rccardr 

I just hate STI brifters. Only have one bike with them (it's my only non-Cannondale), but just...hate 'em.

Am looking at the available new DA 10 speed DT shifters but as far as I can tell (and according to sellers) they don't come with a clamp. My bike doesn't have braze-ons for DT's, and since it's aluminum I can't have them brazed on (well, I suppose I could have them TIG welded on, but that would mess up the paint). The current cable stoppers are welded on, so no luck there, either (although they are high enough on the downtube that they will be out if the way of the shifters should I find some way to clamp 'em on).

Has anyone else done this already? Am I missing something here- like maybe there are clamps available separately in different sizes that I've blindly bypassed? A little help for an elegant soultion would be appreciated!

Thanks
Doc

norwood

There's this: https://www.cycle-frames.com/bicycle-...-AL-FRAME.html

But I'd be more than a little hesitant, drilling a hole through your alum. frame tube

I'd recommend bar-end shifters.
Clamps just don't seem to exist for larger alum. tubing sizes.

canopus 

I have two older cannondales, the SR300 has a setup very similar to the kit described above. You had to be careful when screwing them together though as you could conceivably crush the tube. and you do have to use some type of epoxy or lock-tite because if you don't get the post tight enough when you shift one side it could move and the other will do an autoshift. My SR300 does this if I have the front derailler post to tight.

My ST400 on the other hand is much nicer, it is a one piece DT post typical of a brazeon but on each there are two holes drilled and these have rivets that hold them to the downtube. A much better mounting than the SR frame.

I wouldn't worry about drilling the aluminum tube, just use a new/good titanium bit. Maybe you can call Cannondale to see it they have any old rivet posts one lying around...

operator

Lol

HillRider

Some of the Klein Aluminum frames had their OEM downtube bosses fitted using a threaded rod run through opposing holes in the downtube with the shifter bosses screwed onto it so drilling small holes in the downtube doesn't seem to pose a problem. AFAIK, no one makes adapter clamps for current large diameter tubing.

However, I second operator's "comment". I've ridden extensively with dt shifters and STI/Ergo brifters and I FAR prefer the brifters.

operator

I'd like to know how the OP plans on drilling said hole (let's pretend this is a smart idea on a cannondale, AL tubed bike) perfectly perpendicular to the actual downtube. If it's off you will create stress risers when those puppies are clamped down which will lead to tube failure.

We have seen this before, even on a steel bike that had properly brazed mounts just from overtightening AL dt shifter mounts.

canopus 

It is real easy with a wooden v-block, Drill Press and center punch...

canopus 

another question I have is to the OP. Have you pulled off your cables stops on the C-dale? Could they possibly be DT bosses already?

HillRider

Apparently this is a newer Cannondale and the cable stops are welded very high on the downtube or on the headtube and are non-removable. Many frames now come with dedicated and fixed cable stops as they are expected to be used strictly with brifters or barends.

canopus 

Once again limiting choices...

HillRider

Sure, they make what sells. How many Chevy sedans can you buy with a manual transmission these days?

Booger1

If holes in tubes cause stress risers,we're all in big trouble.Tubes have holes at each end.

In my line of work,we drill holes to eliminate stress risers,imagine that!

rccardr 

Thanks for all of the replies, folks. As mentioned in the original post, this isn't a Cannondale frame but it is aluminum. Having stripped a couple of those guys down for powder coating I'm very familiar with Cannondale's method of mounting the DT shifter bosses, although I wasn't aware that anyone was selling a similar aftermarket setup (thanks, Norwood!). And Cannondale is definitely very short on parts for the older bikes. Still, I was hoping to avoid drilling the frame in case a future owner actually enjoyed the brifter thing. All a matter of taste, I suppose.

Canopus, the cable stops are dedicated and welded to the frame. Sadly, they hide no opportunity for modification...

Anybody know a good machinist who might be interested in doing a clamp for a larger downtube that would accept shifter bosses? Bet it wouldn't be too hard for the right guy...and who knows, there might actually be a broader market for it!

HillRider

Well, it wouldn't be pretty but could you drill out a stainless steel radiator clamp and use it to hold downtube bosses in place?

rccardr 

Ta-Da!!!

https://www.niagaracycle.com/product_...ucts_id=401492

If the threads on this clamp are the proper size (or can be made the proper size) all I need is the right size clamp for the downtube (or one close/large enough that I can ream it out to fit). Thoughts?

HillRider

The threads on that clamp are most likely M5x.8, the same as most dropout eyelets and water bottle bosses AND downtube shifter bosses. Maybe it will work if it fits your downtube.

operator

Learn comprehension and reading skills please

zzyzx_xyzzy

That clamp won't stretch open for you to be able to get it around your downtube.

Maybe start with a two piece clamp like this https://www.mcmaster.com/#9638t14/=4247vx and drill/tap a screwhole into it to attach the Nova shifter boss.

roadfix

How about going with bar-end shifters? Route the cables ergo style and you've got yourself a nice, clean, uncluttered look...
Don't mess with your beer canned down tube.

rccardr 

OY! Even better, zzyzx_xyzzy!

All I need to do is get the right bore size, then presto!

Chris_W

I'm also frustated by the fact that modern frames don't come with down-tube shifter bosses. Unfortunately, I haven't found a good solution yet, so I'll be interested to hear all suggestions that people have. Personally, I like to run a brifter on the right side to control the RD, and a down-tube shifter on the left for continuous control of the FD.

One bar end shifter on the left is another possibility, but I don't like it when I hit my knee on it when standing up to climb. The bar end shifter also necessitates extra cable housing, and clutter that isn't needed. A DT shifter is perfectly sufficient for the FD, and works better than a brifter in some respects.

joejack951

Look harder for a frame. My 2004 Look CF frame has downtube shifter bosses and so does my 2008 Gunnar frame. I'm sure there are plenty of others. There's also always the custom route where I'm sure there'd be no problem having DT shifter bosses added.

Chris_W

I agree that it is still possible to find such a frame, but it is becoming more and more difficult. I recently bought a new bike that was ideal in almost every way except for not having DT shifter bosses. I wasn't going to not get the bike just because of this shortcoming, but now it is bugging me.

I found one more item that could be of use on frames with a down-tube of up to 34.9mm diameter. It's designed for mounting an MTB chain guide, or for a pulley to reverse the cable pull direction for a FD. Maybe it could be adapted to be used as a shifter boss?



EDIT: One more thought, maybe you could put the 28.6mm version of this in place of a headset spacer and mount a DT shifter on the steering column, just like the old-school stem-mounted shifters. It's not ideal, but I think I prefer it to the other options (STI, drilling through my frame, bar-end, or Paul Thumbies). However, I may still hit my knees on it when I stand up, so maybe it's not such a great idea.

vredstein

Elegant might not be the word, but I've been running this setup for four years. Once you get used to it, you can shift from the drops, tops, and hoods.
https://www.kellybike.com/2nd_xtra_takeoff.html

operator

Yup.

Plenty of production bikes still come with DT shifter bosses. Marinoni still makes bikes with them, Surly. You're obviously not going to find race bike lineups like cervelos/pinarellos/colnagos with dt shifter bosses.

The amount of people walking in and asking for bikes with downtube shifters is about zero or close to it. There's no point. You're not going to find widespread availability of modern bikes with downtube shifter bosses, just not going to happen. What next, threaded headsets? Cottered cranks? Steel rims?