A Switch From Downtube Shifters To STI Is Possible But Pricey and Potentially Illogical

It’s possible to convert a bike with downtube shifters to STI brake-shifters, but the needed parts could make the conversion too expensive.

The Components Needed For The Conversion

A conversion from downtube shifters to brake-shifters will require the following components:

1. STI Shifters or Other Brake-shifters

Shimano Tourney STI Shifters

The new brake-shifters a.k.a. brifters will more than likely be the most expensive purchase on the list. The cheapest STI shifters that I could discover were Shimano Tourney 2/3×7.

Most places have them around USD 80-120 (depending on whether they’re on clearance). Unfortunately, however, they seem hard to find.

If you want more speeds (e.g., 8, 9,10), the price of STI shifters goes up a decent amount.

If the bicycle isn’t particularly expensive, the brake-shifters could end up costing more than the bike’s value on the second-hand market.

FAQ: Why are brake-shifters so expensive?

Brake-shifters are expensive because they’re considered a premium product and include a multitude of small parts that have to operate under great stress.

The internals of a brake-shifter are among the most technical parts of a road bike and are difficult to assemble.

FAQ: How many speeds should I go for?

7 speeds are the minimum as there are no STI shifters for fewer speeds. That said, you can go for 8, 9, or even a 10-speed cassette as long as the rear hub can accommodate it.

Unless you want a 1x drivetrain, you will need a shifter for the front derailleur too.

If you run a double crankset, you can use either a 2x or 3x shifter.

If you have a 3x shifter and a double crankset, you will have to heavily limit the travel of the front derailleur via the limit screws.

2. New cassette

Unless you’re already using a modern cassette, you will need a new one with up-to-date spacing between the cogs.

This is necessary because brake-shifters use index shifting and therefore pull the cable a pre-determined amount with each click.

If the cassette has a different cog pitch (the center-to-center distance between two adjacent cogs) than the current models, the shifting won’t be as good.

3. New Rear Wheel

The conversion may require a replacement of the rear wheel too.

This procedure will be necessary in the following scenarios:

a. Old 6-speed System

If the bicycle uses an old 6-speed system, a new rear wheel with a modern hub will be needed.

b. 7-speed Specific Hub

If the bike has a hub designed for 7-speeds, and you want to run a cassette with more speeds on it, you may need a new rear wheel.

Having said that, this isn’t always the case. Some 7-speed hubs can actually accommodate 8, 9, or 10-speed cassettes.

If the 7-speed cassette is installed with a spacer at the back, then the hub is wide enough to work with more gears.

If there’s no spacer, and the 7-speed cassette covers the entire hub, a new wheel will be necessary.

The Frame May Be Too Narrow For a New Wheel

One of the problems that you may run into when installing a new rear wheel is the lack of frame clearance.

Some 7-speed hubs have an O.L.D. of 126mm. The term O.L.D. refers to the usable part of the rear hub and is essentially the distance between the outer sides of the hub’s locknuts. 

The O.L.D. of modern road wheels is 130mm when using caliper brakes and 135mm when relying on disc brakes.

Therefore, a retro frame designed for 126mm O.L.D. hubs won’t be able to accommodate a new wheel.

If the frame is made of steel, it could be “cold set” to accept a wider wheel, though. However, this adds another step to the process and complicates it even further.

4. New Rear Derailleur

If the rear shift ratio of the current rear derailleur does not match that of up-to-date models, the rear mech will also have to be replaced.

The rear shift ratio is expressed with a single number which signifies how much the rear derailleur moves for every millimeter of cable pulled or released by the shifter.

For example, the rear shift ratio of Shimano 9-speed road derailleurs is 1.7.

This means that for every millimeter of cable movement initiated by the shifter, the derailleur moves 1.7mm.

If the rear shift ratio of the derailleur is 1.4 for example, then the shifter will fail to control the derailleur as expected.

Consequently, the shifting experience will be poor because the derailleur will keep moving the chain to the wrong places. To prevent this, one will have to purchase a derailleur compatible with the brake-shifters in question.

Note: Suntour’s Accushift rear derailleurs are known to be incompatible with Shimano’s index shifters due to the different rear shift ratio and cassette spacing.

However, if the derailleur is Suntour and made before the Accushift area, there’s a great chance that it will work to a satisfactory level with an indexed Shimano system.

5. New Front Derailleur

The front derailleur may have to be updated too as it may index poorly with the new shifters.

Luckily, the front derailleur is among the cheaper parts, especially if you find a good second-hand offer.

6. New Chain + Chainrings

If the chain is worn or you want to move up to 10 speeds, you will need a narrower model.

If the current chainrings are too thick to operate with it, new, thinner ones will have to be provided.

7. Downtube Cable Stoppers

The downtube shifters have to be replaced with downtube cable stoppers which will also play the role of barrel adjusters tunning the gear settings.

Shimano Downtube Cable Stoppers

Most types mount to the downtube shifters bosses via an M5 bolt – the same size used for the bottle cages.

8. New Cables + Housing

The brake-shifters necessitate new cables (shifters + brakes) as well as housing.

While it’s possible to use some of the old stuff, it’s always best to install a set of new cables and housing when changing shifters in order to monitor the performance of the new system with greater accuracy.

If you couple the new shifters with the previous cables and housing, the performance may be less than optimal due to the older gear rather than structural inferiority.

Besides, you’re probably doing this conversion to experience faster and smoother shifting. New cables and housing support that goal tremendously.

10. New Bar Tape

There’s a very high chance that you will need new bar tape due to the different cable routing. Also, if the bicycle is old, chances are that the bar tape is worn out anyway.

11. New Bottom Bracket (Possibly)

If the bottom bracket is positioning the chainrings too far away for the new front derailleur to reach them, you will have to replace the spindle with a shorter one (if possible) or the entire bottom bracket.

12. Tools + Utilities

If you intend to do the conversion yourself, you will need the following set of tools to get the job done:

  • Cable + housing cutters
  • Cassette removal and installation tool
  • Chain whip
  • Chain Breaker
  • A set of Allen keys
  • Philips screwdriver
  • Crank Removal Tool (if you’re going to replace the bottom bracket)
  • Bottom bracket tool(s)
  • Wrenches
  • Pliers
  • Insulation tape (to install the new tape)

If you don’t intend to do the conversion yourself, the price will go up as bike shops charge a lot for their services. At least, that’s my experience where I live.

If you count on the bike shop to source the components, you will pay even more because they’ll charge you a retail fee without looking for special discounts online.

Calculating The Cost of The Conversion

The table below contains the required parts and their estimated price in a situation when you have to replace the greatest number of components.

The actual price tag will depend on the shop from which you’re buying, but in most cases, it will be close to the values below:

Shimano Sora Di2 STI ST-R3000USD 155
Shimano CS-HG400-9 CassetteUSD 20
Shimano WH-R501 28″ Rear WheelUSD 85
Shimano Sora RD-R3000 9-speed Rear DerailleurUSD 26
Shimano Sora FD-R3000 Front DerailleurUSD 25
Shimano Sora FC-R3000 2×9-speed cranksUSD 77
Downtube cable stoppersUSD 15
9-speed chainUSD 15
Bar tapeUSD 8
Cables + housingUSD 15
Total: USD 441

As you can see, this conversion could end up costing you a ridiculous amount of money.

Making The Conversion Cheaper

Below are a few options that may help you save money:

1. Buy second-hand parts and do the work yourself

You may find some good offers on Facebook’s market place or sites for used items. If you’re unsure about an offer, ask for advice online.

2. Stick to 7-speeds

7-speed brake-shifters tend to be the cheapest. Unfortunately, however, they’re getting hard to find.

3. Switch to a 1x Drivetrain

If you switch to a 1x drivetrain, you won’t need a second brake-shifter and a front derailleur. The downside is that your gear range will be highly limited.

4. Keep One of the Downtube Shifters

Using a downtube shifter for the front and a brake-shifter for the back is a neat way to save money, combine the best of both worlds (index+friction shifting) all while preserving the gear range.

This set-up eliminates the need for a front brake-shifter and reduces the bike’s weight too.

Many people love front friction shifting because you can easily “trim” the derailleur and prevent “chain rub” against the cage.

Lance Armstrong used a similar set-up (downtube shifter front + STI back) for some races. The goal was to save weight (about 100 grams), avoid chain rubbing, and reduce the chances of dropping the chain.

The Length of the Process

The duration of the process depends on how many parts you have to replace.

Scenario 1: 7 Speeds

If you want to preserve a 7-speed system, the steps will be as follows:

1. Remove the old bar tape, detach the brakes, and take down the old shifters.

2. Replace the cassette with a 7-speed one spaced properly for modern index shifters.

If the current hub cannot accept a modern 7-speed cassette, it will have to go too. The cheapest way is to simply buy a new wheel.

3. Put on the new shifters

4. Replace the rear derailleur

5. Reattach the brakes

6. Install the shifting cables

7. Install a new chain and test set-up.

8. Adjust the limiting screws on both derailleurs.

Scenario 2: 7+ Speeds

If the frame can accept a modern 130mm hub, the process of upgrading to more speeds will be similar.

The only difference is that you will need brake-shifters and a cassette designed for more gears.

If the frame is too narrow, you will have to cold set it to 130mm or live with a 7-speed system.

Note: Cold setting can be done only if the frame is made of steel. Other materials do not tolerate it.

Every Case Is Different

Due to the high variety of retro bicycles, it’s difficult to predict every problem that you could run into. It will be helpful if you prepare yourself mentally for surprises. You can’t know what you will run into until you actually begin the conversion.

It May Be Cheaper to Buy a New Bike

Given the investment, it may be wiser to buy a new or second-hand bike that already has STI shifters.

One of the reasons why the conversion is so pricy is that components are always more expensive when bought separately.

Frequently Asked Questions

What Are The Benefits Of Converting To STI Shifters?

STI shifters and other brake-shifters offer the following benefits:

Comfort. Shifting is more comfortable because you can do it from the hoods.

Speed. Downtube and bar-end shifters cannot match the efficiency of STI shifters and will always be slower because they require the hands to move over a greater distance.

Also, STI shifters are indexed. All you have to do is click one time to change gears. Meanwhile, the older shifting models are working in friction mode and force you to search for the gears yourself.

Friction shifting has many benefits for touring cycling, but when it comes to speed, index shifters are simply better technology.

Safety. Unlike downtube shifters, brake-shifters do not require you to move your hands away from the handlebars. This characteristic makes them safer because your balance isn’t disturbed every time you have to shift.

What Are The Downsides of Brake-Shifters?

The main downsides of brake-shifters are their price tags and the lack of spare parts for repairs. Once the shifter breaks, it’s very difficult to get it working.

The good news is that brake-shifters produced by reputable companies are plenty strong and can last a really long time.

Another characteristic of brake-shifters which could be a weakness in some situations is that they’re indexed and therefore compatible with fewer components.

Meanwhile, friction shifters allow you to mix MTB and road parts because you are not tied to a specific shift ratio. Hence why many touring cyclists keep relying on bar-end shifters that have a back-up friction mode.

What Are The Advantages of Downtube Shifters?

The main benefits of downtube shifters are:

Simplicity. Downtube shifters are quite simplistic in comparison to brake-shifters.

Independence. Downtube shifters are independent of the brake levers. Therefore, if something goes wrong with the brake levers, you will still have the ability to shift.

Durability. The basic engineering of downtube shifters allows them to last a long time.

Friction shifting. As already mentioned, friction shifting is beneficial for those who want simplicity combined with the ability to mix MTB and road components.

What Are The Disadvantages of Downtube Shifters?

The disadvantages of downtube shifters are:

Inefficiency. Even if you have a lot of experience with downtube shifters, you still won’t be able to match the speed of brake-shifters.

Instability. You can lose balance while shifting.

Infrequent shifts. Downtube and bar-end shifters encourage you to shift less frequently because it’s more difficult to do so.

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