Shimano XTR MT900 vs Deore XT MT800 Centerlock Brake Rotors

I recently bought some new rotors, and it gives me a chance to do a quick comparison. The new rotor is the XTR MT900 rotor, which is very similar to the Deore XT MT800 rotor. I previously installed the MT800 rotors on two different bikes, the Canyon Endurace (gravel wheelset) and the Fnhon DB11 folding bike.

At first glance, these rotors look very similar, with only a different colour on the cooling fins. Let's take a closer look to see if there are any other differences.

Black paint on the cooling fins are claimed to help dissipate heat faster. Theoretically it is true, but does it make a discernible difference?

XTR MT900 rotor

Side by side comparison of MT900 vs MT800 rotors.

The cutouts are the same, and the shape of the cooling fins are the same as well.

View from the rear

XTR MT900 rotor has big cutouts at the back of the aluminium spider for weight reduction.

Deore XT MT800 rotor spider has an extra round holder, which is not used in this case. It is probably for the E-Bike type of rotor which has a magnet installed here for the speed sensor.

Weight of MT800 160 mm rotor, only 106 grams. 

Add 8 grams for the aluminium lockring, and it weighs 114 grams.

MT900 rotor also weighs the same

Same lockring, thus same weight. 114 grams for 160 mm rotor (MT900/MT800).

As seen from the weight comparison, MT900 and MT800 rotors weigh the same. However, they are a bit lighter than the Dura-Ace RT900 rotors. You can also check out the comparison to the older RT99 rotors.

Trying out the MT900 rotors on the wheels.

Putting the rotors on the Hunt gravel wheelset to see how it looks.

Here is the RS770 wheelset as used on the Focus Paralane, it currently uses Dura-Ace RT900 rotors.

Changed to the new XTR MT900 rotors. Visually there is not a big difference.

Shown as installed on the Focus Paralane front wheel.

Rear wheel with XTR MT900 rotors.

Rotors changed from RT900 to MT900. Not a big visual difference.

The conclusion is that the MT900 and MT800 rotors are very similar, with only the colour of the fins separating it. They weigh the same and performance would be the same as well.

Ultimately which rotor you choose will depend on your budget and also the appearance. Some people like how the black cooling fins look, but it is also more expensive.

Cervelo Aspero: Front Single Conversion - Part 2

With the front single drivetrain components prepared earlier, now I can replace the current front double drivetrain with a front single drivetrain on the Cervelo Aspero. 

Last time, when I went off-road riding on the Aspero, there were some damage to the chain stay. That was due to insufficient clearance between the chainring and the chain stay for mud. After that I pasted a layer of protective film to prevent future damage.

Unfortunately, some time after that, there was another incident which again caused damage to the chain stay. This time, the chain derailed during a downshift on the chainrings, during an uphill climb. I'm not too sure how it happened, as it was the first time the chain derailed on the Aspero, it being a rare event for me.

Fortunately, I felt a weird sensation when the chain came off, and I immediately stopped pedaling. This avoided further damage to the chain stay.

Protective film damaged by the derailed chain.

After the incident where the chain derailed, I did not take any action, as the damage had already been done. I left the half-peeled off protective film on the chain stay for quite a while, as I was lazy to remove the crankset and replace the protective film.

Now, since I will be replacing the crankset, I finally took the chance to check out the damage and replace the protective film.

Ouch! It doesn't look pretty, but I'm glad the protective film took the brunt of the damage from the dropped chain, as it could have been much worse.

Pasting a new layer of protective film, after removing the torn parts and cleaning the frame.

It's like magic! The scratches are mostly covered up by the transparent protective film.

The next step is to install the new crankset with the new chainring. Since it is a front single crankset, and with a relatively small 38T chainring, I expect the chain stay clearance to be more than the 2 mm found on the previous Dura-Ace 50/34T crankset.

Checked with an Allen key, the clearance is 3 mm. Not as big as I thought.

View from the top. OK clearance, but thought it would be more than 3 mm.

Next step is to replace the current Sunrace 11-36T cassette with the SLX 11-42T cassette onto the Hunt 650B gravel wheelset. Replacing the 11-36T cassette with a larger 11-42T cassette, and dropping from two to one chain ring will result in an overall decrease in gear range. That's because the new cassette does not have a gear range that is wide enough to replace the double chain rings. Gear ratios to be compared at the end of this post.

11-42T cassette next to the 11-36T cassette.

Front single drivetrain completed! Here it is shown at the lowest gear, with the rear derailleur cage fully stretched.

SLX CS-M7000 11-42T cassette with GRX Di2 RD-RX817 rear derailleur.

Adjusting the B-tension on the rear derailleur, such that the guide pulley is as close to the cassette as feasible. This will help to ensure good shifting performance at the top gears (Eg. shifting between 12T and 11T).

The chain is now at the 11T top sprocket, with the rear derailleur cage fully retracted.

Still enough chain capacity, as the chain is still some distance away from the guide pulley.

Maybe not as much margin as I first thought, as the stopper pin is already quite close to the stopper.

Here it is shown at the middle of the cassette.

The 105 R7000 left crankarm with 4iiii power meter was also transferred over, along with the Deore XT M8020 pedals. This does not match the Ultegra crankset on the right, but I don't mind.

Small clearance between the 4iiii power meter and the chain stay. Similar to that with Dura-Ace crankset.

Testing the new drivetrain out on some real gravel

Looking good with the new front single crankset!

Love the new front single drivetrain, as it is simpler to use. It's awesome to test the drivetrain and tires on freshly laid gravel.

Overall bike picture with the front single drivetrain, it suits this Aspero gravel bike well.

By making this drivetrain modification, there is a change in overall bike weight and also the gear range. Let's take a look at the differences.

Weight comparison of the front double vs front single drivetrain that I used.

By comparing the weight of the components that I have changed, I found that I saved a grand total of 1 gram! Perhaps it is a few grams more if I include the front derailleur Di2 wire that I removed, but in the end it is a very small difference. Most of the weight reduction up front has been added to the larger cassette at the back.

Other than the weight, the gear range has also been changed. Here is a comparison before and after.

Previous gear range with 50/34T crankset and 11-36T cassette: 

25.5 - 123 gear inches over 15 unique gears.

New gear range with 38T chainring and 11-42T cassette: 

24.4 - 93 gear inches over 11 unique gears.

By converting to front single, I lose the top 3 gears which I almost never use when gravel riding, as it is just too high for me. Since I no longer use this Aspero for fast road rides, this is acceptable. Also, there is a big gear step from the 13T to the 11T sprocket, which is unavoidable on all the larger cassettes.

On the other hand, with a small 38T chain ring and a low 42T sprocket, I do get an easier low gear which is always welcome, especially when climbing steep off-road slopes.

In summary, changing from a front double to a front single drivetrain has no weight savings, while it retains most of the gears that I use during gravel riding. I will be using the 650B wheelset and tires as my primary wheelset on the Aspero, since it is now a gravel bike. A gravel bike can basically go anywhere, as it transits from smooth road to park connectors to gravel tracks easily.

Great 1x11 speed drivetrain!

Front single chain ring for simplicity

Wide range 11 speed rear cassette

Cervelo Aspero: Front Single Conversion - Part 1

Ever since I built the Focus Paralane to be my primary road bike, this Cervelo Aspero no longer needs to be a dual purpose road and gravel bike. As such, I have more freedom to change out some of the components, to better suit its new purpose as a pure gravel bike.

One of the differences of the gravel bike from a road bike is the gearing required. On a road bike, you will need a higher gear ratio due to faster speeds on the road, and also closer gear steps if you need to optimize your cadence during group riding.

On a gravel bike, you are usually riding slower, more often on unpaved roads than paved roads, thus the gearing can be lower. Also, there is less group riding on gravel, therefore cadence control is not so important. You can basically pedal at your own preferred cadence and speed, thus bigger gear steps are acceptable.

I considered swapping out the crankset, from the Dura-Ace R9100 50/34T to the GRX RX600 46/30T combination. This will lower the gearing to make it more suitable for gravel riding, while still keeping closer gear steps.

However, I found that the RX600 46/30T crankset is really heavy! As it uses solid crankarms instead of hollow crankarms, it weighs a lot more than the Dura-Ace crankset.

Right side of the RX600 46/30T crankset weighs 536 grams.

Left crankarm weighs 276 grams, excluding the plastic crankarm fixing bolt.

This gives a total crankset weight of 812 grams, which is even heavier than the 105 crankset. In comparison, the Dura-Ace R9100 crankset only weighs 610 grams, which is more than 200 grams lighter. With such a big weight difference, I could not accept this change.

Therefore, I decided to go for a front single drivetrain, which simplifies the drivetrain setup and might reduce a bit of weight at the same time.

As mentioned in the other post on the Focus Paralane, I decided to swap the cranksets between the Focus Paralane and the Cervelo Aspero. The Dura-Ace crankset thus goes onto the Paralane road bike, while the Ultegra crankset and 38T Wolf Tooth chainring will go onto the Aspero gravel bike. This is better as the smaller chainring is suitable for gravel riding. This right side crank arm plus chain ring weighs just 396 grams, a whole lot lesser than the GRX RX600 right side which weighs 536 grams.

Ultegra R8000 crankset with 38T Wolf Tooth chainring. With multi-coloured chainring bolts for decoration.

With a front single crankset, I will need a wide range cassette at the back, in order to get enough gear range. Unlike with the front double drivetrain, there are much lesser restrictions as to what cassette I can use, since there is no front derailleur or total chain capacity to worry about.

In this case, I can use the dedicated GRX Di2 rear derailleur, RD-RX817 which is designed for front single drivetrains. Check out the detailed comparison between the rear derailleurs for front double or front single drivetrains. The RD-RX817 is basically very similar to the Deore XT Di2 MTB rear derailleur.

RD-RX815 for 2x11 speed on the left, RD-RX817 for 1x11 speed on the right.

With the front single crankset and front single specific rear derailleur prepared, the next component we need is a wide ratio cassette. The widest Shimano cassette available is actually a 12 speed MTB cassette, with a range of 10-51T. However, it requires a Microspline freehub, while there is also no 12 speed Di2 system from Shimano.

Therefore, what I need is a 11 speed MTB cassette. I can choose between the ratios 11-40T, 11-42T, and 11-46T. I have used the 11-40T cassette on the Bike Friday Haul-A-Day cargo bike, and the 11-46T cassette on the Polygon Cozmic MTB.

A wide ratio is nice, but a huge gear step jump is still not preferred. The 11-46T cassette has a wide gear range but also a big gear step from the 37T to the 46T. I did not like this, which is why I decided to use a smaller 11-42T cassette now instead. The low gear difference between a 11-40T and 11-42T cassette is small at just about 5% difference.

11-42T cassette can be found on the SLX CS-M7000 cassette.

It has one large aluminium spider, with the rest being full spline sprockets. The Deore XT version has two aluminium spiders for lower weight.

7 sided aluminium spider joins up the 3 largest sprockets.

3 largest gears are 32T, 37T, and 42T.

A spider spacer is used to help support the sprocket during sideways bending loads.

This 11-42T cassette weighs 478 grams, which is not lightweight. 

Although weight is saved from the removal of one chainring and front derailleur, it is added back by the use of a wide ratio cassette. I don't expect to save much weight by converting from front double to front single drivetrain, let's check out the weight comparison later. This SLX cassette is much heavier compared to the Sunrace 11-36T cassette, the Ultegra 11-34T cassette, or the Dura-Ace 11-30T cassette.

Finally, with the removal of the front derailleur, the front derailleur mount on the frame can be removed as well. It is not necessary, but since the replacement cover is available, I decided to change it. This cover was provided with the frameset.

Cover with front derailleur mounting on the left, blank cover on the right. The screws used are the same.

Used the blank grommet to replace the previous grommet which has a hole for the front derailleur Di2 wire.

Blank cover and rubber grommet installed! Now it becomes 1x ready. See how it looked like previously.

Here is the first part of the front single conversion, where I have gathered all the parts, ready for bike modification. To be continued!