Cervelo Aspero: Redshift Sports ShockStop Pro Suspension Stem

I have been hearing good reviews of this suspension stem from Redshift Sports, especially when used on gravel bikes. It is apparently very effective in dampening out small vibrations when riding on gravel, which improves comfort.

On my Cervelo Aspero, I am using wide and comfortable WTB Venture 47 650B tires, which are already pretty good. However, if I improve the comfort by lowering the tire pressure, it makes the bike more draggy, especially when riding on paved sections. There is a trade off between comfort and speed, when I adjust the tire pressure.

I am hoping to see if adding a suspension stem will improve the comfort further, without increasing the rolling resistance. The idea is that I can still maintain a good tire pressure of around 30 PSI for the front tire, which is the lowest that I can accept without it feeling too draggy. At the same time, the suspension stem will be able to absorb any bumps that actually travel up the fork, and dampen it before my hands feel it.

There are 2 versions of this stem, the standard ShockStop and the ShockStop Pro. The Pro version is lighter in weight, due to more machining and also uses titanium hardware instead of steel. The appearance also looks better on the Pro version. In my case, I value the improved appearance and lower weight, which is why I got the Pro version even though it costs more for the same performance.

Here it is! The Pro version.

It provides 10-20 mm of suspension travel in the stem. I wonder how it will feel?

It may look complicated, but the construction is actually quite simple and clever. This is the 80 mm version.

It is very important to follow the instructions carefully, to avoid damaging the stem or create any safety issue. This step shows how to remove the elastomers.

The elastomers can be changed to those of different hardness, to suit your body weight and your riding preference.

Here are the different combinations of elastomers which you can use, to customize the stiffness that you want.

There is a large pivot on the stem which rotates to absorb the bumps, while being dampened by the elastomers.

There is a gap to allow the front part of the stem to move relative to the steerer tube clamp portion.

This 80 mm stem weighs 226 grams, less than 100 grams more than the 80 mm PRO Vibe stem that I was using previously. Very acceptable weight increase for the comfort.

I can't use the stem straightaway, as the rise of the stem is wrong for me. It comes stock with the stem rising upwards, but I want to use it with the stem tilting downwards. In this case, I cannot just flip the stem and install it like conventional stems, as the suspension parts will be upside down.

What I need to do is to remove the internal elastomers and wedge, and install it upside down, so that I can use the stem with a downward tilt. Good chance to see how to assemble the internal parts.

The instructions state that to swap elastomers, the stem must first be clamped on a steerer tube, so that a pre-load can be added during installation. Instead of using the steerer tube on the bike, I made a tube of diameter 28.6 mm instead.

From my spare parts area, I placed an adapter of 28.6 mm --> 25.4 mm (used on the Bike Friday Haul-A-Day) over a 25.4 mm tube (from Litepro stems), creating this tube.

ShockStop stem clamped lightly onto this 28.6 mm diameter tube.

With the stem face plate removed. The elastomers and wedge needs to be flipped to the other side.

Extra elastomers of different hardness provided, along with a cool tool to remove the wedge.

The tool has two sides to it. One side is for removing the wedge, while the other side is used to install the wedge.

Use two of the stem bolts to fix the tool to the stem. Then, use the supplied bolt to pass through the red tool, and thread into the wedge. 

When you turn the bolt, it will pull out the wedge, much like a crank puller. Very clever.

Wedge removed! The stock elastomers used are of 60 and 70 hardness. I believe it is Shore A hardness, which is used to measure how hard an elastomer is.

All 5 of the elastomers, ranging from 60 to 90. By using a combination of these elastomers, a wide range of stem stiffness can be created.

In the next post, I will continue with the reinstallation of the elastomers, followed by some test riding comments.

Shimano XTR vs Deore XT vs SLX: 11-40T 11 Speed Cassette

This is probably an outdated comparison, as MTB cassettes have moved on to 12 speeds. However, I don't have the chance to compare Shimano 12 speed MTB cassettes, as I no longer have a MTB that can use these cassettes. The last 12 speed cassettes that I compared were the S-Ride and SRAM NX Eagle cassettes, which can fit on existing freehub bodies instead of XD or Microspline types.

Therefore, I can only compare the older but still popular 11 speed MTB cassettes. I have been doing a lot of road cassette comparisons, here is one of the few MTB cassette comparisons.

11 speed MTB cassettes are actually great for gravel riding, as the wide range is well suited for off-road riding, while the ratios are still close enough to use on-road without huge gaps. A prime example is the Cervelo Aspero gravel bike that I have, which is using a 1x11 speed drivetrain. Besides, 11 speed components are very common nowadays, so they are easy to find.

Today, this comparison is all about the 11 speed 11-40T cassettes. This is the smallest cassette that can arguably still qualify as a MTB cassette, as smaller ones like 11-36T are considered gravel or even road cassettes. To be honest, a 11-40T cassette is now more commonly classified as a gravel cassette, since it is one of the cassettes recommended for use with a GRX gravel groupset.

This comparison is between the XTR, Deore XT and SLX version of the 11-40T 11 speed cassette. As expected, the XTR version will be the lightest, but also the most expensive. I have not used the XTR 11-40T cassette yet, while the other two have been used on my bikes.

The Deore XT 11-40T cassette is used on the Bike Friday Haul-A-Day cargo bike, for a wide gear range. I am very happy with the gear range on that bike as it is spot on, and I don't require a lower or higher gear on that bike.

The SLX version was tested on the Cervelo Aspero, when I was attemping to make a super wide range 2x11 speed drivetrain with a 11-40T cassette. Unfortunately the Di2 version cannot support this wide range, but I believe a mechanical drivetrain can.

XTR CS-M9001 11-40T 11 speed cassette, with 4 separate spiders!

Deore XT CS-M8000 11-40T 11 speed cassette, with 2 spiders.

SLX CS-M7000 11-40T 11 speed cassette, with just 1 spider, and a spider-shaped spacer.

The focus for this post will be on the XTR cassette, as I have not studied it in detail before, unlike the Deore XT and SLX cassettes. I am interested to know how it differs in construction with the Deore XT and SLX version, allowing it to be so lightweight.

Biggest two sprockets (40T and 35T) of the XTR cassette are mounted on a 7-arm carbon fibre spider. Largest sprocket is aluminium, while the 35T sprocket is made of titanium.

Deore XT and SLX share the same design, as the last 3 sprockets (31T, 35T, 40T) sprockets are mounted on an aluminium spider. The 40T sprocket is made of aluminium, with the rest being steel.

Rear view of the XTR 7 arm carbon fibre spider, which looks pretty awful to me.

Rear view of the Deore XT/SLX aluminum spider. Looks better in my opinion.

Let's do a weight comparison of these three cassettes, before moving on to check out the XTR cassette in more detail. There is a big weight difference between these cassettes, which correspond to the big difference in prices.

XTR cassette weighs only 324 grams! This is because it has 6 titanium sprockets, 1 aluminium sprocket and just 4 small steel sprockets.

Deore XT cassette is quite a bit heavier, at 413 grams. Just 1 aluminium sprocket and 2 aluminium spiders.

SLX cassette is heavier still, with also 1 aluminium sprocket, but also just 1 aluminium spider. It means that all other steel sprockets are full sized and thus heavy.

Closer look at the XTR cassette, with the above mentioned 1 aluminum sprocket, 6 titanium sprockets and 4 steel sprockets.

Design of the spider, which is made of carbon fibre reinforced nylon (PA-CF). Spline is reinforced with an aluminium insert.

Rear view of the spider, which looks very bulky with the large surface area.

With 1 titanium and 1 aluminium sprocket, plus the carbon fibre spider, these two large gears weigh 117 grams. Although it is considered lightweight, it already accounts for more than 1/3 of the cassette weight.

Next two sprockets (27T and 31T) are made of titanium, also riveted to a carbon fibre spider. This time, a 6 arm design is enough.

Splines are also reinforced with an aluminium insert for strength. The CS-M9001 is a revised version of the original CS-M9000.

There are some holes on this carbon fibre spider, but it is blocked by the ribs running behind it (previous picture). Strange design.

This second set of sprockets weigh just 79 grams.

Here is the 3rd set of sprockets (21T and 24T, both titanium) on the aluminium spider.

Since the spider is aluminium, the splines are machined directly into the spider.

3rd set of sprockets weigh just 49 grams.

There is still a 4th spider for the 17T (steel) and 19T (titanium) sprockets! Even road cassettes don't use a spider to mount the 17T sprocket.

Being small means that only 5 arms are needed for the aluminium spider.

These two sprockets weigh 38 grams. I don't think there is much weight saving over a standard full steel 17T and 19T sprocket, since they are already quite small.

Finally, only 3 loose sprockets, the 11T, 13T and 15T. Extremely rare to find a cassette with just 3 loose sprockets, with the rest mounted on the spiders.

From this, I can see that the weight saving efforts applied to this XTR cassette is quite extreme, with so many spiders and so many titanium sprockets used. The best balance between cost and weight should be the Deore XT version, as it is more durable, a lot cheaper, with some weight penalty.

Some examples of alternative cassettes with the same 11 speed 11-40T are the Sunrace CSRX8, and the extreme KCNC version which is even lighter!

Shimano Ultegra R8000 vs 105 R7000 Brake Calipers

Although rim brakes are considered outdated compared to disc brakes, it is still available nowadays for those who want to save weight. A rim brake bike is roughly half a kilogram lighter than an equivalent spec hydraulic disc brake bike, depending on the grade of components.

Here is a quick comparison of the Ultegra R8000 caliper brakes vs the 105 R7000 caliper brakes. The Ultegra brakes are used on the Dahon MuSP, which still uses caliper brakes instead of disc brakes. On the other hand, the newly-acquired 105 brakes were supposed to go onto the United Trifold, unfortunately it did not fit. Not all upgrades are successful.

For other comparisons, check out the older posts.

Ultegra R8000 vs 6800 brake calipers

Ultegra 6800 vs 105 5800 brake calipers

Ultegra uses a lightweight plastic cable adjust barrel, and black coloured axles.

105, being a more low cost version, uses a traditional cable adjust barrel, with normal silver coloured axles.

Ultegra has the model number printed clearly in white, and the black axles can be seen here.

105 model number is molded together with the cast aluminium brake arm, which means it is not very visible.

Shimano logo printed at the side, as well as a nice anodised surface finishing.

105 version omits the Shimano logo, and uses a cheaper spray paint surface treatment. The area where the pivot nuts sit look a bit different as well.

The stamped steel stiffening plate on the Ultegra improves the rigidity of the brake caliper, making it more powerful.

105 does not have the stiffening plate, which makes it less rigid but also saves a bit of weight.

Cam roller on the Ultegra brake caliper improves the braking power.

105 also has the same cam roller, due to the same dual pivot design. Tiagra brake calipers do not have this roller.

Weight of a pair of Ultegra R8000 brake calipers, with pivot nuts (length unknown) is 362 grams.

105 R7000 brake caliper is 185 grams each, which means about 370 grams for a pair. But this does not include the pivot nuts, which probably add another 10-15 grams.

I think the biggest appearance difference is definitely the surface finishing, I prefer the better looking anodised surface finishing of the Ultegra brake caliper. There is also a performance difference, due to the extra stiffening plate in the Ultegra brake caliper. Lastly, the 105 calipers weigh about 20 grams more than the Ultegra version, which is not a lot.

I believe the brake pads are the same, just that the brake pad holders have a different surface finishing. Nothing exciting about this comparison, as I don't think Shimano is developing caliper brakes any more, with this probably being the last generation of high quality caliper brakes. Still one of the best in the market in terms of absolute braking power, although it comes at the expense of weight. After all, you need material to create stiffness, you just can't have good stiffness if you use thin cross sections.

In fact, the latest Dura-Ace and Ultegra groupsets are Di2 shifting and hydraulic disc brakes only, with no steel inner cable in sight anywhere.