Testing to Find the Fastest Bicycle Wheel Hubs

Posted on 17 Comments

The aerodynamic performance of wheels often grabs the headlines and the marketing budget but the reality is the hubs and the bearings within them will have more of a performance differential for the average cyclist. As an example, the power differential between wheels of an equivalent depth at speeds of less than 35km/h will only be 1-2W, the difference in bearing friction can easily exceed that.

Wheel hubs and freehubs account for around 60% of the rotational friction in a bicycle drivetrain. The remaining friction is from the pedal bearings, bottom bracket and pulley wheels. The total amount of friction is small but a cost effective marginal gain.

The term rotational drag has been used of late to describe the amount of power required to spin a wheel up to speed. This loss is a significant aerodynamic loss of about 25 to 30 percent. Rotational drag is not the same as frictional drag which comes from the mechanical components.

Wheel Hub Design methodology

There are a several engineering considerations to be made when designing hubs which have been discussed below

  • The most obvious is the choice of bearing type. The vast majority of hubs use 6000 series ball bearings which are deep groove. A notable exception are Shimano and some Campagnolo/Fulcrum wheels which use cup and cone bearings. A cup and cone bearing is a type of angular contact bearing. A cup and cone bearing will always have more friction than a radial bearing because of an axially oriented contact angle. A loose cup and cone bearing allows for fairly slack manufacturing tolerances.
  • The bearing material (ceramic or steel) is often credited with lowering the friction in a hubset. The reality is the seal and choice of grease will have more effect.
  • The axle size determines the friction torque from the bearings. Axle sizes of between 10mm and 17mm are common on bicycle hubs. The smaller axles will always have lower frictional torque because the moment lever is shorter, the negative effects are the wheel hub will have more flex and the bearings will not last as long.
  • Machining accuracy, a lot of hubs are manufactured in Taiwan by forging aluminium 7075 alloy and then machining bearing landings afterwards. This is a standard process but it can be riddled with quality control issues. Having bearings that are misaligned due to slack jigs and holes that are too tight due to worn cutting tools will severely hamper friction levels.

The chart below shows the friction loss through hubs which were loaded. These tests results have some limitations

  • They do not take into account Road Vibration
  • A sample size of one for each hub set does not take into account any natural variation
  • Some of the hubs had completed an unknown mileage, they were checked for vibration to ascertain any bearing fault frequencies.
  • The power figure has some factors for calculation and it’s advisable to use this as a relative reference rather than an absolute figure
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Upgrading Wheel Bearings

It is not cost effective to replace OE bearings straight from the factory unless the rider requires the ultimate in marginal gains. It is more advisable to wait until the bearings have worn out first and then retrofit.

Conclusions

Generally speaking, the Hambini recommended hubset to use would be the Carbon-TI. These have low levels of friction, are well made and use decent quality bearings from the factory. The Miche Primato hubs are a good budget option but the small axle diameter is not favourable in the longer term despite having the overall lowest friction, it should be noted that the test example had retrofitted bearings so the exact figure from the factory may be higher or lower. The angular contact Shimano hubs do quite badly in this test because the contact angle lends them to high levels of axial load, these wheels will be extremely stiff and predictable when cornering but the trade off is the higher linear friction.

In the longer term, bearings will wear out and for this reason, Shimano hubs are not recommended unless the cyclist is willing and able to carry out regular maintenance. The bearing surfaces are costly to replace and are a proprietary component.

17 thoughts on “Testing to Find the Fastest Bicycle Wheel Hubs

  1. Sachin – Was looking at this graph on Weight Weenies but have to ask here because you are banned. Do you think the bitex hub set would perform similarly to Carbon Ti if retrofitted with low friction NTN or SKF bearings?

    1. Yes BUT some Bitex hubs use non standard sizes so you end up having to use cheap no name branded bearings. Carbon ti use 6000 series on all of their hubs so you can always get them in any brand.

      1. Which Miche hub was tested?

          1. Primato Syntesi?

          2. it was just primato.

  2. hello
    after 14years i wanted to replace the bearings in my AmCl RD205. After unmounting the bearings i meassured the bearing landings (15267)
    freewheel outer: 25,92mm
    freewheel inner: 25,96mm
    hub inner: 25,96mm
    hub outer: 25,98mm
    while a document from ntn said the tolerance need to be M5, so 25,986 – 25,995mm.

    My question: if i press good bearings in this small landings, will i have some benefits?

    What can I do to make the landings wider without special equipment?

    1. That’s too small, you’ll find the bearings start to rattle quite quickly

  3. I’ve seen a set of 2017 Zipp 202’s with 77/177 hubs at a good reduced price. Unfortunately I’ve found several poor reviews regarding the hubs, rear wheel play and flange failures. What do you think?

    1. From experience, I’d say the hubs were rubbish.

      1. Thank you. Your no nonsense approach is so refreshing. I’ve introduced your videos to some of my friends in Canada and they really love you. Only if you have time: I have always run alloy rims with standard Campag, Mavic or Hope hubs but in my advancing years I fancy something a bit more exotic. Saw some ZED Ultalite carbon clinchers 1200g from a UK company and was wondering if there were any questions I should be asking about the hubs in particular?

  4. What do you think about the DT180 hubs? Where do you think they would stack up? Deciding between them and the Carbon-Ti X Road Hub. Thanks!

    1. I would get the carbon ti

  5. Should low tier Taiwanese bearing manufacturers such as TTN, or NBK be avoided at any cost?

    1. personally, I would avoid them but each to their own. Their technical support is often crap.

  6. Hambini, thank you for sharing your work on this topic. Your resources have been valuable as I’ve thought about making some upgrades and as I’ve begun to spec out my first custom build.

    TLDR: – How do engagement points factor into hub speed, and should it be considered in hub selection?

    I’ve seen and heard a fair amount of chat about a hub’s efficiency due to the number of its engagement points. I’ve seen this discussed as the number of teeth, pawls, or combination thereof in a hub’s ratchet system.

    If memory serves, I read that a high number of engagement points was developed for benefit in mountain biking’s hilly environment. However, it has clearly become a feature that commands premium pricing in road cycling as well. Example: DT350 has an 18T ratchet while DT180 has 54, and it’s a common upgrade(?) for people to change out their 18T DT350 to either a 36T or 54T ratchet.

    Does the number of points of contact meaningfully contribute to how fast a hub is for a typical urban or suburban road riding environment? Any clear benefits one way or the other for the average enthusiast rider versus a competitive racer? If it’s generally true that having more engagement points is better for performance, is there any downside whatsoever, such as maintenance or durability?

    1. Road hubs vs MTB hubs are a different animal. You don’t really need the very small angular catch on a road bike because the gear ratios are much longer so only a fraction of turn on the pedals will engage the ratchet on a road bike. You also don’t have the on off power loading on a road bike.

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