Sunday, June 30, 2019

Bike Friday HaD: Ascent Bikes Custom Wheelset and Schwalbe Marathon Tires

As you may already know, I am starting to build a cargo bike. One of the special requirements for a cargo bike is a set of wheels that can endure higher loads, since that is the purpose of having a cargo bike. The bike frame and the wheels have to carry an additional passenger or items, and so will need to be rated for the extra weight.

Standard bike wheels will not do the job, as they are not designed for heavier loads, therefore we need to look for a set of durable wheels. BMX wheels have stronger rims and many more spokes, due to the high loads exerted on the wheels when jumping off ledges or doing tricks. However, standard BMX wheels cannot support an 11 speed cassette as the hub is usually limited to single speed gears.

Since I want to run an 11 speed cassette on the cargo bike, I have to get a custom built wheelset that can support an 11 speed cassette, with strong rims and more spokes.

Ascent Bikes allow lots of customization of their bikes and wheels, and you can pretty much specify any component you want on the bike, down to the colour of the bolts or the type of stickers on the wheels. Still, this request for a custom built, extra strong wheelset is not common, but they are willing to help me out with this.

My request is quite straightforward. To have a 20" wheelset with 32 or 36 spokes, using a hub with 100/135 mm OLD, and compatible with Centerlock brake rotors. It should be all black in colour (rims, hubs, spokes, spoke nipples) for a clean appearance.

For the rims, 20" BMX rims were used, as they are strong and wide enough, and comes in 36 hole variants. Straight gauge 2.0 mm spokes and brass nipples were used for strength, no lightweight aluminium spoke nipples here. Finally, the request for a Centerlock brake rotor compatible hub pretty much limits the choice of hubs, and the dependable Deore XT M8000 hubs were chosen.

All black wheelset! Lots of spokes for extra strength and rigidity.

Deore XT M8000 hubs with Centerlock brake rotor mounting.

Extra wide BMX rims

Black brass spoke nipples

2.0 mm straight gauge spokes used for extra strength.

Rim height is about 17 mm, with no rim brake track.

Internal rim width is 24 mm, which is really wide.

External rim width is 29 mm. This also means that any tire that I install on these rims will end up being wider than the nominal claimed width.

Includes high quality, wide Schwalbe rim tape.

Front wheel weighs 703 grams (including rim tape).

Rear wheel weighs 866 grams (including rim tape).

The total wheelset weight, inclusive of rim tape, is 1569 grams. This is actually lighter than I expected (1.7 - 1.8 kg), which is awesome. In fact, it is lighter than the stock Dahon D7 wheelset that comes with the Dahon Boardwalk, but is much stronger.

Deore XT QR axles, which are heavy but strong. Not a place to compromise on strength for a cargo bike.

With the custom built, heavy duty wheelset ready, the next important choice is the type of tires. The tires also have to be strong enough to withstand the additional weight of a cargo bike, so lightweight, narrow tires are out of the question. Which leaves us with tougher, wider but also heavier touring tires. There are quite a few different types of touring tires, which makes it difficult to choose.

In the end, I chose the narrowest, lightest touring tire that I think I can get away with, and that is the Schwalbe Marathon. Taking into account the permissible load on each tire, the type of tread pattern (smoother for lower rolling resistance), and the puncture resistance, this was the choice. The standard Marathon does not have very high puncture resistance (like the Marathon Plus), but it is much lighter and rolls better, and it is a risk that I am willing to trade off. No matter what, it will be more puncture resistant than the tires on my other bikes.

Pair of Schwalbe Marathon tires! Equipped with reflective strips for additional visibility at night.

Closer look at the logo and model name.

This is the narrower variant, at just 1.5 inches wide. It would prove to be the correct choice, as shown later when installing the rear derailleur and cassette. The E-Bike ready label doesn't mean much here.

Rather deep treads, for extra grip over rough and loose terrain. The centre line has a continuous unbroken surface, which should mean lower rolling resistance and lower noise.

Recommended tire pressure is a wide range, from 55-100 PSI. For heavier loads, it is recommended to set the pressure at the higher end of the range for less chance of a pinch flat.

Each tire weighs 557 grams, a far cry from the 239 grams for Schwalbe Kojak tires. The heavier duty Schwalbe Marathon Plus tires are even heavier!

As for inner tubes, the 40-406 tire size is in-between inner tube sizes. Either SV6 or SV7 tubes can be used.

In the end, I chose the wider but heavier SV7 inner tubes, as the wider rims mean that the tire would end up being wider than 40-406.

Tires and inner tubes installed on the wheelset!

This wheelset looks strong and durable, ready to be installed on the cargo bike! At that time, I was still waiting for the frameset, and started gathering all the necessary components for the bike.

Saturday, June 22, 2019

Ascent Bikes Road Crankset

For my new bike building project, I will be running a 1x11 speed drivetrain. As such, I will require a front single crankset, using a chain ring with narrow-wide teeth for chain retention.

I have already built a few bikes with front single drivetrains, and I usually use a Shimano road crankset. The road crankset comes as a front double setup, so I will remove both the outer and inner chain ring, and install a third party narrow-wide chain ring.

Examples can be seen here, on the Dahon MuEX, the Dahon MuSP, and the Crius AEV20. There are more examples, but these are the main ones.

As you can already tell, I like the Wolf Tooth Drop Stop chain ring, as it comes in a large variety of chain ring sizes, and most importantly, it has 4 arm variants that can be fitted to newer Shimano road cranksets (Dura-Ace 9000 series and newer). I have never ever had a chain drop from the Wolf Tooth chain ring, that is how good it is.

In summary, I would usually get a Shimano road double crankset, and remove both the chain rings. Then, choose an appropriately sized Wolf Tooth chain ring, to match the crankset (4 arm or 5 arm). Finally, get some chain ring bolts for a front single setup, where the colour can be customized to add some bling to the bike.

However, this strategy is expensive, as Shimano road cranksets are quite pricey, since we are paying for the Hollowtech forging crank arms, plus the Hollowglide chain rings. The differences between the different grades of Shimano cranksets can be seen here.

After that, the chain rings are not used, and just kept in the storeroom, in case I want to restore the front double crankset one day (almost never). To add on, the Wolf Tooth Drop Stop chain ring is expensive too!

In order to reduce the cost and also prevent wastage (unused chain rings), I started to look around for good quality, dedicated front single cranksets, with narrow wide chain rings. Of course, it has to be available at a reasonable price, and also a reasonable weight.

After doing a comparison between a few different brands, I found this in-house crankset by Ascent Bikes, which is a dedicated front single crankset. It is Shimano road bottom bracket compatible (24 mm diameter spindle, 68 mm BB spacing), and uses a narrow-wide chain ring. The appearance is pretty decent, with a matte black, sandblasted finish that matches most bikes. The weight is around the same as an equivalent Ultegra+Wolf Tooth setup (more details below), but the price is about 1/3 of it!

Let's take a detailed look at this front single crankset by Ascent Bikes.

Overall look at the crankset. Direct mount chainring with 6 arm design. Hollow spindle visible from the drive side, similar to mountain bike crankset appearance.

Weighs 629 grams, with a 44T chain ring. Just a few grams heavier than an Ultegra crankset + Wolf Tooth chain ring setup.

I was quite surprised at the weight of this crankset, as it is lighter than it looks. Normally, for this kind of non-hollow crank arms, it will weigh much more, at 700 grams or more. Ultegra-level of weight, at 1/3 the price? I'm not going to complain about that!

Closer look at the right side crank arm. Design is simple but functional, which is fine with me.

Right side crankarm + 44T chain ring + 4 mounting bolts weigh 412 grams. The direct mount chain ring design can also be seen here.

How it looks with the chain ring removed. Crank arm shape is simple with no strong character lines.

Hollow aluminium spindle is press-fitted to the drive side crank arm. 

Rear side of the crank arm is heavily sculpted to remove material and reduce weight. Looks a bit weak, but I will probably not be strong enough to flex it significantly.

Splines on the crank arm to match the chain ring, for the direct mount design. The spline design is different and so cannot be interchangeable with direct mount chain rings from other brands.

Splines on the non-drive side of the aluminium spindle, where the non-drive crank arm will be fixed to.

With the chain ring and chain ring bolts removed, the drive side crankarm + spindle weigh 288 grams.

4 x chain ring bolts weigh just 8 grams.

44T direct mount chain ring. This size is chosen to provide the gear range that I need. There is some offset between the centre mounting area and the teeth, in order to achieve the correct chain line.

Spline design on the chain ring.

Narrow wide teeth design on the chain ring.

Made of aluminium alloy 7075, with T6 heat treatment. From what I know, this grade of aluminium can be machined easily, which makes it popular in chain rings, seat posts and stems.

Another look at the narrow wide teeth on the chain ring.

44T chain ring weighs 117 grams. 

Left side (non-drive side) crank arm.

Also heavily sculpted at the back for weight reduction. Forged for extra strength, as compared to being made by casting process. 

Left side crank arm weighs 212 grams, which is about 20 grams more than an equivalent Ultegra left side crank arm.

Aluminium crank arm fixing bolt is unique, and weighs 6 grams. Tightens to the spindle using an Allen key.

Just a random shot of the crank arms, with the chain ring removed. If the chain rings and crank arms are stored separately, it can save a lot of storage space as they can all be flat-packed.

In a later blog post, I will be installing this Ascent Bike crankset onto the bike, and evaluate the performance and riding feel. What I will check is how stiff the crankset feels, as compared to the other cranksets that I have.

For now, I am happy with how the crankset looks and weighs. With an Ultegra-level weight at 1/3 the price, it looks to be a really good alternative for a dedicated front single crankset.

Tuesday, June 11, 2019

Polygon Cozmic CX3.0: SRAM GX Eagle Gripshift Setup

The Polygon Cozmic CX3.0 MTB gets yet another modification, so that I can try out different components! This time, it is the less common Gripshift that is made by SRAM. Most MTB shifters on the market are trigger type shifters, that are operated by thumb/thumb (SRAM) or thumb/finger (Shimano).

The benefits of trigger shifters is that you can keep a firm grip on the handlebars during shifters, as you only need to use your thumb and/or finger during shifting. However, the disadvantage is that multiple gear shifts take a bit longer as the shift lever needs to be pressed multiple times.

As for Gripshift, the whole hand is used to rotate the grip on the shifter, which also allows multiple gear shifts in both directions. The downside is a less solid grip on the handlebar as the hand needs to loosen the grip for shifting.

Most of the Revoshifters (Shimano) you see on the market are on entry level bikes, and also kids bikes, as it is easier for kids to shift compared to trigger shifters. They are also many other China and Taiwan brands which makes these shifters, such as Microshift. On the other hand, SRAM markets these Gripshift (SRAM) as a mid to high end product, which is completely different from other companies. Let's see how it works compared to other shifters!

I got the SRAM GX Gripshift and the rear derailleur as a set, and installed these new components onto the Polygon MTB. I had to move the whole SRAM NX groupset to another bike, so I had to swap the cassette to the S-Ride cassette as well.

The handlebar grips are included with the SRAM Gripshift as well, which allows it to blend and match nicely with the shifter. Overall length of the shifter + grip is quite long.

Still using the good old Deore M615 hydraulic disc brakes.

As there is only 1 right side shifter, the left side handlebar grip that is included is a full length normal grip. Might as well use it to complete the look.

As the overall length of the right side shifter + grip is long, the brake lever had to be shifted inwards. Subsequently, in order to maintain left and right symmetry, I also had to move the left side brake lever inwards. The ergonomics has been changed, from two-finger braking to one-finger braking. I will need to get used to this as I have not really used one-finger braking like the pros.

SRAM GX Eagle 12 speed rear derailleur. Looks slightly nicer than the SRAM NX RD, but the difference is not very big.

S-Ride 11-50T, 12 speed cassette back on the bike!

1x12 speed drivetrain. S-Ride cassette, SLX crankset, SRAM GX Eagle RD, unknown 12 speed chain (which came with the S-Ride groupset).

After testing, I found that the shifting action of the SRAM GX Gripshift is quite light! The shifting stroke is rather short, and the shifting force is quite low, which makes it easy to shift gears. Compared to other shifters, this one is definitely better.

However, it is best suited to urban usage only, as there is no need to have such a firm grip on the handlebars when riding in the city or park. When riding off road, I found that having to relax my grip on the handlebars to shift is not ideal, especially when going downhill. For serious off road riding, I would still prefer to use trigger shifters.

In summary, it is an interesting setup, and I would continue to use this setup, until the next experiment comes along!