DarKris

I'm probably shooting in the dark here but I've been looking around trying to find a frameset that has clearance for 650b tires around the 40-50mm size. I know that 3T and Open Cycles have frames that can run 700c/650b but to be completely honest it's way too expensive.

What I want to do is look for frames, mainly Cyclocross frames, that can take a 650bx42 tire at the very least. I also wanted to build a list of frames/bikes (mostly frames) that can handle this conversion.

Spoonrobot 

WTB's "road plus" is based around a 650bx47 tire so this list should work as a starting point for what you're looking for: Road Plus Compatible Frames | WTB

Although the vast majority of spec disc cross bikes will take a 650bx42 no problem. Usually the concern is bb drop and not tire width acceptance. You want to keep bb drop it on the lower end of 70mm.

tarwheel 

What size frame? All City just introduced a new disc brake version of the Space Horse frame and it's available for 650b wheels in smaller sizes. Tecnhically it's not a CX bike but that's academic.

Space Horse Disc | All-City Cycles

09box

If you look around on Craigslist sometimes, you might be able to find a Long Haul Trucker frame. They do pop up from time to time.

tarwheel 

Also check out the Soma Grand Randonneur, which is designed for 650b wheels. Their spec sheet says it will handle tires up to 38-42 mm wide.

Grand Randonneur Frame Set (v.2) | SOMA Fabrications

The Soma San Marcos also is designed for 650b wheels in sizes up to 57, but the maximum tire size in specs in 38 mm.

San Marcos Frame Set | SOMA Fabrications

DarKris

I ride a size 58. I'll be honest I like the fact that a lot of steel bikes have those wide tire clearances, however I really don't like the way they look. I know that may be counter productive, but that is half the reason why I'm looking at replacing my current frame.

tarwheel 

Does it have to be 650b? There are a lot of gravel bikes with 700c wheels that can handle wider tires -- eg, Raleigh Tamland, Black Mountain Monster Cross, Soma Saga, Wolverine and DC, etc.

mstateglfr 

VO Piolet Frameset - Frames
Velo Orange <---- geometry page

Can fit a fat ol 650. More 'adventure' of a frame for sure.

DarKris

The reason I'm looking for 650b is because I want the smaller overall diameter with the wider volume that it comes with. I was running 700x42c tires for the past few months and while I like the traction that it offered, the larger tires felt awkward to handle and hard to accelerate at stops.

The converse to that are the 700x32c tires that I had as backups which felt more nimble and responsive, but due to my weight their pressure was high and led to a very uncomfortable ride on uneven surfaces.

gomango

Have you tried a really nice tire like a Soma Vitesse SL in the 700x42 size?

Really a great ride and that's what I use on my Black Mountain Cycle Monstercross.

They roll up to speed quickly, I can run lower pressure and they corner well at speed.

FWIW I don't ride them in mud or sand, but they do perform well on hard pack gravel.

mongol777

Surly Straggler (650b or 700c), All City Space Horse (already mentioned - smaller sizes are designed around 650B)

DarKris

I have not, and to be honest I probably wouldn't unless I knew how much mileage I can get out of them. My main concern with more expensive tires is because of my weight I tend to wear through tires it seems, so I couldn't afford to keep replacing them if I wear them out fast (or god forbid cut them)

Again I liked the volume of my 42c's, I just felt like they got in the way too much if that makes sense.

BluesDawg

There are probably very many bikes around with 700c wheels that could work with 650B and 45-50ish wide tires. While it is not a new idea, people were converting bikes like this several years ago, it has only recently been revived with WTB's road plus tires and rims. Specialized has specifically designed the upcoming Sequoia to work with such tires and rims and will have a 650Bx47 version of the Sawtooth tire.

With few manufacturers on board at this time, we are at the stage where individuals experimenting are the main source of fit information. It's like where 27.5+/650B+ was with MTBs a year or two ago. There are threads on MTBR forums where people report frames and forks they have converted and how it worked out. They even came up with ways to measure clearance at the appropriate places to predict how well a frame would work. I am not aware of such a resource for road or CX frames.

DarKris

What I will say is that my main stumbling block has been trying to find bikes with good enough chainstay clearances as forks tend to have wide enough clearances for cross bikes, at least for the alloy/carbon frames that I've been looking at.

DarKris

Well, it seems that I may have found something that might be a godsend: Van Dessel Unveils A.D.D., Updates Steel WTF Do-it-All Bikes

And another one: https://www.carbonda.com/road/gravel/cfr505.html

Garfield Cat

The UP review, ok, expensive. But this review is one of the latest ones:

Six-Month Review: Open Unbeaten Path | Outside Online

DarKris

Thanks for that. As I can't afford that frameset my main takeaway from that is that going for a 650b compatible gravel bike isn't a complete waste of time. And since I have found a frameset that I'm interested in I am even more anxious about pursuing this "project".