Wheel Comparison: 650B vs 700c

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Wheel Comparison: 650B vs 700c

In the gravel cycling scene, 700c sized wheels have been dominant. Sure, we see the occasional 26 inch wheel out there, but by and large the traditional road wheel size of the last 30 plus years has been the size most often used for gravel road riding. However; as with mountain biking, we are seeing some 650B wheels and tires being used now. Obviously, we are testing a set of these wheels and tires, (seen HERE), and we have seen a question arise about the differences between the wheel sizes themselves. So, this post will aim to compare 650B and 700c wheels and give you, the reader, some information with which you can use to decide which might be better or interesting to try for yourself.

WTB

The Raleigh Tamland Two with 650B wheels and tires.

Tamland Two

The Raleigh Tamland Two with traditional 700c wheels and 40mm tires.

In a traditional 650B conversion, where the 650B tires are swapped into a 700C road bike, most authorities agree that a fat, 42mm-47mm 650B tire will approximate a 700 X 28-30mm wheel and tire’s diameter. This means that a swap between wheels on a bicycle that fits both would result in a very similar bottom bracket height, gear inch figures, and trail geometry. You might gain a more comfortable ride using 650B wheels and tires, since the increased volume in the tires might allow you to use a lower pressure than with the 700X 28mm-30mm tires. Traction is another area where this swap might make sense for the rider, as a bigger, wider contact patch results when a lower pressure 650B tire is used over that of the 700c X 28-30mm tire.

However; most gravel going bikes are using tires much wider and with much more volume than a 700c X 28-30mm tire. What are the differences between these 700c X 35-40mm wheels and tires and 650B X 47mm wheels and tires? Wheel diameter is a very noticeable difference, but there are other factors to consider when thinking about making the swap from 700c to 650B on your gravel machine. So, following are a few things that may help you sort through the benefits and negatives in your specific case when looking at the switch.

Wheels

The 700c X 40mm Panaracer Gravel King SK on the left and the 650B X 47mm WTB Horizon on the right

Comparison: What you are looking at above are two wheels on a board which has been leveled using a liquid filled level and on which are the two wheel sizes in question. I chose to use two tires more closely related in volume and width rather than diameter, so keep this in mind. The Panaracer Gravel King 40, as we tested here, was found to be more of a 42-43mm tire based on user feedback and our own testing. This compares most favorably with the 47mm Horizon, which is right at 47mm on the Velocity Aileron rim. Both tires are set up tubeless in this demonstration and both set to the same air pressures. Following are the measurements for diameter.

  • Gravel King/HED Ardennes+ Wheel: 28 1/16th” or 70.27cm diameter
  • WTB Horizon/Velocity Aileron Wheel: 26 7/8th” or 68.26cm diameter

Note: 1 inch = 2.54cm

We can see then that the overall diameter difference is a bit more than 3/4’s of an inch, or 2.01cm. Considering that a rider can use a lower pressure with the wider 650B tires, that difference could be larger by a small amount, however, we will assume similar differences for this comparison. Diameter has an affect upon your trail figure. That is a definition of how far your steering axis is ahead of your front axle. For reference, please review the information at this link and try to understand the concept. Many believe this can help determine how a bicycle will handle. I am merely trying to show that the differences in diameter do have an affect upon this trail figure, and subsequently may take the handling of a certain bicycle in one direction or the other. Either more stable or more unstable. It will be up to you to decide what is desirable.

In the case of the Raleigh Tamland Two, we can see that by using the stock spec figures given by Raleigh, the Tamland Two should have a trail figure of 66mm. If we use the Panaracer Gravel King size in this formula we get a number of 67mm. Now if we plug in the numbers using the Horizon wheel we get a figure of 62mm. The difference in trail between the Panaracer Gravel King 40mm tire and 700c wheel versus the 650B Aileron/Horizon 47mm wheel is therefore approximately 5mm. This should mean that the Horizon/Velocity wheel is slightly less stable than the Panaracer/HED wheel on the same bicycle. NOTE- A bicycle with the lower number will be less stable than the same bicycle with a front end geometry that results in a larger figure which is typically understood to be more stable.

Wheel

How does this information translate to the “real world”?

So, does this play out or matter at all in the real world of riding? In a word: yes. However; there is a lot more to it than a simple “yes” answer. I have a long and varied background in using several different trail figure set ups on several different types of bicycles. I ran a test in 2008 using eight different forks on a single bicycle, trying to keep all the other variables the same, to see, amongst other things, what trail did to the way that bicycle handled. In short, the results showed that a human being is an amazingly adaptable creature, and trail figure differences, while greatly affecting how a bicycle rides, can be adapted to, for the most part, by most humans. What that means is, you can tune your handling to your tastes.

In this instance, using the Raleigh, I was aware immediately that the 650B set up was more nervous, twitchy, and required a bit of acclimation. However; that sensation went away after about five miles, and only has occasionally reared its head since then. Unless you are looking to load the front end of your bike with a rack, or some other means of carrying stuff, this probably is of little import to this discussion, but it is something to consider in the overall concept of switching from 700c to 650B for gravel roads.

Other Considerations:

With the switch from the 700c wheels to the 650B wheels on the Tamland, I found a few other things that were notable, or that may be something you should make note of if you are considering a swap to 650B wheels and tires.

  • Clearances: The big benefit of going to 650B is for the width and volume of that wheel size and tire size. Unless your bike has room for 40mm tires or slightly bigger now, you may want to make a special note of this and carefully measure the space in your frame for big tires. The wider, more voluminous tires, like the WTB Horizon, will require more room, but affect your geometry the least. You can use a radius measurement based on my diameter measurements above to start out with, but some research may be required on your part to ultimately figure this out.
  • Momentum: The experiences I have had with 650B mountain and road wheels seems to point to characteristics that are different than I have experienced with 700c based wheels. My experiences seem to line up with many others. In short, the 650B wheel seems to spin up faster, but it also loses momentum faster than a 700c wheel that weighs similar and with a similar tire mounted. This can be seen as a benefit for some, but others will see it as a negative. It is up to you to decide which it is for you.
  • Gearing: Smaller wheels will result in a slight lowering of your gearing range overall than it was with larger diameter wheels. Again, this can be compensated for with changes in chain rings, or you might want to stick with what results in your specific case.
  • Computers: The old style of computers that do not rely on GPS, but on an impulse from a magnet on your wheel, will not read the same with a switch from 700c to 650B. This will only be a hassle for those who want to switch from one wheel size to the other on a regular basis.
  • Tire Selection: While there are a lot of 700c sized, gravel class tires available now, there are not a lot of suitable 650B models out now. Not only is the selection of gravel road suitable 650B tires slim, but getting a tire replaced in the wilds may prove to be an issue for some folks.
  • Bottom Bracket Height: With the slight decrease in diameter of 650B wheels, bottom bracket height will be lowered if you swap from 700c gravel wheels to 650B wheels. You may want to check out your current bottom bracket height and make sure that you do not end up with pedal strikes due to a lowered bottom bracket.
  • Weight: In the case of the swap I performed, there was a slight decrease in weight with the 650B wheels versus the 700c set that came off the bike, but this may not be the case in every instance. The differences are close enough that one may actually gain weight going to a 650B wheel set depending upon where you are coming from with your 700c set.
WTB

The wider tire, bigger volume, and resulting low pressure use opportunities are some reasons you may want to go 650B.

Conclusions:

I found that the 650B wheels had some attractive characteristics. One of them was that I can run ridiculously low air pressures. Think low as in mountain biking low. I have gone down as low as 22psi front/27psi rear, and have ridden two hours of rough, loose gravel with no ill effects. The reason for testing the depths of low pressure is that I am thinking that the same benefits mountain bikers enjoy with wide tubeless tires can be enjoyed by 650B wheeled gravel cyclists as well. Those would be comfort, increased traction, and some amount of flotation in looser road conditions. All this with little to no penalty in rolling resistance or perceived effort at the pedals. On harder roads and chip seal, these wheels are like cheating, the ride is that smooth and comfortable. I would tour on a set of these wheels in a heartbeat.

On the other hand, I could always feel that I was pedaling more with the 650B wheels versus a set of  700c X 38-40mm wheels and tires. Momentum can be an important thing on looser gravel, or softer terrain, and in these cases, I feel a 700c wheel set has a bit of an upper hand. That said, it is hard to argue that a 650B and fat tire set up tubeless does not have a better ride feel than anything 700c X 40mm or so.

Besides those things, I feel a smaller diameter wheel is a bit less stable in terms of getting knocked off line, or in terms of lateral stability on loose gravel, than a 700c wheel and fat gravel tire. This may have more to do with the Horizon tire’s smooth file tread and round carcass profile than it does with its diameter. Still, there is that lingering feeling at times that you are on a slightly more skittish wheel. I suspect I would completely become immune to this after several weeks of riding 650B exclusively.

Now it will be up to you to decide whether or not this wheel size deserves more of your attention. Look for more specific comments on the Velocity wheels and WTB Horizon 47mm tires coming up soon here.

Note: The component parts of these wheels were sent to Riding Gravel by the various brands/manufacturers for test/review at no charge. We are not being bribed, nor paid, for this review and we will strive to give our honest thoughts and opinions throughout.

Discuss and share your questions or thoughts about gravel bikes, gear, events and anything else on the Riding Gravel Forum

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21 Responses to Wheel Comparison: 650B vs 700c

  1. Tom July 8, 2016 at 4:06 pm #

    Great info. What is the best way/place to check if my bike/frameset has clearance for wider 650B tires? Thanks.

    • Daniel July 9, 2016 at 5:27 pm #

      WTB has a page on their website saying what frames work with 650b.

  2. Guitar Ted July 8, 2016 at 11:03 pm #

    Tom: You could take the radius of the wheel I measured as a guide, so 34.13cm, and measure that distance out from your axle center line to a point along and roughly parallel to your chain stays. The point where you see 34.13cm from the axle is going to be where the outside of the tire will be. At a point roughly where the tire would be at its widest back toward the axle from that point is where you would want to see at least 55-57mm between the chainstays.

    If this doesn’t make sense, you can take your bike to your local shop and ask them to measure it up for you.

    That’s the best I can do in this format for you. Hope that helps.

    • Mike G February 6, 2017 at 8:48 pm #

      Hi Ted,

      Thank you for your information….. I bought the Torker EM 50 that you once commented briefly about…. Candidate for 650 B Wheels? Comes with 700×45 Standard. Can’t find BB measurements but am assuming since Raleigh owned this company at one time and it works with the Tamland that it would work with this bike and I could fit a beefier tire as well. Your thoughts?

      • Guitar Ted February 6, 2017 at 9:17 pm #

        @Mike G- Typically bottom bracket drops are not very deep. I would think you would be okay, but I cannot say with any certainty. I do know that a Twin Six Standard Rando, with 75mm BB drop, will work with these wheels/tires. I would be very surprised to find out that the Torker model you specify has a deeper drop than 75mm.

        But, there is a chance.

  3. Daniel July 9, 2016 at 5:28 pm #

    This is a great article Guitar Ted. Answered a lot of questions. Thanks

  4. shiggy July 11, 2016 at 8:32 am #

    If you are going to carry a front load you want low trail. My bike has ~42mm. Not twitchy. Agile. Stable. On any surface.

  5. Guitar Ted July 11, 2016 at 3:46 pm #

    @shiggy: But if you are not considering anything for front loads, and just want to look at doing this conversion for the wider tires and comfort, then getting a slightly more “twitchy” or less stable is a concern folks should be considering.

  6. Kris July 18, 2016 at 11:30 am #

    So I had a 650b conversion suggested to me for a number of reasons but the main reason was the fact that i have ~ 1mm of clearance at my fork crown with a 40c tire and 2mm at my chainstays. If I converted I can run a 650x44c tire and still get better mud clearance.

    My issue is that I plan on upgrading my frameset in the future (which I why I choose not to get a better fork) so there is the possibility that the frame I get will either have better 700c clearances, or that it won’t fit the 650b wheels that I would want to get.

    • Guitar Ted July 18, 2016 at 6:23 pm #

      Kris- Wow, you are asking me to make a call on a bike I cannot see. That is nigh unto impossible to do with any good outcome. So, I would ask kindly that you consult a bike shop, or a local frame builder if possible, where you can take the bike and get some good feedback based upon some real world observations of your specific bike.

      That said, since you are thinking of an upgrade, why not press that into go mode now instead of waiting? This entire quandary could maybe be avoided? Sounds like your best option from what I have here to work with.

      Thanks for reading!

      • Kris July 19, 2016 at 8:23 pm #

        Thanks for the reply. To be completely honest after an incident I had yesterday with my front tire rubbing against the crown of my fork for no explicable reason, I’m more inclined to upgrade sooner rather than later.

        What I will say is after running my 32c tires again I feel like converting to a 650b would make sense for me if I can achieve the nimble-ness that my narrower tires have but gain the volume and traction that I get with my 40c tires.

  7. Ryan August 6, 2016 at 3:53 pm #

    GT, how much room do you have with the WTBs on the Tamland? I’m trying to find something with discs and fits 48s (hopefully with fenders). Thanks.

    Ryan

    • Guitar Ted August 6, 2016 at 5:57 pm #

      Lots of room, Ryan. I didn’t try fenders, but I think that they would fit on a Tamland with these wheels.

      • Ryan August 6, 2016 at 11:57 pm #

        Fabulous, this frame looks like a good candidate for my “Jones lite” project (discs, Jones bars, 650Bx48s, fenders, slackish angles).

        Ryan

      • Mike August 18, 2016 at 10:05 pm #

        What do you think is the biggest 650B tire that would fit in the Tamland (2014)? and the biggest 700c tire? (I’m wondering if I can fit in something like the Continental Race King RaceSport 29×2.0 tires, which measure out to 48mm, or if I should go to 650 and try to squeeze in a 27.5 x 2.20 Thunder Burt).

        …and a more general question, what do you think is a safe minimum clearance at the seat stays? 5mm? This is a Bay Area bike that will not very often see muddy conditions, but lots of packed and loose over hard. Thanks!

  8. Guitar Ted August 7, 2016 at 10:44 am #

    Ryan- Ironically it was a Tamland that I saw at this past Dirty Kanza 200 that had the 650B wheel set up and swept back touring bars that I was reminded of when I read your comment. Good luck with the project and I hope you have many miles of smiles on board that rig.

  9. Guitar Ted August 19, 2016 at 6:38 am #

    @Mike: I have put WTB Nineline 2.0 29″er tires in my Tamland and the wheels would spin freely, but only just so. Maybe less than a half a millimeter of clearance! So, obviously I never rode that set up. Right now I have WTB’s Riddler 45mm tires on that bike and I am not comfortable running anything wider than that in there. For 650B? I would think a lot of this depends upon the rim that you use and specifically the inner rim width. My Ailerons aren’t all the wide internally, and on those I would probably get away with a 650B X 50mm smooth tire, but that is about all, I think.

    Keep in mind that frame clearances are also for other debris besides mud. I have more problems with small pebbles and rocks getting stuck in between tires and parts of the frame when clearances are tight than I do mud, (because I avoid that in those instances), so it isn’t just for mud.

  10. Léo wattebled October 28, 2016 at 3:43 pm #

    Great article. Now we are searching how to find thise wheels in France to do some gravelbike adventure. http://pasquedescollants.com

  11. Ron October 30, 2016 at 5:37 pm #

    Thanks for great article. Instead of 3/4″ smaller diameter for 650b vs 700c, it is more like 1.18 inches, if you measured with a non-metric tape. You may have made a typo in your conversion from inches to cm. That is better news for those like me who are looking at 650b to increase standover height.

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