650B Vs. 700C: The Geek Edition | GCN Tech Does Science

650B Vs. 700C: The Geek Edition | GCN Tech Does Science

Over on GCN we were lucky enough to test some brand new 650b wheels with big volume offroad tyres. We were able to go into a bit of detail about the difference between 650b and 700c wheels over there, but felt like the tech obsessed cyclists could use a more in depth discussion.

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GCN 650b vs 700c

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Readers Comments (50)

  1. Don’t mean to be a total douche, but why is that all of the sudden Gravel bikes need to have 40mm tires to go over gravel, when CycloCross bikes go over mid, sand, gravel and dirt on a 33mm tire? are we overcompensating?

  2. Way to much tech just ride your bikes

  3. Rubbish, why put different wheels in bikes not made for them?

  4. Christian Iribarren March 30, 2021 @ 11:07 pm

    I drank the kool aid & switched to 650b and love it. Its not about the wheel size, it’s running 40psi & cornering @ higher speeds that i love

  5. i guess i will measure out my trekking bike if it would fit much wider tires with 650b instead of 700c wheels to make a really comfy cruiser out of it. but i guess there is not that much more room laterally on the fork anyway

  6. The bike’s riiiight about to fall over at 9:35

  7. Thank YOU JESUS March 30, 2021 @ 11:12 pm

    I like this!!! Thanks! Very helpful

  8. Matthew Salvadore March 30, 2021 @ 11:14 pm

    Hey I would love it if you guys did an ”is steel really real” video.
    I mean everybody says it but what’s the benefits/drawbacks ?
    Cmon gimme some science not just a slogan!!

  9. I have a 700c rim with 29 saguaro 2.2 on it

  10. Logic: Buy 650b wheels because of rough roads. Then make them out of carbon fiber, the least flexible of all materials to make wheels out of.

  11. Can i use 622×47 or 28×1.75 tube to a 584×42 or 27.5×2.10wheel?

  12. Elizabeth's Healing Path March 30, 2021 @ 11:20 pm

    My 10 year old bike is equipped with 650c and it has been harder and harder to find. and now this year I can only find continental gaterskin. which i hate. so now i keep seeing 650b everywhere. I am giving my bike a facelift these year. Wanted to buy new wheels. Hope i can just ass 650b stuff to my bike so he can keep on rolling!

  13. At this moment i’m building a gravel bike. I wanne put 650b wheels in the machine. But strugling with the axle. Wich wheels fit a 12mm front axle?

  14. someones a wee bit hungover

  15. If it’s harder to turn the handlebars then why not just lean into the turn instead of relying on the handlebars turning (like racing bikes)

  16. I’ve had a 700c on a 29er wheel set worked just fine. 700c come in tire types that 29er dont try getting a road slick in 29er 700c are all over the place cheap

  17. i’m interested to see zipp’s study on the aerodynamic gains of a 650b wheel. and also, what’s that background music from 5:35 on?

  18. I need some clarification on something! I’ve read posts where people claim that a 23mm 700c tire is equivalent to a 38mm 650b tire. This confuses me! I understand that 23 and 38 are referring to the width of the tire and not the height. The total diameter, according to your video, of all 650 tires is 650mm and all 700c wheels would be 700mm. So the height will always have a 5mm difference? I must be missing something. Can someone help elaborate on this.

  19. Terrence De Leon March 30, 2021 @ 11:30 pm

    Does switching from 700c to 650b can lower the ground clearance?

  20. My frame can fit a 700×45 Riddler or a 700×44 Compass Snoqualmie Pass. It can also fit a 47mm or 48mm 650b. Now, what I am wondering is that if I could fit such a large 700c tire, would moving up to the 650b, be worth it? Pun intended. I understand the reason many move up to 650b is so that they can utilize larger volume tires in a frame that could not accommodate large volume with 700c. But if your frame can fit 44mm or 45mm 700c then would the small amount of extra volume in a 47-48mm 650b make a really noticeable difference? Perhaps some of the handling characteristics of the 650b is preferred as well over the 700c? What’s your opinion? If you had to choose only one? Thanks 🙂

  21. Andrey Maradudin March 30, 2021 @ 11:32 pm

    I prefer to put on wheels 622mm – tires 48 mm. Why should I choose from two bad options?

  22. To make things more complicated: a bigger wheel and tire with better brakes up front.

    The rear wheel is dragged over an obstacle (front is pushed over, which is much harder somehow) and is more easily controlled when you lose traction. The front wheel takes about 80% of the braking too.

    When converting from 26" mtb with rim brakes, it was common to upgrade the fork to a 27,5 or 29" disc brake with better shocks. Best of both worlds.
    Even today it is common to see 29" front and 27,5" rear on some mtb’s

    This will only carry over to gravel bikes with big clearances in the forks though. You could save some money going for a 650b rear wheel only. Keeping the front 700c. It could also make the geometry more relaxed when running the 650b, a good thing on gnarly gravel.

  23. Tech Question: With 700c x 28mm tires on my road bike, I have approximately 3mm clearance on each side of the tire (inside the fork/chain stay/seat stay). The angle of the frame—inside the fork/chain stay/seat stay—increases as it nears the hub. A smaller wheel accommodates a wider tire because its shorter radius sets the tire at a wider point in the frame. The radius of the 700c—from hub to rim—is 311mm (1/2 of 622). The radius on a 650b is 292mm (1/2 of 584). Measuring 292mm up from the hub, I find there is approximately 41mm width inside the fork—where the edge of a 650b wheel would sit. Without knowing the height of a given tire, what’s the largest tire my frame can accommodate using a 650b?

  24. Too bad UCI sets a minimum diameter of 55cm for wheel+tyre! Otherwise we would be racing with Moulton bikes.
    I’d love to build a TT bike just on that minimum wheel size limit, there are several smaller rim "standards" but then you can’t find nice racing tires. I once had an hybrid with 559 wheels (26er) with 25mm Maxxis Detonator tires, but I can’t find those anymore and the bike was sold. At least I’d like a 650C TT bike…

  25. Worldwide Ghosts March 30, 2021 @ 11:41 pm

    I’ve got 600x23c tyres and they seem great. They are fast and light.

  26. Im planning of buying montra helicon x bicycle it has 27.5 × 1.75 (650b) tires can i change that to hybrid tires or road tires, waiting for your reply, can i use the same stock rims to convert to 700c

  27. I didn’t get "tired" of watching this. Thanks!

  28. Timofei Gerasimov March 30, 2021 @ 11:44 pm

    This is very confusing

  29. Mattias Andersson March 30, 2021 @ 11:45 pm

    Tire or tyre 🤔

  30. Just bought my 650b boomtrack Hook Ext yesterday… All i can say is it felt awesome. and i have the benefit of 2 bikes in one

  31. Thank you! Nice Video!

  32. Poltergeist Ducs March 30, 2021 @ 11:50 pm

    can my aero frame disc fit a 650b?

  33. Ím so confused now

  34. Franco Della Mura March 30, 2021 @ 11:53 pm

    Simon, who was that amateur that almost took you out??!!! Great pointers and a lot of information that i didn’t know! Starman!

  35. Brilliant recovery and response on that "almost stack" (whatever that means)

  36. Im coming from germany, so are the 700c what we hall 28" and 650b 27,5"?

  37. How do you fit the 700c on 650b rims? I have mtb and I bought 700×35 for my 650b rims, but the tires look way too big. Any tips?

  38. Hail the Geek !! More like this please 🙂

  39. How are they on the road???

  40. Angle impact of a larger wheel on a 5cm object would less, not more i would have thought.

    I remember when GT added a 700D rims to their early 90’s hybrid mtb’s.
    They also i remember, rolled pretty well even combined with a now heavy cro-mo steel frame.

  41. Did Si retire from GCN ? And matt ? I don’t see them in the new vids 😕…

  42. More on riding 650Bs over on GCN here http://gcn.eu/650bVs700c

  43. Great job on this wheel tech discussion you guys. Very informative. And done with you classic witty humor! Thanks!

  44. Can you use a 650c tire on 650b wheel?

  45. What about Tarmac sl6.
    Can 650b wheels fit on them.

  46. Goat Rides Bikes March 31, 2021 @ 12:00 am

    Most riders tires are severely over inflated, so there’s that as well.

  47. I loved all the detail and explanations in your video.

  48. Earvin and aly Adventures March 31, 2021 @ 12:02 am

    Question. Can i change my 700c wheels into 650c or 650b. Is there any available wheelset using caliper breaks?

  49. So this is a strange question, and I realize there are geometry considerations, but assuming all else is equal: If there is a 7% aerodynamic advantage AND a weight advantage, couldn’t you put the same width tires on your 650b rim as you have on your 700c rim and be faster on the road, period? (obviously then you wouldn’t have the clearance for your offroad tires but I’m talking about on-road theoretical performance here… if narrow 650b tires and bikes were actually made)

  50. The only glaring problem is that the new 650/29er frame geometry doesn’t work well with 26" rims. Ha ha.

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