Showing posts with label Gravel. Show all posts
Showing posts with label Gravel. Show all posts

Saturday, September 7, 2024

Cervelo Aspero: Super Wide Range 1x11 Speed Setup

Here are pictures of the Cervelo Aspero gravel bike with the latest super wide gear range upgrade! More pictures and links below.


Clean and fresh cassette

The cassette is even larger than the 160 mm diameter brake rotor!

Lots of cutouts on this lightweight cassette.

As the cassette size has increased from 42T to 50T, I need to add a few links to the chain. Easiest way is to use a second quick link to add a section.

Still quite a distance to the cage stopper at the rear top gear setting, after adding 4 links.

Adjusting the distance between the guide pulley to the 50T sprocket teeth.

Good clearance between the cage and the spokes even at the lowest gear.

Position of chain and rear derailleur at the rear top (11T) condition.


Looks like the chain length can be increased, since there is still some distance before the cage stopper is reached.

Position of chain and rear derailleur at the rear top (11T) condition.

Position of chain and rear derailleur at the rear top (11T) condition.

Position of chain and rear derailleur at the rear low (50T) condition.

Cage looks very stretched!

Position of chain and rear derailleur at the rear low (50T) condition.

Position of chain and rear derailleur at the rear low (50T) condition.

Position of chain and rear derailleur at the rear low (50T) condition.

Chain only engages 3 teeth on the guide pulley when in the 50T sprocket, due to the cage angle.

Although the chain length seems to be a bit too short, the shifting and engagement all works fine. In this case I think it is OK to just do some test rides to see if the chain really needs to be lengthened or not.

There is no problem with the Garbaruk cassette at all, as I am able to shift normally up and down all the gears. Also, backpedaling while on the largest 50T sprocket is possible as well, without causing the chain to drop off the sprocket. This happened on a S-Ride 11-50T cassette long ago on the Polygon Cozmic CX3.0 MTB.

Full bike view with the large 11-50T cassette!

With the new 50T sprocket, what I gain is actually just one more lower gear of 20.5 gear inches. Seems like a lot of effort for just one more gear!


Full specifications of the Cervelo Aspero after this upgrade.

The Garbaruk cassette weighs 154 grams less, while the GRX Di2 with Garbaruk cage weighs 1 gram less. Discounting a few grams added back for the longer chain, there is still a significant weight reduction of around 150 grams!

It is rare that an increase in gear range is coupled with a reduction in weight, but this is all due to the lightweight Garbaruk cassette.

With an extra low gear, it is much easier to ride up steep slopes, as I can pedal smoothly instead of having to push extra hard on a higher gear.

I'm really happy with this Garbaruk upgrade, as it allows me to enjoy a super wide gear range on the Cervelo Aspero, while retaining the excellent shifting ergonomics and performance of the GRX Di2 groupset.

Cervelo Aspero: GRX Di2 Rear Derailleur with Garbaruk Long Cage

On the Cervelo Aspero gravel bike, my latest modification is to expand the gear range, up from the existing 11-42T cassette to a larger 11-50T cassette.

I have already received the Garbaruk 11-50T 11 speed cassette, and the rear derailleur cage upgrade kit. Now I will install the upgrade kit onto the stock GRX Di2 RD-RX817 rear derailleur, and hopefully everything fits well!

Stock GRX Di2 RD-RX817 rear derailleur before changing the cage.

Rear derailleur undergoing surgery, with a cage transplant in progress.

I had previously transplanted a Deore XT M8000 long cage onto this GRX rear derailleur before, so this is not new to me. That previous modification was a useful experience that made this upgrade so much easier.

Garbaruk 11T and 16T pulleys installed onto the Garbaruk cage!

It seems to fit well, no problems detected so far.

Stock GRX pulley bolts are used, as they are of the correct length.

Cage transplant complete with new pulleys!

No problem with pulley clearance, since the new guide pulley is the same 11T size as the stock guide pulley.

GRX Di2 RD-RX817 rear derailleur with Garbaruk long cage

Modified GRX Di2 rear derailleur with Garbaruk cage weighs 320 grams, 1 gram less than the stock GRX rear derailleur!

With this Garbaruk cassette and cage modification, the weight was actually reduced while the gear range has increased. More details in the next post!

Cervelo Aspero: Garbaruk Long Cage for 50T Sprocket

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.