Cervelo Aspero: 650B and 700C Gravel Wheelset Comparison

Since I now have both a 700C and 650B wheelset for my Cervelo Aspero gravel bike, it is a good chance to do a side-by-side comparison. This will be useful for those who cannot decide between a 700C or 650B gravel wheelset.

As the wheels are different, the weight comparison is merely for reference. The Hunt 650B Adventure Carbon Disc wheelset is one of the best 650B wheels around, and is also very lightweight. On the other hand, the DT Swiss G 1800 wheelset is a basic aluminium gravel wheelset that is rather heavy.

650B wheel on the left, with brown sidewall WTB Venture 47 tires.

Both are using 11-42T 11 speed MTB cassettes.

650B wheel with WTB Venture 47 tires have a diameter of 681 mm.

700C wheel with WTB Byway tires have a diameter of 698 mm.

As you can see, there is a diameter difference of about 17 mm between these two wheelsets. It is expected, and this size difference will mean a different axle-to-ground height, and also BB ground clearance. The ride characteristic will also be slightly different, which is where the Trail Mixer position may be used to adjust the ride feeling.

Axle centre differs by about 8.5 mm, which is about half the diameter difference of 17 mm.

700C wheelset is noticeably larger than the 650B wheelset.

Very different tire treads. Smooth centreline on the 700C Byway, and grippy treads on the 650B Venture 47.

Tire width is different, as a smaller 650B tire can have a wider tire compared to a 700C tire, without frame interference.

Venture 47 measures true to size at 47 mm, on a 24 mm internal rim.

Byway measures 37 mm on a 24 mm internal rim, smaller than the claimed 40 mm width. I'm OK with this width as it is midway between the 27.5 mm GP5000 road tire and the 47 mm Venture 47 tire.

The 700C Byway has a tire width that is 10 mm narrower than the 650B Venture 47, which may or may not be a good thing. I'm hoping that the smooth centreline on the Byway will give me low rolling resistance on tarmac.

The height of the tire sidewall is very different. The black areas are about the same height, but the 650B tire has an additional brown sidewall height which adds a lot to the air volume inside the tire.

DT Swiss G 1800 front wheel with Byway tire and rotor weighs 1600 grams, which is quite heavy. Also partly because I am using inner tubes.

Hunt 650B carbon front wheel with Venture 47 tire and rotor weighs less, at 1448 grams. Although the tire is heavier, the carbon rim and tubeless setup saves quite a bit of weight.

DT Swiss G 1800 rear wheel with rotor and cassette weighs 2224 grams, which is also heavy.

Hunt 650B rear wheel with rotor and cassette weighs less at 2036 grams.

700C wheelset weight is thus 3824 grams, while the 650B wheelset weighs 3484 grams. If I used a high end carbon rim for the 700C wheel, plus tubeless setup, the final weight will be lighter than the 650B wheelset, as the 700C tires are usually lighter.

Main Differences:

1) 700C tire width is 10 mm narrower than the 650B tire.

2) 700C tire diameter is 17 mm larger than the 650B tire.

3) 700C wheelset is 340 grams heavier than the 650B wheelset.

4) 700C tire has a smooth centreline tread, which should make it roll smoother on tarmac.

It is nice to compare the specifications, but the final test is how well it rides on the road. For this 700C gravel wheelset, I need it to ride well on the road, while also being wide and grippy enough to handle some light gravel.

After extensive testing on the road and gravel, I found that this 700C gravel wheelset is rather disappointing. My expectation was smooth rolling on tarmac, due to the smooth centreline in the middle of the Byway tire. However, I could still feel a significant amount of drag, and it feels pretty slow to accelerate or cruise. In fact, my 650B wheelset feels even faster, even though the Venture 47 tire has a more knobbly tire on it. It could be due to the heavier DT Swiss G 1800 wheelset, instead of the Byway tire. Hard to conclude unless I put the Byway tires onto a lightweight set of 700C carbon gravel wheels to compare again.

As for light gravel riding, the Byway tire also does not perform very well. Due to the smooth centreline, it does not have sufficient grip. Compared to the 650B tires, I have to slow down a lot more on loose corners, to avoid sliding during cornering. This makes it a relatively poor gravel tire as well.

I just came across an article reviewing this exact tire, and the conclusion was the same as what I discovered. The rolling resistance was quite high, which is unexpected since there is a smooth centreline that is supposed to reduce rolling resistance.

In all, this Byway 700C tire is neither fast rolling on road, and also not grippy enough for proper gravel riding. I'm sure there are some good 700C gravel tires out there, but this is not the one. Unfortunately this 700C tire does not provide the characteristics that I want, so it is back to the 650B gravel wheelset on my Cervelo Aspero gravel bike.