Hi I’m a very novice home bike mechanic but was curious about converting my 700c Masi CXGR into a 650b setup I saw in an article on bikepacking.com. The article (which I can’t seem to include) has a link to a WTB official list of compatible frames that includes the CXGR.

My question is, if I want to keep all the same Shimano 105 11 sp road shifter/derailleur/cassette system, do I just need to find a 650b road wheelset? They seem to be hard to find but maybe I don’t know what I’m looking for. Or would it be possible to go with some 650b mountain bike rims I already have and swap for a long cage road derailleur and an 11sp mtb cassette?

i don’t know the first thing about building wheels and was hoping to avoid that so wanted to purchase or repurpose some prebuilt wheels. Any advice/guidance much appreciated.

Should be a straight swap, just need a rear hub with the same spacing.

Masi doesn't list that spec but I'm guessing it's 135mm rear spacing. There should be lots of options out there. If you can't find one (which I doubt), you can easily find someone to lace a 135mm hub to a 650b rim for a reasonable cost. >$500.

Shouldn't need to change components unless you go to a bigger cassette.

Welcome to the forums! Pacenti sells complete 11-speed 650B wheelsets for a pretty decent price. If I were building up a modern roadie on 650B wheels, they would be my first choice.

Rim brake: https://pacenticycledesign.com/colle...1speed-shimano
Disc brake: https://pacenticycledesign.com/colle...isc-brake-650b

Great, thanks for the help!

What's the matter with 700c? I assume you've already got

To run wider tires?

-Matt

Because he can? Why does he have to justify it?

The biggest issue will likely be brakes, unless you have disc brakes. If you have rim brakes, you'll probably need longer reach calipers to allow the brake pads to reach the rim.

Do you have 650b rims, or an actual wheel set? The Masi website says that your frame has 12 mm thru-axle in the rear. If you have an actual wheel set, check to see whether it's a fit.

I did the same conversion almost three years ago, and it's been one of the most fun conversions I've ever done.

So as for the 650b rims, yes they are full wheels (135mm spacing as they are MTB). The front wheel slips onto the frame perfectly, and the back wheel seems to slide into place as well (the rotor doesn’t quite fit in the brake but I’m assuming that can be adjusted or replaced). But my 11 so road cassette won’t fit on the MTB wheel’s freehub body. Is it possible to change the freehub body so it would fit on there since the wheel otherwise fits into the frame?Excuse the ignorance I just have no experience here

The issue is that the road cassette is 1.85 mm wider than a mountain freehub body, right? I'm getting out of my depth here due to my lack of direct experience w/11-speed kit, but some searching on the forums suggests that a SRAM 11-speed hub will fit a Shimano mountain freehub. So you could look at the SRAM PG-1130 in 11-26 gearing, and maybe that would fit within the range of your current derailleur. Another idea if you just want to run a quick test is to set aside one of your 11-speed cogs and use some spacers to run the other 10 cogs of your current cassette and set limit screws to prevent over shifting. That's hack that I would personally have a go at, but I wouldn't blame if you didn't want to go there.

Hopefully someone with more direct experience will chime in.