In order to match the super wide ratio Garbaruk 11-50T 11 speed cassette that will be going on the Cervelo Aspero gravel bike, I need a compatible rear derailleur.
Given the limits of Shimano Di2 11 speed drivetrain (which is needed for GRX Di2 11 speed), there is currently no compatible rear derailleur. The MTB Deore XT Di2 RD-M8050 can go up to a maximum of 46T, and it is very similar to the GRX Di2 RD-RX817 which I am using.
Therefore, a third party rear derailleur cage is needed to have compatibility with a larger cassette. That was why I need this Garbaruk rear derailleur upgrade kit to make a 11-50T cassette possible with the GRX Di2 11 speed drivetrain.
There are specific rear derailleur cages to match different rear derailleurs, so I made sure to get the correct version to match my GRX Di2 rear derailleur RD-RX817. There is no compatibility with the RX815 version (for 2x11 speed).
New larger pulleys and cage are sold separately, but I needed both.
These may not be genuine Garbaruk cage or pulleys, as they are relatively cheap. Can you spot the typo errors?
To be clear, I bought the Garbaruk cassette separately from the cage and pulleys. The cassette was ordered and shipped directly via the Garbaruk website, while the cage and pulley was from another source. The price difference for the cage and pulleys were quite big when compared to the Garbaruk website. Nevertheless, the quality was good as you can see below.
Aluminium inner and outer cage
Inside view of the cage
2 spacers are used to join the two halves together, before attaching the pulleys.
Engraved words indicate that this cage is compatible to GRX Di2 rear derailleur (RX817).
Garbaruk cage on the left, vs the stock RX817 rear derailleur cage on the right.
Although the pulley to pulley distance does not differ a lot, the Garbaruk cage is a lot longer overall to accommodate the larger tension pulley. This is necessary to increase the chain capacity of the rear derailleur.
Next, to determine compatibility, the fixing point on the cage needs to be compared. There are many dimensions which determine if the cage is compatible or not. From my previous lesson with the Fnhon Ultegra Di2 12 speed, where I attempted to install a TiParts rear derailleur cage onto the Ultegra Di2 rear derailleur, most of the dimensions and design will need to match to ensure compatibility.
Position of guide pulley and stopper looks similar
Similar P axle length and design, which is great news.
Pulley to pulley distance on the stock GRX RD-RX817 is 77 mm. That's in between the Ultegra R8050 and R8150 rear derailleurs.
Garbaruk pulley to pulley distance is 103 mm, slightly longer than the Ultegra R8150 rear derailleur.
Stock GRX cage weight is 34 grams
Garbaruk cage weighs the same at 34 grams, despite it being longer.
So far it looks like the Garbaruk cage will be compatible to the GRX rear derailleur, but I will only know for sure after I install it successfully.
To complete the upgrade kit, I also needed larger pulleys to match the larger cage. Here are the pulleys by Garbaruk.
New aluminium pulleys by Garbaruk. Tension pulley is large at 16T, while the guide pulley is small at 11T.
The new guide pulley remains at 11T, same as stock, to ensure clearance with rear derailleur and cassette. Tension pulley is much larger than the stock 11T.
Stock guide pulley vs new guide pulley. Very different looks despite both being the same 11T size.
Stock plastic pulleys weigh 22 grams
New Garbaruk aluminium pulleys weigh less at just 19 grams, due to extensive cutouts to reduce weight.
The 16T Garbaruk tension pulley has narrow wide teeth, which is surprising. Guess it helps to prevent chain drop from the pulley.
I also noticed that the 16T pulley has teeth that are off centre. You can see more protrusion on this side of the bearing.
On the other side, it is almost flat with no protrusion at the centre. The teeth is biased towards this side. Since there are no instructions, I will figure out the ideal direction later.
On the left is a spare pulley bolt that I have, but it is a lot shorter than the GRX stock pulley bolt on the right.
Short pulley bolt is just 11.9 mm long
GRX pulley bolt is 14.1 mm long
If I use the short pulley bolt, it is not long enough for proper thread engagement.
In the next post, I will write in detail the installation process of fixing the Garbaruk cage and pulleys to the GRX rear derailleur.
No comments:
Post a Comment
Every comment is moderated before publishing due to spam bots. If you don't see your comment yet, it is likely that it is currently being reviewed. Thank you for your patience!