PAP Wonders...Long Cage, B-Screw and Roadlink

Have you ever felt you needed more gears? More lighter, easier gears to climb? Putting a large cassette may be one of the first things that came into your mind (a road triple may offer more range but this is not a possible option because of availability reasons). By large, we mean 32t and bigger. Mountain bike cassettes on road bikes? Why not? It sounds like a good idea. But, can the rear derailleur handle it?

A Road bike rear derailleur. Highlighted is the Cage and the B-Screw.

For this article, we'll explore three ways to mount a large cassette on your road bike. These are a Long Cage rear derailleur, adjusting the B-Screw and adding a Roadlink. Let's start with what sounds most interesting - the Roadlink. This range-increasing revolutionary invention has been around for a few years and chances are, you might have heard about it.


Recently, we were able to get a Roadlink and try it out. What it does is to move the (road) rear derailleur down to accommodate larger cassettes. It can accommodate up to 40t for both 10 speed and 11 speed groupsets in both single and double chainring setups. Here is the compatibility information on the website:

Cassette Sizes.

Is it always needed? No. The purpose or objective is to mount larger cassettes on road bike drivetrains. This oftentimes depends on the rear derailleur. Can it handle the large cassette? Roadlink? Sometimes yes, sometimes no.

Long Cage is type of derailleur with a long arm (the part that connects the two pulleys). Long Cage rear derailleurs can manage large cassettes as well as the large gaps. These are normally designed for Triple setups (3 chainrings). Most mountain bike rear derailleurs (except for those downhill-specific ones) would normally have a long cage rear derailleur because these demand very large cassettes. Also, a Road Triple has a long cage rear derailleur to handle the wide gear range of the three chainrings. On typical road bikes, the rear derailleur is either Short Cage or Mid Cage. These are meant for the smaller cassettes spec'ed on road bikes. (You can also google SRAM's WiFLi system which also allows for large cassettes)

Here is a mountain bike rear derailleur with a long cage. This can handle a large cassette (34t in the picture) as well as a triple crankset.

Here is a Long Cage road rear derailleur. This one is designed specifically for a road triple. Pictured is a 34t cassette. The rear derailleur can easily accommodate up to 36t.

The B-screw is where a little cheating can be done. The B-screw of the rear derailleur (along with the dropout of the frame) can help mount a large cassette without needing the Roadlink. Turning the B-screw clockwise (inwards) pushes the rear derailleur rearward. This moves the rear derailleur out of the cassette's way - allowing for a bigger cassette. With just the B-screw and the "right" dropout ("right" = one that can make the setup work), a large cassette can be fitted.

 Here are two examples of  regular Shimano Sora rear derailleurs that can handle 34t cogs. By turning the B-Screw, the rear derailleur is able to clear the large cogs.

Here is a Shimano 105 (10 speed) rear derailleur with Shimano Deore 11-34t mountain bike cassette. With a B-Screw turned in almost to the max, the rear derailleur cleared the cassette. Note that this model is for a road double setup and not for a triple.

Not a Long Cage? Not enough B-Screw? Then, Roadlink. As we have said earlier, the Roadlink allows for bigger cassettes. I put my Roadlink on a (short cage) SunRace/Driven NRX rear derailleur, which nicely matches my SunRace/Driven NRX shifters.

A close up shot of the Roadlink.

My rear derailleur is originally designed to handle only up to 25t. On this bike, I mounted a 27t and made it work although the top pulley of derailleur is almost touching the cogs. The Roadlink put a fair amount of space.

Next, I mounted a Shimano Tiagra 12-30t cassette. The rear derailleur still clears the cassette. This is an impressive improvement for me from the recommended 25t to 27t to 30t - for a short cage rear derailleur.

For science, I tried to go BIG. I maxed the B-screw and put the largest cassette I can find. It is a 11-34t Shimano Deore cassette. It still clears! Now I can prepare for any climb.

Are there any downsides? The biggest downside is when you have a short cage rear derailleur. It may be able to clear the cassette but maybe it cannot handle the large range. By cannot handle the large range, I mean that at an "inappropriate" combination (big chainring and big cogs), there is too much chain tension. I know I shouldn't be there, but it's very difficult to always keep track of which cog you are in - at all times. This big-big problem can be remedied by putting a longer chain. Just avoid using the little chainring-and-smaller-cogs combination (another "inappropriate" one) because here there is too little chain tension and the chain slacks. Well, these are not really deal-breakers for me, so I'll just keep this in mind.

Bottomline: mount a bigger cassette. Why? To climb [anything].

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