, which is to say that by the time I was ready to drop the saddle, I was already going downhill and moving my hand away from the brake lever seemed a sensible as huffing cyanide. Both the Crank Brothers and PRO posts feature a release that mounts just below the control lever and can be actuated either with the thumb from the drop or with fingers from the hood.

The lever idea is brilliant, but the execution does have one fault—and this is true for both (I suspect they come from the same factory). The cable housing entry to the lever should be tilted back to the bar about 45 degrees so that there isn’t such a hard bend in the housing as it enters the lever, which creates enough cable friction that releasing the post with my thumb requires a very firm push. It’s possible that I could alleviate this some by moving my levers up higher on the bar, which would allow me to move the release up as well, but that would change my fit and that’s a non-starter.

I mounted the Crank Brothers post in my Allied Allroad, which runs Shimano GRX Di2. Because I could no longer mount the battery in the seatpost, I wrapped it in packing insulation and simply slid it down into the seat tube after running the cable and housing. And let me say that the process of trimming the housing to length is quite the logic problem, way worse than running the cable initially. Double the complexity if your handlebar features internally routed cables. My advice: pay a shop to do this.

The dropper mechanism itself is unremarkable in that it’s the same one found on other Shimano PRO Koryak posts and performs flawlessly each time I press the lever. There’s a reason why most droppers are spring-loaded and cable-actuated.

So who should buy this? Anyone riding gravel bikes down even moderate grades; a descent need not be fall-line steep for a dropper to be useful.

One surprise: I find that after lots of singletrack descending with this thing that my quads are fatigued in a way that does not happen when I’m mountain biking. My working theory is my legs have to support more of my upper body weight when I’m in the drops as opposed to when my hands are on the grips of a mountain bike. Trust me, it’s a happy problem.

Final thought: I’m willing to take my gravel bike on many more trails now.

Join the conversation
  1. jasonbbaker says

    I’m interested to hear more about dropping the Di2 battery in packing material down the seat tube. I know the packing material is to keep it from rattling; is it effective? Will it be easy to fish out the battery when needed? It would seem that if it were “loose” enough to just drop out when the frame is inverted, then it might be prone to rattle?

    I’ve been eyeing PNW’s line of droppers, which has some 27.2 options. Any experience with those?

    1. Padraig says

      Jason: Yes, exactly. The packing material is to keep it from rattling and yes, it’s been enough to keep it silent, and honestly, I was terrified at the work that lay ahead if I *didn’t* manage to silence it on the first effort. And also, yes, it’s still loose enough in there that if I invert the frame I’ll be able to get it out, though with the dropper post housing, I don’t expect it will drop out without a tiny bit of effort.

      I haven’t tried PNW’s droppers, but they are on my radar. Their products tend toward the solid, so I’d bet it’s not a big risk.

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