DropGrip: Gripshift mod for dropbar road bikes

IT IS A WORK IN PROGRESS! It is though, actually built now, at least on a test bar set. I am waiting on some white hoses (to match my main bike's gear hoses) and it will be installed and extensively thrashed. It may still not be an ideal rig, your mileage may vary.

Stardate 07042020 Amended:
OK, so I have vastly improved the design, inspired by finding an affordable hydraulic disk brakeset. I've also worked out instructions for making this and will be making it soon.

My $60 "hydro" brakeset arrived. I’m really quite happy with it. It’s a knockoff of a Zoom commuter brakeset, one needs a bit of a bleed but that’s not a problem because I need to use the back hose for the front brake and trim it and I had to order a whole new hose for the rear because my tourer is so long! It doesn’t feel long⁉️ The bars are dual dual brake rig I want to put on the fat bike, but they’re a useful test platform for proving the concept. There’s actually no 3D printing required for this, but you do need a drill press and a stepped cone bit to make the spar bars. Or you can use the cut off mountain bike bar-ends method in the old notes below.

Parts list is...
A drop bar of your choice, grip shifter set to suit your gears (if your rear mech is 10 speed or higher, there is only SRAM, but 9 speed or below, you have microShift and Shimano), a hydraulic flatbar road or mountain brakeset (or cablepull if you have oldschool brakes), an old donor handlebar for cutting the spar bars (the barends were just 7mm too short) a pair of M5 by 90mm bolts, a pair of aheadset steerer caps and a pair of donor road bike brakes for the ring clamps.

Method...
Using a drill press, because this needs all the accuracy you can get, drill a 4mm pilot hole in the donor handlebar at 98mm from each end.

Replace the 4mm drill bit with a step cone bit that has at least a 22mm step. Drill out the pilot holes to 24mm (but 22 will do with a lot of filing) to almost half way through the bar. Turn it over and drill out the other side to 24mm.

Clean up the outside of the pieces just cut by drilling them with a flat file and the inside of the curved cut with a round file. Discard the bar centre.

From the donor old school road bike brake levers, salvage the the ring clamps that hold them on a drop bar. Also grab your steerer caps and the M5x90 bolts. These will hold your spar bars on your drops.

Fit the grip shifter and hydro brake to each spar bar so they stay in place but can be turned with light to medium hand pressure.

Thread the M5 bolts through the steerer caps and through the flat ends of the spar bars. Fit the ring clamps at the ends with the concave cuts. Then slip each assembly over the dropbars so that the spars point slightly upwards.

Adjust the positions of the brake levers and shifters. Fit brakes, trim and fit hoses, fill with appropriate bicycle brake fluid and bleed the system.

Test ride without bar tape, make any postional trims for comfort and reach, then tighten everything off and tape the bars.

Et voila! Integrated road bike shifters with hydro braking!

The whole system, if all parts are bought new will cost you less than just a hydraulic road bike lever set with integrated gear change. Way less! Mine will have cost me less than AU$135 dollars by the time I roll on the bar tapes!

Enjoy!

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OLD NOTES FOR REFERENCE:
Current photos show a prototype built with junkbox bits. The final assembly will be using parts which have cable paths better suited to offroad use. The gripshift is an 8 speed, I need to get a 9 speed for my rig, which may also get a major modification to have the cable turn back towards inside the handlebar. Literally a cut off, turn around, reinforce and glue back on.

I've been mulling this for months and have decided to modify some bog standard, 22.5mm mountain bike bar ends to work as the spare for this project. The mod involves "trimming" off the flatbar mounts and using a couple of road bar lever clamp rings, along with a 3D printed inner/extended. I've uploaded some photos showing the first prototype. I'm a ways off adding this system to my tourer/commuter yet, but this is probably the closest the idea has come to being practical.

The first attempt at a prototype is actually astoundingly sturdy! However, see my warning above. Mileages always vary.

Also, as my touring bike is a 1x9 (11 to 42), The left side will either be an unmodified brake hood, or I'll make a dummy GripShift. I'll probably also make some flares to transition the gripshift twister to the drop bars more smoothly and give a more ergo shape after taping up.

So, why so much effort when I could just go out and buy road bike shifters? Well, my roady has cable pulled hydro disks (See my Dryline project: https://www.thingiverse.com/thing:3373400 ), and I'd really like to have full hydro and something like an integrated shift. This project is an attempt to realise this. I love bike hacking, almost as much as I like riding and, if I can get this system working well, ergonomically and reliably, it's here for any crazy weirdo who prefers drop bars for ergo, but mountain style group for robustness. Remember, I'm a sometimes cycle tourist, I load my bike up with too much camping gear and hit the road. The MicroShift R9s are good road levers, they're problematic and need regular tweaking when used with mountain gear like an 11 to 42 cassette with a long cage derailleur on a roadlink.

PARTS
Straight mountain bike barends 22.4mm OD, 19 or 20mm ID. (Cut off the bunding end, leaving about 1/4 to 1/3 of the wrap around.)

Road bike lever ring clamps. You will probably find it cheaper to buy the cheapest road bike levers you can and "borrow" the ring clamps from those. They're pretty damned expensive as spare parts. I scrounged mine from a discarded zimmer frame I found on kerbside collection.

M5x80mm bolt. Goes down the inside of the barend, into the ring clamp, replacing the short screw that is used on a normal brake lever.

Gripshifts appropriate to your gearing. I'm running a 1x9, I'm also a big fan of 3x7 single overlap and 3x10 single overlap, although 10 speed limits you to SRAM parts and the price of this rig goes up quickly.

Barend track/tt bike brake levers, the type which wrap around the bar, rather than insert. Diacomp make a good set which can be had for as little as $20 on eBay or from Ali. Nameless brands start at AU$8/pair, AU$ for inline auxiliary levers.

Either 3D print the the barend insert, dropbar-integrated-gripshift.scad or dropbar-integrated-gripshift.stl, You may need to tweak the measurements, hence I've included the parametric (SCAD) file. You could also turn up the end insert with a lathe or possibly machine it with a CNC. I only 3D printed it because that's what I have.

METHOD
First, cut down the mountain bike bar ends at the handlebar end. They need to be 22.4mm to be compatible with the various brands of gripshift and they need to be at least 80mm long. Don't cut too much off the wrap around, but don't cut too little, as the road bike ring clamp pretty much takes all your weight. I think some "dremelling" tp clear a chanel for the ring clamp might be in order, to get more weight on the actual aluminium tube of the barend. They'll definitely need some filing or dremelling to remove burrs and sharp edges.

By now you will have measured your gripshift, brake handle and long M5 screw and made your appropriate barend insert, either by 3D printing from the thing files, or by turning down a threadless hedstem cap to 22mm.

Slip the gripshift onto the barend, put the insert inside the barend, thread the long bolt through the assembly and loosely screw it into the ring clamp. Slip the ring clamp onto the drop and slide it roughly into position and tighten the long bolt so that you can just still move the barend on the curve of the drop until you get a good ergo position. Tighten the long screw until the barend no longer moves, even with force.

Slip your brake lever over the remaining protrusion beyond the gripshift and tighten. Run your cables.

Optionally (and I plan to do this) you can put drop adapters on your flatbar and use inline levers for a flatbar breaking position. This is a cheaper option than some of the adventure drops available (in my day, we called them randonnee bars ;-) ) and more flexible, as you can have your "mountai" brakes inboard or your drops inboard, depending on whether you prefer drops onroad only or switch between drops and flats frequently as the terrain changes.