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Adding a downtube shifter(12 posts)

Adding a downtube shifterFSRslug
Dec 9, 2001 10:30 PM
I would like to add a downtube shifter to my mountain bike that is being converted into a road/cross bike and would like to know if it is possible to drill and tap a hole to accept the shifters or what my options are. I dont want to spend much money, I have access to tools. Any suggestions?

Here's what to do:Rusty McNasty
Dec 10, 2001 4:13 AM
Take a large (maybe 3/8") drill bit, and drill straight through your downtube, from one side to the other. If you wish to lighten the frame, drill a few more holes while you are there, too! Then, taking a carriage bolt of about 3" length, stick it through, and torque it down until the tube starts to bend. Then, add some old simplex levers to the bolt. Go ride your bike. Take a few jumps.
Any questions??
did the kids at school take your lunch money again Rusty?RaiderMike
Dec 10, 2001 3:27 PM
So you have to come here and lash out to some dude who is just needing a little info? All done in the safety of cyberspace of course. If you cant say something that will help the guy, keep your wiseass opinions to yourself.
re: Adding a downtube shifterscottfree
Dec 10, 2001 6:27 AM
Hmmmm, what are you trying to accomplish? A bar end shifter might be more easily do-able.
What i'm trying to accomplish....FSRslug
Dec 10, 2001 8:02 AM
I am in college and can't afford a road bike right now. I have a few mountain bikes though, one of them I dont ride anymore. I want to turn it into a road/cross type bike. I have lots of parts, both moutain and road. What I dont have that I want is a pair of STI/Ergo shifters. I do have a few sets of downtube shifter, none are clamp-on, and just want them on there.
No such luck...TJeanloz
Dec 10, 2001 8:21 AM
If the frame is steel or ti, you can have a downtube boss brazed on. But that won't be a cheap option. Old style clamp-on mounts don't work satisfactorily with index shifting- and that would be a major compromise.
Dec 11, 2001 8:15 AM
But they'll work fine with friction, right? I'm trying to parse out this sentence. Are you saying that not having indexed shifting is a major compromise? Interested to know why you would say so.
Dec 11, 2001 8:34 AM
Yes, they will work fine in friction mode. But frictioning an 8 or 9 speed system isn't the easiest thing in the world. If you're used to friction shifting, go for it, to most, that's a lost art.
Something I didbrider
Dec 10, 2001 2:38 PM
I just used a set of MTB shifters mounted on the bar tops fairly close to the stem. Helps if you can cross the cables under the down tube.
Depending on your frameKerry Irons
Dec 10, 2001 6:02 PM
The tube walls are way to thin for drilling/tapping on any frame. A "thick" steel tube is 0.6 mm - how many threads do you think you could get in that? "Thick" aluminum might be 1.5 mm. In any case, you would need to add a boss of some sort - like the bottle cage bosses seen on many Al and Ti frames. Then you need the mount for the shift lever - look at a bike with DT shifter bosses and you'll see what is needed. Can you say "thumb shifter"? 'cause your current proposal is a non-starter.
No big deal, apparentlyTrent in WA
Dec 10, 2001 9:07 PM
Assuming that you're already planning to put drop bars and road-bike brake levers on the bike, and that you have some downtube shifters already, just get a set of bar-end shifter mounts (available from Rivendell, among others: and mount your shifters there. If you join Riv, it'll cost you $27 + s/h and you'll be subscribed to their quarterly magazine, which is well worth reading. Cheap 'n' easy solution.

Even cheaper, also at Rivscottfree
Dec 11, 2001 5:08 AM
Check this link instead, scroll all the way down:

Top-mount thumbshifters, 12 bucks. Elegant solution.