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Cyclocross and Gravelbiking (Recreational) This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like : "Unbound Gravel". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

650B for gravel is....out?

Old 08-03-22, 09:00 AM
  #26  
walnutz
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This thread has me wondering: what are the effective differences between, say, 650bx47 and 700x47 on the same frame, besides a higher BB?

Curious because I used to have a bike built for 650b that made me fall in love with the rim size. It was sadly stolen and now I have a bike that could accommodate both tire sizes listed above.
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Old 08-03-22, 09:10 AM
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650b wheel-sets are now considered so anti-trendy that they are hazardous waste and are a liability.

As a favor to everyone, I am prepared to dispose of your wheel-set free of charge. All I ask is that you pack them very carefully and pay for shipping directly to me.
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Old 08-03-22, 09:14 AM
  #28  
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Originally Posted by walnutz View Post
This thread has me wondering: what are the effective differences between, say, 650bx47 and 700x47 on the same frame, besides a higher BB?

Curious because I used to have a bike built for 650b that made me fall in love with the rim size. It was sadly stolen and now I have a bike that could accommodate both tire sizes listed above.
The problem with 700 x 47mm is that the tire/wheel combo has too large a diameter compared to something like 700 x 28mm, and will change the handling properties of the bike (it will become less responsive and a bit more of a sluggish feel to ride, especially climbing), more toe overlap, etc. The great thing about 650b x 47 is the outer diameter is approximately what 700C x 28mm would be, so the bike handles in the way that it would with 700C x 28mm tires, preserves the geometry, better toe overlap clearance, etc.

If you are really tall, you might prefer the large wheel/tire combination.
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Old 08-03-22, 09:19 AM
  #29  
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Originally Posted by walnutz View Post
This thread has me wondering: what are the effective differences between, say, 650bx47 and 700x47 on the same frame, besides a higher BB?

Curious because I used to have a bike built for 650b that made me fall in love with the rim size. It was sadly stolen and now I have a bike that could accommodate both tire sizes listed above.
The arguments here are going to be pretty much identical to the long running debate in MTB over 27.5" vs 29".
https://www.theproscloset.com/blogs/...waAt_oEALw_wcB

27.5” MTB wheels

  • Quicker and more playful handling
  • The traditional choice for downhill riding
  • Smaller wheels are generally lighter, stiffer, and stronger
  • Good option for shorter riders
Who’s it for: Riders who prefer playfulness, maneuverability, and style versus outright speed. Riders who specialize in jumps, freeride terrain, or bike parks.

29” MTB wheels
  • Rolls over rough terrain and obstacles more easily
  • The traditional choice for cross-country racing
  • Becoming popular for trail, enduro, and even downhill racing
  • Good option for taller riders
  • Who it’s for: Riders who want to maximize uphill and downhill speed for racing or crushing Strava segments. Riders who want to stay up-to-date with the latest tech.
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Old 08-05-22, 12:18 PM
  #30  
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Originally Posted by walnutz View Post
This thread has me wondering: what are the effective differences between, say, 650bx47 and 700x47 on the same frame, besides a higher BB?

Curious because I used to have a bike built for 650b that made me fall in love with the rim size. It was sadly stolen and now I have a bike that could accommodate both tire sizes listed above.
I was thinking about this today more. I run 700x28 road tires on my CX bike, which can also officially handle up to 700x45mm, but I'm guessing 47mm is no problem. I've never used anything wider than 38mm on that bike, but there is a noticeable difference in handling when I swap between 700x38 gravel tires and 700x28 road tires. 700x47 would feel huge.

The bike is much quicker and responsive in turns on the road rubber. I attribute most of this to the tread and width, rather than change in diameter - but that probably plays a bigger role than I realize.

My frame geometry doesn't work with 650b - the chain stays are hourglass so I'm guessing there's less clearance in 650b size than with 700c, but it would be interesting to try a 650b sized wheel on there with wide gravel tires to see if it retains some of that same feeling as the 700x28 road setup.
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Old 08-05-22, 04:10 PM
  #31  
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Originally Posted by msu2001la View Post
I was thinking about this today more. I run 700x28 road tires on my CX bike, which can also officially handle up to 700x45mm, but I'm guessing 47mm is no problem. I've never used anything wider than 38mm on that bike, but there is a noticeable difference in handling when I swap between 700x38 gravel tires and 700x28 road tires. 700x47 would feel huge.

The bike is much quicker and responsive in turns on the road rubber. I attribute most of this to the tread and width, rather than change in diameter - but that probably plays a bigger role than I realize.

My frame geometry doesn't work with 650b - the chain stays are hourglass so I'm guessing there's less clearance in 650b size than with 700c, but it would be interesting to try a 650b sized wheel on there with wide gravel tires to see if it retains some of that same feeling as the 700x28 road setup.
Me too. I can get up to 54mm in the front.

on 28 or 32mm tires, it handles pretty much like it is designed (OEM is 33mm).

If I put 50mm front, 40mm rear (maxed out both), it gives the bike more trail, handles more stable, and is better for hard core gravel and even single track. Maybe 10mm more trail, its not huge, but it makes a difference.

Oh yeah, toe overlap. That is a thing if I go big on the front.

Bigger difference is tire design A furious fred handles like a road tire with a nice rounded cross section. A Thunder Burt has squared off shoulders and significant knobs; it handles a LOT different in the turns.

Tread width can be the same - if I max out the pressure on a 40mm tire, the tread on the road isn't a whole lot different than a 28mm tire. I've done that, but it is horrible in that it defeats the purpose of having wider tires and makes the bike feel way too stiff for the type of riding I want to do on those tires.
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Old 08-07-22, 09:52 AM
  #32  
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Originally Posted by msu2001la View Post
This. The main benefit of 650b for most people was the ability to fit wider tires than they could with 700c. This is no longer a problem with most "modern" gravel bikes.
You could include more and more "road" bikes, too. I dunno how many other people I speak for, but if I'd been able to fit 32mm tires and possibly fenders into the road bikes I had a decade ago, I doubt I would have pursued 650B at all.
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Old 08-07-22, 12:55 PM
  #33  
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Originally Posted by chas58 View Post
I think you are right. Falling out of favor is basically how the bike industry works. I think it may apply here, like it or not. Just look at 650b on the mountain bike side of things. They found that 700c is marginally faster, and gave up on 650b.
In cross-country this is true, but 27.5” is still the preferred size for gravity riding as far as I know. There’s a vogue for a 29” front and 27.5” back wheel in World Cup downhill racing at the moment, but no sign that 650b is going away.
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