ghostm42

Will thumb shifters fit on bullhorns or road drops?

I purchased my bike from an abandoned bike auction a few months ago. The original STI levers were missing. I can't afford STI or barend 9-speed shifters... or even barend friction shifters. It has no braze-ons for DT shifters and threadless stem (so no way to mount stem shifters). My only option seems to be thumb friction shifters. The thumb shifters are usually for mountain bikes, so I don't know if it'll fit bullhorns or drop bars (I know the bar diameters between mtn and road is just slightly off).

I was considering these:

https://www.niagaracycle.com/product_...ucts_id=418214
https://www.niagaracycle.com/product_...ducts_id=11971

or

Shimano Tourney thumb shifters, but I don't know if the indexing can be switched to friction to support 9-speeds.
https://www.niagaracycle.com/product_...ducts_id=15889

dddd

The Tourney levers are mechanized and don't support friction.

Any clamp made from sheet steel can be adapted to the 23.8mm road bar diameter. But the center sleeve is another 2mm bigger so where do you plan to mount them?
A longer bolt works up to a point, then must be curved and so secured with a nut (since you can't turn a bent bolt).

I've always managed to mount the suckers somehow, from the above choices. I usually run them with one cable above the other so as to get them closer to the bar's center. Looks asymmetric but functions fine.
Note that 9-speed bar end shifters turn up used, usually for about $40. Nine-speeders seem to be a bit cheaper than others.

Lastly, I've also used chromed-steel road bars from cheap ten-speeds like Varsities and such. The clamp diameter will be 25.4mm but there's usually no sleeve and the bar's diameter is only 22mm (same as mtb bars).
This opens up the options to include cast-aluminum, higher-quality XT thumbies.
It also allows Grip shifters to slide on, once modified as follows: The inner and outer sleeves of the GripShifter must be slotted along most of their length, two slots 180-degrees apart. The end of each slot should be terminated with a drilled hole to prevent cracking and the hole must be drilled first, then the slots are sawed to meet the holes. The shifter is slid onto the bar one sleeve at a time, then assembled on the upper flat portion adjacent to the stem clamp.
I've even similarly modified Suntour twist shifters that have a somewhat different design, that was tougher in terms of time spent.

Jeff Wills

Either of those will work, sort of. Road bike bars are 1.6mm larger in diameter than mountain bike bars, so you'll have to mangle the clamp and use a longer bolt. As DD says, it's been done but it won't be pretty.

Have you tried hunting down used friction bar-end shifters? They're darn near indestructible and usually fairly cheap. I've seen some at the local used-bike-parts emporiums for $25.

ghostm42

Nice advice. I'm trying to mount them on the flats of the bar (or really, anywhere else), not the wider center sleeve.

I've tried to look for barend shifters for a while now, but couldn't find anything local and affordable. They tend to go for $50 for friction ones.
I didn't realize old road bars had a smaller diameter. This could be an option, but I'll need new drops. I'll keep this one in mind.
I think friction thumb shifters may still be my best bet, given that they are very cheap. It'll just be a tight squeeze. And if I can't manage, they should still work on the old road drops.

BCRider

It's not so much a case of old road bars as CHEAP road bars from the old chromed steel used for everything 10 speed era.

If you're patient with a Dremel or a small half round coarse file you can hog out the alloy clamp areas of mountain bike trigger shifters to fit. Once you get them to where they are a finger push on over the end of the bar you can wedge the clamp open a little more to allow them to go around the bends and into the area near the center. I did that on my old commuter/touring bike many years ago when road bike brifters seemed to be priced like gold. It makes things around the center a bit busy looking but it worked well for years.

surfrider

As mentioned above, the older road bars will work, as will using a Dremel tool or file to enlarge the hole in the shifter levers. Another problem with newer road bars is the under-bartape cable groove(s) formed into the metal seem to make the handlebars slightly oval in shape; once you get the shifters ground out to fit over the end of the bar, they may need a little extra file work to get them all the way up top where you'd want them.