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650b or 700c when clearance is not an issue

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650b or 700c when clearance is not an issue

Old 06-24-19, 11:39 AM
  #1  
Ian401
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650b or 700c when clearance is not an issue

Hello! I am brand new - literally created an account to ask this question because I couldn't find the specific question I have.

I just built a Soma Wolverine and would like to get into touring (both pavement and gravel). I also just got a King hub that I will be building into a new wheel for that bike (since I had to tear the wheels off my El Mariachi and the rims are quite wide so either way I can't continue to run them... sad).

So my question is... for touring, double track trails, gravel grinding, and pavement pounding (punching, pushing, peddling??? lol) should I build a 650b or 700c wheel?

I know most 650b conversion threads talk about having more clearance and a supple-er ride (due to fatter tires) but those people are usually using bikes that can only clear 700 x 40 tires and 650b gives them more rubber.... but my bike clears 29 x 2.1 Nanos no problem and that won't change much if I swap to 650b. If I do choose 650b I would use WTB Byways for commuting and road/gravel stuff and Ikons when I am trying to get more ~rad~

So if I build a 650b wheel and the clearance doesn't really change, is there really any benefit? Or will I just be stuck with a wheel that is slower (rotational speed), doesn't roll over things quite as well, and in the middle of nowhere with a blown tire in a weird size that the LBS doesn't have?

The only benefit I see right now is that (according to Soma) a 650b x 2.0 tire fits with fenders - as opposed to only 45c tires in the 700c form. Has anyone done this to their Wolverine or a similar bike with minimal clearance changes? Did you like it? Or are the 650b tires a fad just like those Livestrong rubber bracelets that were ever so popular in middle school?
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Old 06-24-19, 12:59 PM
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If you are doing mixed riding on dirt/road, there are a lot more tyre options in 650B. But if your riding is mostly dirt I would stick with 29x2.1 and use a separate wheelset for road.
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Old 06-24-19, 01:09 PM
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Old 06-24-19, 01:10 PM
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Originally Posted by Elvo View Post
If you are doing mixed riding on dirt/road, there are a lot more tyre options in 650B. But if your riding is mostly dirt I would stick with 29x2.1 and use a separate wheelset for road.
Also, what this guy said.
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Old 06-24-19, 01:45 PM
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I would probably use a 40-45mm tire for all that you listed, so my choice would be a 700C wheel every time.

a 40-45mm tire is plenty comfortable for me on all the gravel that Ive rolled over, any double track Ive ridden, and is more than enough for comfortable touring. I dont recognize 'pavement punching' as a thing, but just pick a fast tire in whatever size you get and riding on pavement will be fine.

There is no benefit to me for 650b/27.5(my MTB has em) on roads or gravel and wheels happen to be one area where I have no interest in experimenting with different options just for the experience of it.
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Old 06-24-19, 02:20 PM
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All other things being equal (including tire width), the 650b will lower your bottom bracket significantly. The biggest issue there is probably pedal strike, although theoretically the bike will be more stable when it is lower. If you run a small frame, toe strike may be an issue with large 700c tires (and more so if you plan on running front fenders).

like mstateglfr said, most people run 30-45mm tires in 700c, and 47mm up in 650b.


My advice - stick to the tire diameter that is as close to what your bike was designed for (what it comes with stock). This is going to give it the best handling dynamics and optimum height.
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Old 06-24-19, 02:24 PM
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Read this: http://ridinggravel.com/components/w...-650b-vs-700c/
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Old 06-24-19, 03:50 PM
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If you've got the clearance and aren't shorter than 5'6" or so, 700c is a superior wheel size for all but the most mild gravel. The rollover advantage is just too large to ignore and that brings additional comfort, speed and momentum.

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Old 06-24-19, 04:19 PM
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Originally Posted by chas58 View Post
All other things being equal (including tire width), the 650b will lower your bottom bracket significantly. The biggest issue there is probably pedal strike, although theoretically the bike will be more stable when it is lower. If you run a small frame, toe strike may be an issue with large 700c tires (and more so if you plan on running front fenders).

like mstateglfr said, most people run 30-45mm tires in 700c, and 47mm up in 650b.


My advice - stick to the tire diameter that is as close to what your bike was designed for (what it comes with stock). This is going to give it the best handling dynamics and optimum height.
If you spend any amount of time on pavement this is a big deal. 700x40 feels way different than 700x23/25 if any of you swap to skinnies regularly. 650x40 puts you at a similar diameter if you're riding a more roadish gravel bike and mellower terrain. A local runs 650x38c on his OPEN UP at our local crits and is still fast and can ride it home afterwards down the rail trail. He says he hates the way it feels with 700c wide slicks
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Old 06-24-19, 06:45 PM
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If you have clearance for a 29 x 2.1 tire on 700c, I would go 700c. To me the advantage of 650b for gravel or rough roads is when you need tire clearance. There is a reason the 29er is coming on strong in downhill mountain biking, as it roles over crud easier. The smaller 650b may have a slight acceleration advantage as the weight of the wheel is closer to the axle, but it also will not carry momentum through rough and loose gravel as well as the 700c for the same reason

My other reason is I am 6'4" and a big wheel in my big frames make me feel like I am riding a bit more in the bike rather that perched up on it. That's probably just me though.

I do find it hard to judge this issue by what I see other riders using, for if they are faster than me it is more likely it is the rider and not the bike.
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Old 06-25-19, 05:14 AM
  #11  
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In addition to the points mentioned above…

650b will be better climbing hills since wheel circumference is a variable in gear inches. Conversely the smaller gear inches may make you spin out at higher speed (depends on your gearing). If you're in an area that's hilly, 650b has a distinct advantage. If you like to go as fast as possible on the flats and downhill, then 700C has a distinct advantage.
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Old 06-25-19, 06:23 AM
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Originally Posted by JayNYC View Post
In addition to the points mentioned above…
While there's definitely a confluence between power, gearing and heart rate - 650b-700c changes in the range most people are doing aren't going to make a whit of difference. You can't just pull wattage out of a hat and "go faster".

The difference between 650b/700c is so fine that it makes zero difference to overall speed. Certainly no distinct advantage. Using the same size tires, the gearing difference percent change is a slightly more than 5% - the same as a cadence change from 90->95. If you adjust tire size appropriately - say going from 700cx23 to 650bx42 or 700cx28 to 650bx47 the difference is even smaller. I changed my gearing to test this last year and I wasn't able to find any difference either in time measured or performance in the training crit I do. Going from 700cx35/40 tires using 46/11 to 650bx42/47 on 48/11 or 50/11 there was no performance difference.

Think of it this way - the cadence change to accommodate the speed difference (for same size tires on 700c/650b) is only 5 rpm (5.5% change) but the power requirement is 17-20% (depending on the calculator you use). I'd wager that everyone can pluck 5 rpm from the end of their limit if they had to, but no one can push an additional 17% power.

I've found 650b worse at climbing short hills and very steep hills as there's less momentum and inertia - especially once you get down to <60 rpm. It's much harder to go over the top of the pedal stroke on 650b. So far it seems to be a wash for longer hills and more mild hills but 700c certainly feels better.
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Old 06-25-19, 06:39 AM
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Originally Posted by Spoonrobot View Post
While there's definitely a confluence between power, gearing and heart rate - 650b-700c changes in the range most people are doing aren't going to make a whit of difference. You can't just pull wattage out of a hat and "go faster".

The difference between 650b/700c is so fine that it makes zero difference to overall speed. Certainly no distinct advantage. Using the same size tires, the gearing difference percent change is a slightly more than 5% - the same as a cadence change from 90->95. If you adjust tire size appropriately - say going from 700cx23 to 650bx42 or 700cx28 to 650bx47 the difference is even smaller. I changed my gearing to test this last year and I wasn't able to find any difference either in time measured or performance in the training crit I do. Going from 700cx35/40 tires using 46/11 to 650bx42/47 on 48/11 or 50/11 there was no performance difference.

Think of it this way - the cadence change to accommodate the speed difference (for same size tires on 700c/650b) is only 5 rpm (5.5% change) but the power requirement is 17-20% (depending on the calculator you use). I'd wager that everyone can pluck 5 rpm from the end of their limit if they had to, but no one can push an additional 17% power.

I've found 650b worse at climbing short hills and very steep hills as there's less momentum and inertia - especially once you get down to <60 rpm. It's much harder to go over the top of the pedal stroke on 650b. So far it seems to be a wash for longer hills and more mild hills but 700c certainly feels better.
I'm talking points of failure. When you fail to get up a hill (or you're miserable doing it) because your bike is geared too high, or you start spinning out because your bike is geared too low. At those points the 5.6% can be the difference.

Around here (the NYC metro area) the gravel roads often involve steep hills. It's pretty typical to do 4,000 feet of climbing over a 40 mile ride. There's one ride I do where I climb over >1,000 feet in the first 6 miles. If I have it in me, I just don't go to the lowest gear and I can climb the hill like you describe. But when I don't have it in me, I need the lower gearing. So, for me, 650b is the clear winner. But yeah, if you've never wished for lower gearing, then the smaller circumference of 650b isn't a plus.
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Old 06-25-19, 06:54 AM
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The situations you are proposing do not happen in the real world when making the wheel size and tire changes being discussed.
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Old 06-25-19, 08:06 AM
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Two sets of wheels for mine. 700x40 knobby and 700x30 slick.

It's a barely perceptible change in gearing.

I don't have a power meter.

My road bike, at 700x25 with a 34/30 granny gear feels about the same up a steep hill as my gravel with a 40/42 granny. Don't forget the rowdy bike is 4lbs heavier.

I have two rides near by. Gravel that climbs 3100' in the first 13 miles. And a road ride that happens to be exactly the same amount of climbing. Both hurt. In terms of effort, the gravel is harder and much slower. Just thought I'd throw that in for the the guy who thought 1000' in 6 is a big climb.

In the days of 8-9 speed, everyone had multiple cassettes. Sometimes you want to spin, sometimes it's steep. With 10/11/12+ this is less necessary. If you are riding around with a cassette that isn't optimized for your legs/terrain/ and wheels. Do it right away. It's literally the first thing to do to ensure you're riding as well as possible.

Road, 12-25 flat days, 13/29 low end for trailer, 12-30 for mountains.

Gravel 12-36 rolling terrain without much steep. 11-42, getting rowdy.
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Old 06-25-19, 09:30 AM
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Originally Posted by Spoonrobot View Post
The situations you are proposing do not happen in the real world when making the wheel size and tire changes being discussed.
That's odd. It happens to me and folks I ride with pretty much every time we ride steep gravel roads (and all the gravel routes here have steep sections). When you're struggling up a steep hill, you want the extra 5.6% of help. I can't ever think of one of those times when I'd say "I want this to be more difficult".

Here's a real world gravel climb where most ordinary people would appreciate the extra 5.6% of favorable gearing that 650b wheels would give them…

https://www.strava.com/segments/13016043
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Old 06-25-19, 09:35 AM
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Originally Posted by rosefarts View Post
I have two rides near by. Gravel that climbs 3100' in the first 13 miles. And a road ride that happens to be exactly the same amount of climbing. Both hurt. In terms of effort, the gravel is harder and much slower. Just thought I'd throw that in for the the guy who thought 1000' in 6 is a big climb.
That gravel climb sounds familiar. Do you live in NW Georgia? If you do, what's the road climb? I'd be interested to check it out.
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Old 06-25-19, 09:39 AM
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Yeah it's too bad no one can climb hills with 700c.
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Old 06-25-19, 09:55 AM
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That's odd. It happens to me and folks I ride with pretty much every time we ride steep gravel roads (and all the gravel routes here have steep sections). When you're struggling up a steep hill, you want the extra 5.6% of help. I can't ever think of one of those times when I'd say "I want this to be more difficult".
Why not just use the appropriately sized chain ring to give you the gearing you need?
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Old 06-25-19, 10:01 AM
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Can't do that on those world famous NYC gravel climbs.
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Old 06-25-19, 10:11 AM
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Originally Posted by ksryder View Post
Can't do that on those world famous NYC gravel climbs.
Never said it was world famous. But it's real world. And the examples of bigger climbs just prove my point that what I'm talking about is actually rather average.

There's no need for some of you to be haters on this issue. It definitely doesn't contribute positively to the conversation. I'm an average 51 year old guy riding in what are real world conditions around here. I chose a bike with the smallest chainring and biggest cassette cog I could find (without sacrificing too much on speed when I'm riding on pavement), and yes, the extra 5.6% of gearing that I get with 650b helps me. It's wonderful you don't need or want it, but saying only your experience is "real world" is flawed (to put it really nicely).
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Old 06-25-19, 11:17 AM
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NYC gravel is probably like California gravel. It's just different, you wouldn't understand.

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Old 06-25-19, 12:05 PM
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Originally Posted by Spoonrobot View Post
That gravel climb sounds familiar. Do you live in NW Georgia? If you do, what's the road climb? I'd be interested to check it out.
Southern Colorado.

The day after I got my road bike 3 years ago, I rode it up Pike's Peak. Stock it came equipped with a 53/39 crank and a 12-25 cassette. It was most certainly a leg day.
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Old 06-25-19, 01:16 PM
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Originally Posted by Spoonrobot View Post
If you've got the clearance and aren't shorter than 5'6" or so, 700c is a superior wheel size for all but the most mild gravel. The rollover advantage is just too large to ignore and that brings additional comfort, speed and momentum.

That what we now call 700C wheels were originally called "28-inch" just goes to show you they had this all figured out 100+ years ago.
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