Sunday, April 5, 2020

Cervelo Aspero: 700C vs 650B Wheel Size Comparison - Part 1

Before I tried gravel riding, there was no need to consider wheel size or tire width. Basically, a road bike setup means using a 700C x 25 or 28 mm tire. The tire diameter or width is just what it is, there is no concern if the tire ends up a bit wider or narrower than claimed, or even a bit bigger or smaller in diameter.

However, when I first used a gravel setup on the Canyon Endurace, I found that depending on the tire width, the tire diameter will also be affected significantly, especially if the tire width differs a lot. This can be a problem, as a bike is designed around a nominal wheel size, with only a small variance allowed. If the wheel size differs too much, it affects the geometry of the bike.

Crank clearance with the ground will be reduced if the tire diameter is smaller. Also, the trail of the bike will be reduced with a smaller wheel size, which can cause instability.

If the tire diameter is larger, the usual problem is frame or fork clearance, but the bigger issue is a slower handling bike due to larger trail from the larger tire size. This may be good or bad depending on your desired purpose.

In this case, it is difficult for the bike frame designer to optimize for a single wheel size, if it needs to accommodate a wide range of tire diameters, from small 700C x 23 to large 700C x 43 mm, for example.

Which is why the Cervelo Aspero has a Trail Mixer on the fork which allows the trail value of the bike to be adjusted, depending on the wheel size and also your preference for a more agile or more stable bike.

I will not go through the explanation again on why I chose 650B wheels and tires, you can read about it in my previous posts.

DT Swiss G 1800 Spline DB 25 Wheelset
Panaracer GravelKing SK 700C x 32 Tires

Hunt 650B Adventure Carbon Disc Wheelset
Panaracer GravelKing SK 650B x 43 Tires

Before I compare the new 650B wheelset, I will compare the wheels used previously on the Canyon Endurace. That would be the Reynolds Assault carbon wheelset for the road setup, and the DT Swiss G 1800 wheelset for the gravel setup. Both are 700C wheels.

The Reynolds Assault wheelset is equipped with Continental GP4000 700C x 28 tires, but the actual tire width is almost 32 mm. This is due to the relatively wide internal rim width of 21 mm.

The DT Swiss G 1800 wheelset is equipped with Panaracer GravelKing SK 700C x 32 tires, with an actual tire width of 35 mm. This rim has an internal width of 24 mm.

Rim diameter looks almost similar, with the gravel wheelset being just a little big larger.

Close up look at the different tire tread patterns.

Tire diameter is very similar.

In this case, if the tire diameter is almost the same, swapping between the wheelsets will not cause significant differences in ride geometry. This was the case on the Canyon Endurace.

Moving on to the new Hunt 650B wheelset, the rim diameter is smaller, but the tire will add back some of the diameter by having a taller sidewall. A 700C rim has an outer diameter of 622 mm, while a 650B rim has an outer diameter of 584 mm. This is a difference of 38 mm, which means 19 mm on either side. If a 650B tire is to have the same outer diameter as a 700C tire, the side wall needs to be 19 mm taller, which is a huge difference.

650B x 43 mm tire on the left, 700C x 32C tire (actual 35 mm) on the right. The diameter difference is quite obvious.

The 650B wheelset on the right has a smaller diameter, as seen from the difference in axle height. This will also be the difference in bottom bracket or crank arm clearance.

Another view showing the difference in tire diameter.

Using a long thru axle to align the centre of the hubs, the difference in radius can be measured more accurately.

650B tire has a gap with the ground. Multiply this gap by 2 and you get the diameter difference.

Using a 10 mm Allen key as a gauge, there is still a tiny bit of clearance. I would say that the gap is about 11 mm.

Other than the diameter difference, there is a big tire width difference as well. The wider 650B tire on the right has 5 rows of small knobs instead of 3.

43 mm width on the left, versus 35 mm (actual) width on the right. This 8 mm width difference is quite obvious.

There is some difference in sidewall height, as the 650B tire on the left will have a taller side wall as it is wider. The height of the brown sidewall area is about the same, but the black sidewall area is much taller on the 650B tire.

Finally, let's also compare the 700C road wheelset with the new 650B gravel wheelset. These are the two wheelsets that I will use on the Cervelo Aspero. I will explain more about the road and gravel setup in a later post.

Hunt 650B wheelset on the left, for gravel riding. Reynolds Assault 700C wheelset on the right for road riding.

Significant difference in tire diameter between these two wheelsets.


Another view of the different tire diameter. Despite the wider tire width, the 650B tire does not add enough tire height to come close to the 700C tire diameter.

Difference in axle height, which is about 8 mm.

Big difference in tire width and tread pattern. 32 mm tire width vs 43 mm tire width.

Comparison of the tire sidewall height. The 650B tire is taller with much more volume, but not enough to make up for the smaller rim diameter.

In summary, here are the tire diameters as measured, and also the difference in BB to ground distance (which is calculated as half the difference in tire diameter).

Continental GP4000 700C x 28 (actual 32): 693 mm diameter
Panaracer GravelKing SK 700C x 32 (actual 35): 699 mm diameter
Panaracer GravelKing SK 650B x 43: 677 mm diameter

On Cervelo Aspero (Size 51)
BB to ground distance for Continental GP4000 (700C x 28): 268 mm
BB to ground distance for GravelKing SK (700C x 32): 271 mm
BB to ground distance for GravelKing SK (650B x 43): 260 mm

The differences between the 700C road and 700C gravel tires are not so big, while there is a big difference between the 700C road and 650B gravel tire. What does this mean?

Swapping from the 700C road wheelset to the 650B gravel wheelset will lower the bike by about 8 mm. That is 8 mm less crank arm clearance. Not sure if pedal strike will be an issue, as it has even lesser ground clearance compared to my other bikes.

On the plus side, a lower centre of gravity will help in cornering and descending at speed. A smaller tire diameter also means a lower trail value, which increases agility. Is increased agility good or bad for a gravel bike? This is up for debate, as increased agility can allow you to tackle twisty trails more easily, but also make a speedy descent less stable.

Regardless, the proof of the ride quality will require actual riding. Whether good or not, I will have to use the tires to see if it is suitable for my usage.

From left to right: GP4000 28 mm, GravelKing 43 mm, GravelKing 32 mm

The 650B wheelset is the junior here, having a smaller diameter than the other two.

This concludes the first part of this comparison, which is between these three tires. Later on, in Part 2, there will be an additional tire added to this comparison, stay tuned!

Sunday, March 29, 2020

Polygon Cozmic CX3.0: Sunrace MZ90 11-50T 12 Speed Cassette

Just a couple of months after I changed the rear derailleur and shifter on the Polygon Cozmic CX3.0 MTB to XTR, I decided to change the cassette as well. It is not possible to change to a Shimano 12 speed MTB cassette, as the Microspline freehub is needed. This means that a new rear wheel is needed.

I didn't want to spend money to upgrade the 26" rear wheel to have a Microspline freehub, as 26" wheels are considered obsolete in the MTB world. Although it still rides fine, I would rather spend money on getting a new MTB frame with 29" or 27.5" wheels.

Why would I want to change the S-Ride 12 speed cassette? That is because it has some flaws, which I hoped a better cassette would solve. For example, the shifting performance is not ideal when paired with the XTR 12 speed shifter and rear derailleur, as I think the spacing between the sprockets is not Shimano compatible. It does work OK when paired with the S-Ride 12 speed shifter.

The second reason is because the chain tends to derail from the sprocket during backpedaling. This happens in the lowest (largest) 2 sprockets, when the chain line is quite extreme. I have tried other bikes with a full Shimano 12 speed MTB groupset (XTR or Deore XT or SLX) and they don't have this backpedaling issue.

As Shimano does not make a 11-50T 12 speed cassette, I will have to look to other brands for 12 speed super wide range cassettes. SRAM Eagle 12 speed cassettes are also not compatible with my MTB, as a XD driver is needed on the rear hub. Therefore, I decided to get the Sunrace 12 speed MTB cassette to try out.

The Sunrace MZ90 12 speed cassette has a sprocket size of 11-50T, which is really wide, and it is compatible with standard freehub bodies. Although I don't get the 10T sprocket, I am fine with it as 11-50T range is already very big.

11-50T Sunrace MZ90 12 speed cassette. Looks pretty high end!

Weighs just 525 grams, quite a lot lighter than the S-Ride or the SRAM NX cassettes.

Gear steps: 28-32-36-42-50T. Big step from 42T to 50T. The 42T and 50T are made of aluminium for lower weight.

Gear steps: 11-13-15-17-19-21-24-28 and so on. Pretty standard gear steps.

Largest 4 sprockets are riveted together onto this massive red aluminium spider.

The largest 2 sprockets are cantilevered far out from the spider, enabling 12 sprockets to be squeezed onto the standard freehub body.

Next 3 sprockets (21-24-28T) are riveted onto the second spider.

Nothing special of note here.

All the 12 gear sprockets!

The red spacers are made of aluminium, which are usually only used on higher end cassettes.

There is even a free gift of the RD dropout extender with extra long B-tension bolt, in case you want to use your existing rear derailleur that is not rated to reach the large 50T sprocket.

Sunrace MZ90 11-50T 12 speed cassette assembled onto the bike! The red coloured spider is really eye catching.

Still looks enormous no matter how many times I see it.

Silver coloured sprockets match quite nicely with the XTR rear derailleur.

At gear 3, the RD cage is at its lowest point.

At the lowest gear (gear 1), the RD cage is fully stretched as shown.

Latest picture of the bike, with the Sunrace 12 speed cassette being the newest component on this bike.

The Sunrace cassette is a significantly big step up in quality, compared to the S-Ride cassette. First, the shifting performance is improved, as I think the gear spacing is more or less compatible to Shimano.

Also, there is no longer any chain drop from the sprocket, when I backpedal at the lowest 2 gears. This is due to some clever shaping and design of the sprocket teeth which helps to hold the chain onto the sprocket.

This Sunrace MZ90 12 speed cassette is not cheap (around SGD $110 from Taobao), especially for a cassette that is not from Shimano or SRAM. However, it is considered the best of the rest, and it seems to work well with these Shimano components. Overall, I would say it is a good upgrade, especially for older bikes that do not have the Microspline or XD freehub bodies.

Saturday, March 21, 2020

Fnhon DB11: Assembly Completed

The Fnhon DB11 disc brake folding bike is finally completed! This project was started because I didn't want to ride rim brake bikes any more, which is why I decided to change my Dahon MuEX which uses V-brakes.

With a new disc brake compatible frameset, disc brake compatible wheels and a new hydraulic disc brake system, this new folding bike is going to be a nice upgrade over the previous one. Without further delay, let's take a detailed look at all the new components on this Fnhon DB11.

This is Part 2 of the assembly process, to continue from Part 1 where it was started.

Handlebar setup, with new hydraulic brake levers, but the same old Ergon GP1 grips.

Neat cable routing, with only 2 hydraulic hoses visible at the front of the bike.

However, I noticed that the handlepost is tilted to one side. As you can see from the picture below, when the front wheel is vertical, the top of handlepost is offset to the right side due to it not being straight enough. The whole handlebar is thus slightly slanted to the side, with the right side being slightly lower than the left side.

It is quite annoying, but it can only be solved by changing out the whole handlepost. I might do that later on, but it is not urgent. Riding is still OK.

Handlepost is visibly tilted to the right side, causing the handlebar to be tilted and offset towards the right side.

I have another bike with a flat handlebar Di2 setup, and that is the Bike Friday Haul-A-Day cargo bike. It is almost the same as the Dahon MuEX setup, with a Firebolt Di2 shifting switch and Di2 Digital Display. Let's do a comparison between these two handlebar setups.

Bike Friday handlebar in the foreground, and Fnhon DB11 handlebar just behind it. The Fnhon DB11 handlebar is located just a bit higher up.

Both are Di2 systems, but the brake lever, shifting switch and Di2 display are of different models.

Toseek carbon saddle mounted to the Litepro seat post.

Drivetrain mostly transferred over from the Dahon MuEX, except for the Dura-Ace Di2 rear derailleur. Chain ring bolts changed from red to black to match this bike.

Junction B of the Di2 system is located on the seat tube, hidden behind the chain ring.

For me, this 48T Wolf Tooth chain ring is actually over sized, as it was meant to be used with the smaller 406 wheels on the Dahon MuEX. On this new Fnhon DB11 bike with larger 451 wheels, the gearing will increase by roughly 10%.

Gear Range with 11-32T cassette and 48T chain ring:
Dahon MuEX with 406 wheels: 30 - 87 gear inches
Fnhon DB11 with 451 wheels: 33 - 96 gear inches

I don't need such high gearing on this folding bike, as I am unlikely to ride so fast. If I want to revert to the previous gearing, I will need to use a smaller 44T chain ring on this bike with 451 wheels. However, Wolf Tooth chain rings are quite expensive, and so I will just use what I have for now.

Actual chain weight, after being cut to the correct length for this bike. This is a new HG701 11 speed chain.

Lightweight titanium quick release axles are used to save a bit of weight. Note the multiple cable ties needed to route the Di2 wire neatly from the frame to the rear derailleur.


Fnhon DB11 folded. The folding method is neat and relatively compact, with no parts sticking out oddly like on some folding bikes.

Unfortunately, I have now encountered a problem, after folding the bike. The front metal plate and rear magnet are unable to stick to each other as they are not aligned properly.

The front metal plate (adjustable) and rear magnet cannot stick to each other as they are not aligned.

The adjustment range is insufficient to let the magnet stick to the metal plate. Probably a frame design error.

Easiest way is to extend the metal plate, by using a steel bracket that is long enough to reach the magnet. Same idea that I used 10 years ago, to install the Magnetix system on the Dahon Eco 2.

View of the front brake caliper and 160 mm disc rotor, together with the DIY metal plate.

View of the rear brake caliper and 140 mm disc rotor.

The size difference between the rotors can be seen when they are put side by side.

The Magnetix system now works, with the longer metal plate. Problem solved!

Fnhon DB11 folded.

With the handlebar folded in between the wheels, the folded package is smaller.

Fnhon DB11 disc brake folding bike completed! Note the various 3M rubber pads stuck on the frame to prevent rubbing between the parts when folded.

Nothing colourful here, with a black-on-black colour scheme.

Here is the full part list with the weight of the individual components. Don't ask me how much it costs as it will vary greatly depending on where you buy them from.

Outdoor picture of the Fnhon DB11

Looks really nice!

I am really pleased with how this project turned out, as the bike looks beautiful. I used some high end and expensive components, such as the XTR brake levers and calipers, and also Dura-Ace Di2 rear derailleur. However, these can easily be substituted for more affordable components, or even a mechanical 1x11 speed drivetrain.

The brakes are powerful, as expected from XTR brake components and small wheels. One finger braking is enough, which makes it really effortless to control the bike. Due to the relatively narrow tires and small wheels, the steering is a bit sensitive, compared to using the wider Kojak tires. It is not an issue as I am used to riding small wheeled bikes with more sensitive steering.

Probably the only downside to this new bike, compared to the Dahon MuEX, is the additional weight, mainly due to the heavier frame and wheels, plus the added weight of the hydraulic disc brake system. The Dahon MuEX weighed 8.4 kg without pedals, while this Fnhon DB11 weighs 8.9 kg without pedals as shown above on the part list. It is an addition of 0.5 kg that is quite a big amount, despite the weight reduction efforts of using a lighter saddle, handlebar, brake components, etc.

If you want to build a lightweight folding bike, a disc brake version will not work. However, if you are willing to add a bit of weight to have a much better braking performance, disc brakes will work really well. It is not necessary, but I really prefer to use hydraulic disc brakes, since almost all my other bikes are already using them, except for the Dahon MuSP.