Toggling between 650b and 700c wheelsets.

[XXtwindad]

This is an addendum to the thread I posted yesterday. It's a slightly different take. Gravel bikes have opened up so many possibilities. I'm curious if any of you have run both 650b tires and 700c tires and what you feel the differences are?

I have a bike that can fit 45c tires. Presumably, that means that I can run wider 650b tires, perhaps as large as 27.5 x 2.2. (I'm double checking with the frame builder). Assuming the terrain is almost exclusively dirt, wouldn't the wider 650b tires be the better choice? Interesting article here: https://glorycycles.com/ride-notes/700c-or-650b-the-wheel-truth/

The WTB Sendero at 650X47c is highly regarded for dirt applications.
Additionally, the new ENVE gravel fork will fit a maximum of 700x50 or 27.5X2.2 tires, so clearance isn't really an issue.

I know several of you own the O.P.E.N. UP (and UPPER) and switch back and forth between wheelsets. Any thoughts would be greatly appreciated.

[Jaybee]

I do this. Mavic XA wheelsets for both, so same hubs = same brake rotor location and same cassette location = no adjustments necessary.

For 27.5, i'm currently on a Bontrager XR1 2.2 in the front and XR0 2.0 in the back, which is the most I can fit (and even that's a pretty sketchy definition of fit). My next bike will absolutely have room for 2.2 front and back.

More volume is definitely nice on chattery, chundery stuff, but IME, you also lose some rollover relative to 700x45. All in all, I think I prefer the 27.5 for singletrack.

The Sendero looks interesting for dirt, but probably a bit knobby for all the paved I ride between trails, so I haven't tried it.

[SlowPokePete]

Well, I haven't switched back, but I've got 5,000 miles on really nice I9 Carbon 700's, then another 10,000 miles on current 650b (WI rear hub, SON dynamo front, HED Belgium Plus)...

If you want bigger rubber, whether it be for gnarlier type riding, or to explore the supple world, 650b is the way to go.

I know my I9's (hanging in the basement) were lighter and faster, but I'd say you don't want to go over a 38mm wide tire.

I've been on RH Switch Back Hill Extralights (650x48) for about 300 miles, and the ride is smoooooth...

I like that, and don't wanna give up the dynamo, which is what keeps me from throwing those bigger wheels on again...

SPP

[Spdntrxi]

I go back and forth.. pretty much leave Compass file tread type tire on the 700c wheelset and I have 2 650B wheel sets .. previous one had smooth type tire and the other had gravel rated... they both have more tread now. The 700c is currently 35mm and the 650b are 42mm and 47mm.(42's are for mud clearance)

I am a lot more comfortable in the chunk with 650b and general descending as well. Trails are pretty hardback with dust.

[yinzerniner]

I have a bike that can fit 45c tires. Presumably, that means that I can run wider 650b tires, perhaps as large as 27.5 x 2.2. (I'm double checking with the frame builder). Assuming the terrain is almost exclusively dirt, wouldn't the wider 650b tires be the better choice?

Yes. You answered your own question. Tire should always match the terrain.

And I had the sendero mounted on a previous UP and it’s a nice tire but did not work with most of my riding. The knobs are really pronounced and on tarmac quite mismatched. If you’re only going on loose and muddy conditions then it’s perfect.

[XXtwindad]

The reason I'm asking about this is I stumbled across this feed on Instagram (while searching for another bike):

https://www.slugbicycles.com/our-work/kevins-gravel-bike

It's got 27.5 X 2.4 tires and he's riding it all around the Marin Headlands. Looks like an awesome steed for that purpose. Then I notice the specs. It can fit 700 and 45c tires or the 27.5 x 2.4 tires. And has 425cm chain stays. My bike can fit 45c tires and has 435 chain stays. So why can't I run 27.5 X 2.2 tires? I'm thinking I can! Could be a game changer! (The ENVE gravel fork tops out at 27.5 X 2.2)

[Spdntrxi]

^ depends on the shape of the chain stays most likely..I can fit 50mm in the fork but only run 47 (maybe 48) in the rear. if they grow to 50ish mm I will rub.

hence sometimes I'm thinking of making the Ti Gravel leap myself with a new Frame

[sleepyfelix]

650b undoubtedly better in the loose stuff, but if you also do a lot on tarmac still, I think you (ideally) need to run very light carbon rims if going 650b to make up for the extra weight of the tyres. I found that otherwise 650b can feel a bit sluggish (assuming you are more used to 700c- which it sounds like you are?)

[XXtwindad]

^ depends on the shape of the chain stays most likely..I can fit 50mm in the fork but only run 47 (maybe 48) in the rear. if they grow to 50ish mm I will rub.

hence sometimes I'm thinking of making the Ti Gravel leap myself with a new Frame

Here you go :)

[XXtwindad]

650b undoubtedly better in the loose stuff, but if you also do a lot on tarmac still, I think you (ideally) need to run very light carbon rims if going 650b to make up for the extra weight of the tyres. I found that otherwise 650b can feel a bit sluggish (assuming you are more used to 700c- which it sounds like you are?)

Yes, I am.

[EB]

Contrarian take 1: Kevin should get a mountain bike.

Contrarian take 2: Wheel swapping is a nice idea in theory, but in practice, it does change the geometry of the bike. A frame designer can optimize for one wheel size or the other, but accommodating both leads to a handling compromise with either size.

Personally I like 700c, but I'm 188 cm tall. I am really glad there's a market for 650b, but I think the advantage is being able to optimize the design and build of the bike for the height and fit of the rider, which are harder to swap than your wheels.

[d_douglas]

I had some Hope 27.5s with Senderos on my old Redline. It was fun and looked cool, but I preferred the 700c. I sold the smaller wheels (but still have the senderos if you need a set!)

These tires were very grippy where I live, but they were intended to be ridden offroad. On road, I agree that they’d feel sluggish.

[lavi]

Yup yup, and yup. That article does a good job.

I have both. For any real dirt/gravel/rough stuff...650b all the way.

My bike, while I don't go out of my way to avoid gravel, sees 99.8% tarmac. I ride the 650 when I want the nice plush, cush feel. I like it for nice, easy days when I'm not in any hurry. I like the feel of the float of the tires. I certainly can tell the handling/steering is tamped down though. When I want to go faster, with more precise/road bike handling/feel...it's the 700s. On the 700s, I ride 32s so I still get a nice plush factor over any 25 on wide rims. No comparison there. Horses for courses though.

No wrong answer. Just have to determine what type of riding you'll be doing, and what your personal preferences are.

[XXtwindad]

Contrarian take 1: Kevin should get a mountain bike.

Contrarian take 2: Wheel swapping is a nice idea in theory, but in practice, it does change the geometry of the bike. A frame designer can optimize for one wheel size or the other, but accommodating both leads to a handling compromise with either size.

Personally I like 700c, but I'm 188 cm tall. I am really glad there's a market for 650b, but I think the advantage is being able to optimize the design and build of the bike for the height and fit of the rider, which are harder to swap than your wheels.

Yes, that's a valid take. But I ride primarily non-technical fire roads. The Bay Area is full of them. Steep climbs with great views. I think they'd be much more fun on a gravel bike. At least the climbing part.

[d_douglas]

Yikes! Nice frame - another source of envy for me.

[XXtwindad]

Yikes! Nice frame - another source of envy for me.

Haha. It has my daughters initials on it. So, no epic races between the two of us :)

[yinzerniner]

The reason I'm asking about this is I stumbled across this feed on Instagram (while searching for another bike):

https://www.slugbicycles.com/our-work/kevins-gravel-bike

It's got 27.5 X 2.4 tires and he's riding it all around the Marin Headlands. Looks like an awesome steed for that purpose. Then I notice the specs. It can fit 700 and 45c tires or the 27.5 x 2.4 tires. And has 425cm chain stays. My bike can fit 45c tires and has 435 chain stays. So why can't I run 27.5 X 2.2 tires? I'm thinking I can! Could be a game changer! (The ENVE gravel fork tops out at 27.5 X 2.2)

Totally depends on the frame and fork design. Saying “this has the same numbers, so it must work like this other thing” doesn’t work without knowing the full picture.

A perfect example is the previous gen stigmata. It had plenty of clearance for 700x40c but 650b was limited to 40c or even smaller. Why is that? Because of the chainstay design, and that it was designed for 2x compatibility.

The slug bikes shown utilize chainstay plates instead of continuous tubing. Does your bike have that? Also they don’t list 2x compatibility, nor crankarm type or clearance, nor if it’s utilizing boost or super boost spacing. It’s pretty easy to get oodles of tire clearance when you push out the q factor and / or chainline, but then that introduces other variables which might not be favorable for your intended use / build.

Sorry, just saw you posted the alliance. Just judging from the pics you won’t get any larger than a 2.1 or so, as the chain stays are pretty wide and not fully dimpled at the tire rotation point. But you’re welcome to try otherwise.

[XXtwindad]

Totally depends on the frame and fork design. Saying “this has the same numbers, so it must work like this other thing” doesn’t work without knowing the full picture.

A perfect example is the previous gen stigmata. It had plenty of clearance for 700x40c but 650b was limited to 40c or even smaller. Why is that? Because of the chainstay design, and that it was designed for 2x compatibility.

The slug bikes shown utilize chainstay plates instead of continuous tubing. Does your bike have that? Also they don’t list 2x compatibility, nor crankarm type or clearance, nor if it’s utilizing boost or super boost spacing. It’s pretty easy to get oodles of tire clearance when you push out the q factor and / or chainline, but then that introduces other variables which might not be favorable for your intended use / build.

Yes. You're right. I'm not a geo expert. That's why I'm checking with the frame builder. It was designed around the GRX (31/48) crankset.

[sleepyfelix]

Yes, I am.

For ref. my experience was riding a steel gravel bike (Shand Stooshie). So 650b alu rims (Hunt) perhaps tipped it from acceptable weight to slightly too much.

[XXtwindad]

For ref. my experience was riding a steel gravel bike (Shand Stooshie). So 650b alu rims (Hunt) perhaps tipped it from acceptable weight to slightly too much.

OT: I love Scotland.

[robt57]

I have two that started out with 700 35-38, with occasional 40mm much more aggressive tread tires.

Both are sitting with 650b x 47 for a while now. One Teravail Cannonballs, the other WTB Bi-Ways. I might put 700x42s if I was going for a long long gravel ride, otherwise 650s for me. Add more than detract for my usual uses.

The bike with the very low BB has one sided road SPDs and 170mm cranks, the one with 14mm higher BB has 2x side SPDs, 175mm cranks.

FWIW, my Gary Paragon 29er has been a 27.5er for years.

[slowpoke]

Contrarian take 1: Kevin should get a mountain bike.

Contrarian take 2: Wheel swapping is a nice idea in theory, but in practice, it does change the geometry of the bike. A frame designer can optimize for one wheel size or the other, but accommodating both leads to a handling compromise with either size.

Agreed.

27.5 x 2.2" tires seem like one's riding a drop bar mountain bike. I know Mike Varley is a fan, but personally I'd rather be riding with flat bars on terrain that merits 2.2s.

[robt57]

I have run 2.1 MTN 650b on the Strong All Road. My Gravel Mongrel is a Pro CX Lynsky, it has worn 1.95 700s.

With these tires the Strong feels like a MTB bike, and the Mongrel feels like a 29er/truck. Considering I run my 29er as 650b for last 4 years, Not likely the Mongrel will see the 29er mode again. I have come to hate that truck feel personally...

I just take a MTN bike rather than do this, beyond trying it for curiosity.

[Cgeisler]

I run 36 Donnelly MSOs or 38 Specialized pathfinders x 700 (DT Swiss CRC 1400 -- spectacular wheelset) for training and racing during GVL season; and 47 WTB Horizon slicks or Maxxis Icon 2.1s x stans valor 650 hoops for fun/winter.

Running the WTB 47s x 650 is a brutal workout on long GVL training rides when the field is running 700s. Earlier in the year, on a long, tough shop ride, Collin Strickland giggled as he noticed them on my GVL bike (an Open U.P.)

But the 47s are bombproof and fun to screw around on, for sure. I run 30-35 psi in them.

[d_douglas]

Haha. It has my daughters initials on it. So, no epic races between the two of us :)

What are their initials ? I have two kids as well. My son would never know.

[Jaybee]

I know it's tough to do right now, but any way you can find a 27.5 wheelset for a test fit? Failing that, talk to Erik or check your build sheet. Or measure the space between chainstays about 330-350mm from the rear axle?

[John H.]

I have both and I ride primarily Mt Tam and west Marin trails.

I have a set of Enve G27 650b with Schwable Thunder Burt 2.1 tires, and a set of Industry9 ULCX TRA 700c wheels with Maxxis Ramble 700x40mm tires.
I run them both on my Open UPPER and also a custom Seven Evergreen.

I find the 650b to be fun and it has better traction- but I spend way more time on the 700c wheels because I find the 650b to be slower.
This becomes less noticeable as the terrain mix shifts to a higher % of offroad.

650b has slightly less toe clip overlap, I do find that I don't love the 650b as much on the Seven as it has a lower bb (75mm drop vs. 70mm bb drop)- The Seven feels like it tends to have more cranks strikes with the 650b.

[livesadventure]

One of the great paradoxes of gravel bikes that us non geometry literate folks won’t quite understand stand is that large 700c clearance doesn’t equal large 650b clearance, or vice versa.

That said, I ride 650b x 2.25 and trails and use 700c x 38 for road heavy or more mixed terrain rides. Both have i9 torch hubs and the same cassette, so the switch is seamless.

Are the huge tires overkill? Yes. Do they make the ride way more fun? Absolutely!

Once the bike is built you can test my wheel set on your frame if you’d like


Sent from my iPhone using Tapatalk

[XXtwindad]

One of the great paradoxes of gravel bikes that us non geometry literate folks won’t quite understand stand is that large 700c clearance doesn’t equal large 650b clearance, or vice versa.

That said, I ride 650b x 2.25 and trails and use 700c x 38 for road heavy or more mixed terrain rides. Both have i9 torch hubs and the same cassette, so the switch is seamless.

Are the huge tires overkill? Yes. Do they make the ride way more fun? Absolutely!

Once the bike is built you can test my wheel set on your frame if you’d like


Sent from my iPhone using Tapatalk

Thanks for the offer Luc. Much appreciated. There’s an old adage: “May you live in interesting times.” We definitely do. As it pertains to gravel bikes, it’s both an exciting time and a confusing one. As many people who live in the Bay Area know, the “gravel” here is pretty unique. A lot of endless (and steep) fire roads. The Marin Headlands and Mt. Tam are pretty much a cycling paradise. Houston has a great library of photos (mostly taken at dawn). Hard-core knobby enthusiasts would scoff, but I love those fire roads. The views are incomparable.

Having said that, the last time I tackled them (on a hard tail) it was pretty boring. You don’t need suspension. So what’s the solution? A rigid MTB? A gravel bike with fatter rubber? Tough call.

The guys at WTB are really high on the “Venture.” When I told them the “Sendero” and “Raddler” both looked great for dirt, the WTB rep was adamant. The “Venture” was THE tire for the Marin Headlands, and Bay Area dirt. Great review here:
https://www.ridinggravel.com/components/three-tires-from-wtb-venture-40mm-at-the-finish/

But if that’s the case, do I choose the 650X47 for comfort and rubber or 700X40 (there’s a 700X47 that’s a tad too big) for rotational speed? Which is the bigger sacrifice?

As I said, lots of choices in these interesting times. And much more fun than other topical events. :)

[joosttx]

Yes, that's a valid take. But I ride primarily non-technical fire roads. The Bay Area is full of them. Steep climbs with great views. I think they'd be much more fun on a gravel bike. At least the climbing part.

you are wrong. xc mtb is the way to go for "Bay Area"

[XXtwindad]

you are wrong. xc mtb is the way to go for "Bay Area"

Well, Im curious what part of the Headlands/Tam you need suspension for? Maybe Eldridge Grade and Hoo Koo for sure. But besides that?

[Spoker]

The advantages of 27.5 are even amplified with 29 x.
Get the bike for the job.
Chinese carbon is cheap.

[joosttx]

Well, Im curious what part of the Headlands/Tam you need suspension for? Maybe Eldridge Grade and Hoo Koo for sure. But besides that?

The list is long............

coastal view, Dias ridge, Hill 88, Miwok (most of it), Rock Bridge, Windy Ridge, Indian Springs, Harry Allen, Barbara Springs, Mt Archebald, Bills, Jewel, Mt Vision, ...... and the list goes on.

[XXtwindad]

The list is long............

coastal view, Dias ridge, Hill 88, Miwok (most of it), Rock Bridge, Windy Ridge, Indian Springs, Harry Allen, Barbara Springs, Mt Archebald, Bills, Jewel, Mt Vision, ...... and the list goes on.

I’ve done the Coastal, Dias, and the Miwok with a rigid. More fun, in my book. I’m not sure if “Hill 88” is the one people always try to set a Strava time going up just off the Bobcat. The rest I’m not familiar with so I’ll defer to your judgement.