Ok, I know there are probably a lot of similar posts, but I have a number of questions about 650b's that can hopefully be covered in one shot!

Firstly: how much larger than a 26" and smaller than a 700c are 650b's? And, how different are they in size to 650c's?

Nextly: I want to put some 650b's on a bridgestone mb3 mtb. I know this will work because of previous posts I've read where people have gotten 700's with fat tires to work in those frames... (I tried that and they do!). It sounds like using highly adjustable v or cantis will work with this set up, but I'm wondering if anyone has experience with this? Not specifically on the bridgestone, but just with 650b's on a standard MTB frame and how the brakes line up.

Lastly: what about putting 650b's on a cyclo cross frame? Will brakes with high adjust-ability work on smaller wheels in a bike built around 700c's?

I know you are wondering "Why?, why bother with all this?". Well, I'm small, I have short legs and a long torso. I like touring and running fat tires, and climbing with 700's is hard. Alternately I converted my MB3 into a touring setup with drop bars and slicks on the 26" wheels and the bike went from fitting to feeling TINY. I felt like an ant crawling across the ground. So... in my endless search for perfection with my bikes I'm thinking of trying 650's. Thanks for any feedback!

Here are the rim bead seat diameters (BSD): https://sheldonbrown.com/tire-sizing.html

Divide the BSDs by two to get the radius of each rim, then you can compare radii of various rims to see how far brake pads would have to be adjusted.

Remember, low = aero! Embrace your inner ant on the mb3 with slicks. As long as you don't
get pedal strike roll with 26. More tires to choose from.

The bike should stll fit the same. The crucial contact points have not changed their relationships to each other.

By this you mean the bike should still fit the same (brakes line up the same) with 650b's?

No. The bike will fit you the same way regardless of what wheels you put on it. Gearing can fairly easily be adapted to make the bike equally fast or hill-friendly whatever the wheels are.

The big change the OP made was replacing the MTB straight bars with drop bars. Unless he changed the stem, the reach is now much longer and that will change the feel and fit of the bike substantially.

Not sure what year MB3 you are referring to but a 93 with a 26" 2.3 Klein tire was right at the stay so I doubt a 650b would fit that year MB3

True. I'm not sure how a switch to drops without use of a much shorter stem can make the bike feel smaller.

I got the impression that smaller feel came from a switch to slicks.
The rim size change the OP's interested in can change BB height, standover and steering geo. It will do nothing for major fit realationships of BB-saddle-bars

I don't think perfection means taking a 650b wheels and putting them on a bike that takes a different size wheel. KHS and Jamis currently have 650b bikes and I suspect it may be cheaper at this point to buy a complete 650b bicycle than to build one. I did some research on this but I don't remember everything I saw.

I'm too lazy to check but I think the ISO for 26 inch, 650b and 700c wheels are 559, 584 and 622.

I think the frame geometry would need to be made for the 650b for it to be "ideal".

Yes, some people say 650b wheels allow you to have the speed of the 700c wheels without having the sluggishness of the 700c wheels in corners while. So, this implies 26 inch wheels would be slower. They also say it's easier to roll over grass, roots, rocks etc. with 700c. So, 650b would likely be easier to roll than 26 inch as well. I can certainly see your interest. But, if larger wheels are faster and roll easier on grass, snow, I'm leaning now towards 29ers or large-tire hybrids or touring bikes (like the Nashbar touring frame allows even 700x45mm tires, I tried it). Besides, I could not find Michelin Tracker and Continental TourRide tires in 700x2.2 inch. Since I'd prefer semi-slicks (not slicks like Fat Franks), that means 29ers would be out of the picture leaving only a touring bike with a frame from Nashbar and/or larger tire hybrids. I now believe I might end up with a touring bike with rigid forks and maybe later a city/rain/winter hybrid bike with suspension forks and studded tires (at least in the winter). Bike24 and Bikexperts in Germany have trekking (flatbar touring) frames.

650B rims are 584mm in diameter and 26" MTB rims are 559mm in diameter. That's only 1" difference which is 1/2" on each side. If that makes you feel like you're "crawling like an ant" then just use 12mm wider tires and the overall diameter will be the same as using 650B rims.

Although I'm gonna guess it wasn't the wheels that were making the bike feel "TINY", but the gearing (because all else equal smaller wheels = lower gears). Just put on some bigger chainrings and you should be set.

Thanks for the info.

In response to people who called me 'he', I am female.

The bike felt small when converted to a touring style because I put 1.5" Panaracer slicks on it. I also put on a short (60mm) Nitto Stem with Rando bars. The difference between that set up and a standard quill MTB stem / bar setup was huge. Id been using a 100mm long MTB stem with and upward angle, and bars with a 2" rise. I'd also had a shock fork on it for a while. All of this, combined with 2.1" knobbys, made the bike feel very upright and I'd say it fit me very appropriately as a Mountain Bike. The drop bar set up brought me much closer to the top tube and the slicks and straight fork brought it closer to the ground.

I'm really just exploring my options here... I wasn't looking for lectures. I love this frame and was wondering what options may be for making it a touring frame. I work as a mechanic, I'm aware of all the options out there in terms of new bikes and I'm not interested in them.

@ Fred Smedly, My MB3 is an '89. As I stated, I put 700c wheels (w/ 25mm tires) into the frame and it fit with room to spare. I was amazed. There is no reason this frame wouldn't accomodate 650b's.

What I really wanted to know is if the brakes would line up with 650b's. I now know they wont, though I have learned the bosses can be rebrazed for pretty cheap.

Those of you who want to talk someone out of a conversion like this should check this article:
https://velo-orange.blogspot.com/2011...t-to-650b.html
It explains a lot about why someone would opt for 650b's on a touring bike and shows that it can work pretty well.

If you'd like higher bars I'd look into a Nitto Technomic stem.

Convert if you'd like but the cost/benefit just doesn't make sense to me personally.

And MB3 frame modification makes me kinda sad

I cheched the wheel/tire diameter of my michelin country rocks mounted to mavic 231s and it's 655.

Maybe my tastes aren't as refined as VO blogger dude's but they ride fine and are inexpensive and easy to find

I missed the part about using a MB3 with road tires. I personally would pass on this as the Geometry is not designed with that in mind IMO. Nonetheless I have seen Paul motolite canti's successfully used with stock canti mounts as well as these; https://www.canecreek.com/component-o...direct-curve-3
The Paul's are very spendy as the retro high end MTB crowd like them.

Grant Peterson's touch isn't magic, they were produced by the thousands in an Asian factory.

Still, modification seems a little drastic. Even if you get the mounts rebrazed, you need a repaint afterwards. Depending on the hand behind the torch, I can't imagine it would cost you less than $150. For that you get a lingering sense of guilt for modding a frame, a fancy new color, steering geometry optimized for a very different wheelsize and a price tag that's a third of the way to a new 650b bike.

Hahaha, well I'm not a GP fanatic as much as I am a 90s steel MTB fanatic, especially lugged ones.

I'd be just as sad to see a modified Trek 9xx series, Bianchi Grizzly, Specialized Stumpjumper, KHS Montana, etc...

If it was a bit further down the line I wouldn't cry. Take an MB-5 and tallbike it for all I care.

Being a bit of a thumbshifter fanatic I'm also kinda tearing up over what might be the fate of some Shimano DX (or similar) thumbshifters.

Thank you! This is really all I was looking for .