“Hacking” Thumb Shifters In The Name of Hybrid Road Bikes

from Rookie’s Keyboard 

Hello, friends

Today, I am going to tell you some important technical points regarding thumb shifters and the possibility of integrating them into a road bike/drop bar setup. 

Why would you want to do that? 

Well, the main incentive would be to combine road bars with an MTB mech (derailleurs) and drivetrain. In some cases, road shifters can’t operate with MTB derailleurs. Thus, one of the solutions is to find a way to mount standard MTB shifters on drops.

The Sizing Issue 

And guess what? The only place where you can install those on a set road drops is the flat section a.k.a. the tops. Any other location makes no sense. 

And the diameter of the bars there is thicker at around 23.8mm. The difference isn’t insane in and of itself, but it’s enough to make your life harder. (I’ve seen mechanics try to do this without knowing of the difference in diameter – it doesn’t work well.)

Hacking Them Shifters

One option is to just file the inner side of the trigger shifters’ clamps. You can use a round file for metal. However, it will be quicker to use a rotary tool with a sanding attachment.

A rounded metal file will get the job done

The only downside is that the clamp will get slightly weaker. But to be honest, who cares? It’s not like you need the stronest clamp out there. And during a fall, it can break anyway.

If you don’t feel like hacking your shifters, you can use other methods to acquire a similar setup. 

Shimano A050

There are models with a big enough clamp for drop bars. The cheapest and classic option found on some entry-level road bikes like the Tribans is Shimano A050. 

The model has a large 25.4mm clamp (nice) but is limited to 7-speeds – in other words, it can only operate with 7 cogs at the back. 

Dia-Compe Wing Shifters

Dia-Compe (the brakes on my 1987 road bike are made by the same brand) have a set of hybrid thumb shifters that go behind the hoods. The clamp can work on handlebars ranging between 22.2mm and 24mm. The good news is that the shifters operate with 11-speed cassettes. The bad news is that they aren’t readily available. You will have to order them online.

Paul Thumbies

Paul Thumbies are just clamps that allow you to mount otherwise non-thumb shifters onto any handlebars.

For example, if you have bar-end shifters, you can get a Paul Thumbie clamp and install the shifters on drop bars.

Suntour Command Shifters

Suntour Command Shifters are ultra-old-school-shifters that go behind the brake hoods too. 

They aren’t produced anymore and finding them could be a long and troublesome experience. But if you can get them, they’ll get the job done.

Retro Steel Drop Bars

Currently, the vast majority of drop bars are aluminum or carbon. But back in the day, they were steel. And since steel is denser than aluminum, it can match its strength while being thinner. And guess what? Retro drop bars are indeed thinner and can accept 22.2mm triggers just fine. 

The benefits?

Why do this at all?

The pros of this switch are:

  • You can combine cheaper MTB parts and low-range cassettes with drop bars. This is the main incentive to do this trick.
  • You get to avoid downtube and bar-end shifters common for some retro builds. I have nothing against downtube shifters. They are awesome. But some people don’t like them.

The downsides?

The only downside (besides the need to hack the clamps) is that you can only use the shifters from the tops. In other words, you can’t shift and brake at the same time and there is a delayed gap between the two actions that can hurt your stability. 

So, if you want maximum aggression and drop bars, this isn’t the greatest solution. You will be better off with dedicated brake-shifters.

Ok, brothers. 

It’s time for me to end this post and go out for a ride. 

Until next time,

– Rookie






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