Solutions For Adding Gearing to Your Road Bike

By Coach Rick Schultz

I was recently in search of more gearing for the Giant TCR Advanced disc brake bike I bought, which I wanted to turn into my “climbing bike.”

Over the past two years, I’ve been doing a lot of spinning drills, working on more efficient pedaling. Now, during any given ride, my average cadence is 102-105. Couple this with finding harder hills (15%+ grade) for doing intervals, and I was looking for more than the 11-28 that came with this bike. I kept the 172.5mm Ultegra 6800 crankset, but changed out the 50/34 for ROTOR’s 52/34 elliptical Q-Rings. Note: the 52 elliptical is a “virtual” 55 round chainring.

So, downloading several Shimano technical documents, summarized in table below, I realized that with the stock Ultegra RD-6800-SS short cage rear derailleur, I was limited to an 11-28T cassette. Further research showed that if I swapped out the RD-6800-SS for a RD-6800-GS (long-cage derailleur), its longer cage could support an 11-32T.

But what if I wanted to go larger than a 32T? The next step up would be a 34T. For this, I would need a more expensive RD-8000 ($54 vs $95) rear derailleur, plus a more expensive Shimano CS-HG8000-11 cassette, which gives me 11-34T.

And what if I want to go even larger than that? Both the SRAM PG-1170 and the PG-1130 cassettes are offered in an 11-36T. Looks like the best option, but there is a problem with the RD-6800-GS supporting this.

 

If want to go even larger, you need to go down one of 2 paths; 1x (single chainring no front derailleur) or 2x (standard road setup with 2 chainrings and a front derailleur). When larger than 11-36T cassette, you are now looking for mountain bike parts; rear derailleurs, large cassettes (40T to 42T) and possibly needing to swap out the front chainrings from 50/34T to 46/36T. The rear derailleur of choice is Shimano’s XT-M8000-GS which can handle up to an 11-42T cassette. Speaking of large cassettes, the SRAM XG-1180, XG-1150 and PG-1130 are offered in 10-42T or 11-42T. Shimano’s mountain bike CS-M8000 is offered in 11-40T and 11-42T.

This, along with what I accomplished is uncharted territory for a road bike, especially running elliptical chainrings.

 

In this table, each column shows arear derailleur along with its supported cassette capacities.

HOW DO YOU MEASURE GEARING?

The industry standard is called gear inches (GI). Basically, it is how many inches the bicycle rolls forward with one revolution of the pedals. Mathematically, it is (FS * WD) / RS, where FS=Front Sprocket, WD=Wheel Diameter and RS=Rear Sprocket. I am using a 700C wheel whose diameter is defined as 26”.

Example, in the table below, (52 x 26)/11 equals a GI of 122.91

In the table below, the columns in blue represent what can be done with off-the-shelf Shimano components. Although, if you want to go with an 11-34, you will need the latest RD-8000-GS. The table in green is what I ultimately configured.

 

Back to my decision. I wanted to go with an 11-36 cassette with 52/34 Rotor elliptical Q-rings. I already had a RD-6800-GS and I purchased the SRAM PG-1170 cassette in 11-36T. After swapping out the rear derailleur and cassette, two problems arose …

• chain rub at the rear of the front derailleur cage, and
• tuning the rear derailleur.

The chain rub was easy to fix, but the rear derailleur either wanted to work in the largest 5 sprockets or the smallest 5. Yes, I was definitely pushing the limits of the gearing.

 

 

SOLUTION(s)

1. Removing the front derailleur, I added a ROTOR QXL/Q-Ring Shim ($15 from The Parts Shoppe). This shim (actually more of a wedge) measures 20mm tall x 9mm wide and 2mm thick at the top x 1.4mm thick at the bottom. It’s placed between the front derailleur hanger and the front derailleur. What is does is to tilt, or drop the rear of the derailleur cage so that the chain does not rub on the bottom of the cage.

Looking at the photo to the right, the shim is installed between ‘A’ & ‘B’. Line ‘A’ shows the vertical edge of the front derailleur hanger. Line ‘B’ shows the new angle of the front derailleur. Note that the front derailleur is rotated slightly counter-clockwise, which lowers the rear of the derailleur cage ‘C’ just enough so that the chain does not rub.

Note: This shim also helps fix many of the shifting issues encountered with QXL/Q-Rings. So, if you are running elliptical rings, this product is a MUST HAVE!!

1. A mechanic friend of mine told me about a product made by a company called Wolf Tooth Components. Wolf Tooth Components, located in Minnesota, is a group of hardcore cyclists always looking to make their bikes lighter, faster and more reliable. Since they are engineering and manufacturing specialists, they started creating much needed products that were not available. This is how the RoadLink came about. They too noted that for road bikes, the largest cassette cog that a ‘SS’ rear derailleur could handle was 28T. Moving up to a ‘GS’ rear derailleur, they could run a 32T. After this, the only option was to run a mountain bike rear derailleur, but the smallest large cassette cogs these MTB rear derailleurs handle is 40T. So, what if you wanted to run a 34T or 36T? Along came the RoadLink.

The RoadLink is a simple device that offsets the position of your 10 or 11 speed Shimano road derailleur to make it possible to run a wide-range cassette. The RoadLink is optimized for 11-36T and 11-40T.  It is an ideal solution for riders looking to convert their road, gravel, cyclocross, or commuter Shimano drivetrain bike to attain the simplicity and reduced weight of a single front chainring…and without giving up the gear range of a double.  It is also great for riders with double chainring bikes that want lower gearingfor those ultra-steep climbs.

 

INSTALLATION

See photos below for actual installation. Installation is a very simple task taking less than 5-minutes. To make this installation as easy as possible, before starting, I shifted the rear derailleur to the smallest cog which gave plenty of slack on the chain. If your chain is still tight, pop the chain off the front chainrings which allows maximum slack.

 

In PHOTO A, I am using a 5mm hex wrench to loosen the hex bolt which removes the rear derailleur from the derailleur hanger.

PHOTO B shows the rear derailleur removed. Note, the chain is still installed onto the drivetrain.

PHOTO C shows the installation of the RoadLink. I am using the same 5mm hex wrench as before, this time installing the RoadLink onto the rear derailleur hanger.

In PHOTO D, I am reinstalling the rear derailleur into the lower threaded hole of the RoadLink. Warning, when installing a rear derailleur, make sure that the B-screw clears the tab. Accomplish by tilting the rear derailleur clockwise while tightening the rear derailleur attachment bolt.

PHOTO E – Job well done! Now, just run the drivetrain through the gears, making a small tweak here and there to make the shifting perfect.

In the PHOTO to the right, look how much additional space was achieved between the derailleur and cassette. Actually a little too much, time to back off on the B-limit screw adjustment.

OUT ON THE ROAD

As stated earlier, without the RoadLink, the derailleur wanted to either shift in the larger gears or smaller gears, but not all of the gears. Adding the ROTOR shim and RoadLink, the rear derailleur shifts perfect in every gear. No rubbing, clinking or clanking trying to find a gear.

I’ve used the RoadLink with the fore-mentioned configuration for a month now. I got out on a couple of hammer rides where I was mainly in the 52/11-15, but mostly the Haute Hills of San Clemente. Our hill route picks hills of no less than 13% grade and peaking at 17.5% grade. For these rides, I’m in the 34/28-36 on the way up and 52/11-13 on the route down. This gives me a lot of shifting each ride and the bike performs flawlessly!

 

FURTHER INFORMATION:

EXPLANATION OF DERAILLEUR CAPACITY

As mentioned, the RoadLink moves Shimano 10 and 11 speed rear derailleurs to an optimal position for wide range cassettes.  What the RoadLink does NOT do is expand your derailleurs capacity, as that is a function of the derailleur mechanics.  What is capacity you ask?  Capacity is how much chain slack the derailleur cage can absorb measured in number of teeth.  To calculate the capacity you need for a given setup, use the following formula:

(Biggest Chainring – Smallest Chainring) + (Biggest Cassette Cog – Smallest Cassette Cog)

The derailleur capacity is a specified number that Shimano publishes and recommends not to exceed.

CAVEATS

• Double chainrings are only supported with GS (medium cage) rear derailleurs. You may need to change the front gearing so the rear derailleurs capacity is not exceeded.
• The RoadLink™ mounts only to standard derailleur hangers.
• The RoadLink™ is optimized for the 10 and 11 speed Shimano road derailleur geometry. It also works very well with 9 speed road groups, all SRAM groups, and Campy derailleurs. (Note: Campy works best with cassettes up to 11-36.
• SRAMs Exact Actuation road shifters (10s and 11s) are interchangeable with their Exact Actuation mountain derailleurs- which can easily handle a 36 or 40 (and, for one-by, are available with a clutch)- and the CX1 will go even bigger with a single ring.
• Triple chainrings are not supported (medium cage rear derailleurs cannot accommodate that big of a range).
• Direct Mount-native frames are not supported.
• Due to the lack of a clutch mechanism on Shimano road derailleurs, secondary chain retention (front derailleur or chain device) may be needed, especially for rough or off-road use.
• Due to variations in derailleur hanger geometry, chainstay length, chainring size, B-screw adjustment, and suspension configuration should all be adjusted accordingly.
• This 7.9mm max dimension is controlled by the Shimano spec, but a few derailleur hangers don’t meet the spec. Just file a little bit off the bottom “tang” of those derailleur hangers to install the RoadLink™.

SUMMARY

I have to rate this a full 5/5 stars. The design is as simple as can be, no moving parts to break and it works! Period! At $21.95, the cheapest and best solution for adding some gearing to your road bike.