When to consider going to the dark side of 650b?

[NHAero]

I had my Bingham built for 650Bx38 as the basis of design. It will accept up to 650Bx48, buut I've only run either 38 or 42. In my size frame (55 ETT) I get toe clearance with 38s and fenders, which I like on routes that may include some jeep roads or singletrack. I also have 700C wheels for this bike, but run them with 25s. I could likely fit a 700Cx38 in there if needed. The 700Cx25 setup has very close to the same trail and flop as the fatter 650B tires.

Even accepting that 700C might be faster, I wonder by how much assuming the same tire size and type. The comparisons I've seen with 700C usually have a fatter 650B tire.

I have found 650B wheels a bit easier to pack in a bike case than 700C.

All of these are marginal benefits but they made sense to me for my use case. I'm helping my sister get a bike built and she's shorter than i am and 650B seems like a good choice for that bike too.

I run GK slicks.

[YesNdeed]

Originally Posted by ridethecliche

What use scenarios have you found that dropping to a 650B is worth it?

For giving it a MTB bias. At the time I built my current gravel setup, it was the only thing I had to ride on dirt. I fit Conti Cross King 2.2s, and hit the trails. It handles well on most any trail in the area, especially with super flared, shallow drop bars, with the inevitable dismount on rock gardens and steeper grades. But now I have a proper full squish 29er, so I switched to GravelKing slick 1.9s (tan walls FTW!). I don't have compatible 700 wheels and don't want to spend the money on more wheels, so it's been a practical way to make it roll faster. I'm loving the result as it has become my daily driver, ride to work kind of bike. It's super versatile and taking routes with a mix of smooth and rough surfaces is a blast!

I had 3T 650 wheels laying around so the choice was easy for me.

Edit: when riding gravel only, especially when riding with other people, it felt a bit heavy and over-biked though.

[klink]

Been pondering this same question lately myself. Just recently set up a new set of 700c rims that are wider, tubeless and roll faster than what I had before. This leaves me with the old hubs that I thought I'd re-lace to a set of 650b rims to try the bike out with a larger 47-50mm tire.

Any recommendations for a basic tubeless 650b rim? Was looking at WTB KOM i23/25/30s, but for $50 per rim there's also carbon rims via Light Bicycle...

[.RJ]

Originally Posted by thwart

Going to 700c would increase trail even more and give me something further away from my customary road bike type handling.

Unless you put a smaller 700c tire on it.

[thwart]

Originally Posted by .RJ

Unless you put a smaller 700c tire on it.

Like a 700 x 28 or even a 32?

Kind of redundant as I’ve got that covered with my other bikes.

For me a disc ‘gravel bike’ is primarily to allow running some fatter rubber.

[ridethecliche]

Originally Posted by Davist

I have both, for dirt only, I think 650's are better. Trouble is most gravel here is at best 50/50. When riding with our group, it's usually not technical and they have lots of horsepower so the 700s with semi slick 43s work well. I can keep up with the thunderburts (they do roll very well) but don't seem to carry the momentum the bigger diameter wheels do. In the winter, my gravel bike is my main bike, so I've decided to keep it simple and I'm selling off the 650s (in classifieds if you're interested)

I messaged you on Facebook and yup I'm in south Philly!

[robt57]

Originally Posted by whatshubdoc

I think these days it’s when you want to run 2.1-2.3” meats.

Agree. Even my old Gary Fisher Paragon 29er once converted to 650b gets used way more. Took the truck feel right outta it.

Just watch BB drop of bike you are considering the change for. The 29er not any issue. My Strong Allroad Carl built in 2015 has super low BB, IMO too low for running 650b. [for my druthers] Especially with a wide Q chainset, I have MTB/XT on it. Carl told me I made a MTB outta it.

Even get some cheap pulls wheels off PL or CL to see before getting spensive wheels would be my advice.

[ridethecliche]

Originally Posted by robt57

Agree. Even my old Gary Fisher Paragon 29er once converted to 650b gets used way more. Took the truck feel right outta it.

Just watch BB drop of bike you are considering the change for. The 29er not any issue. My Strong Allroad Carl built in 2015 has super low BB, IMO too low for running 650b. [for my druthers] Especially with a wide Q chainset, I have MTB/XT on it. Carl told me I made a MTB outta it.

Even get some cheap pulls wheels off PL or CL to see before getting spensive wheels would be my advice.

Thanks for the advice.

I want to see how big of a tire I can fit on the tcx in 700. I have a feeling that going to 650 would only net me a few mm at most. Maybe 700x45 as measured vs 650 x 51mm (2.1?) as measured.

My TCX has a bb drop of 60, which I think is good for 650b conversion, yes? My TCR is 67 in contrast.
So the bike will be maybe about 1.2cm lower with 650b? Not sure my math is right here. But difference in radius between 700 and 650 is 19mm right?

[Hilltopwalters]

I'm also out here wondering what a 650b conversion on my Serotta will end feeling/looking like. Paul Mini Motos in the front and V.O. Grand Crus in the back. This place gives me ideas I don't need banging around in my head.

[tellyho]

I have 650x48 knobbies on my gravel bike for underbike routes. 700x42 for plain ol' gravel. I like having the options; I do notice the difference in traction and cush even with only 6mm difference. Part of that is the 48s are on 30 ID rims - they are super stable.

[bigbill]

A frame builder friend has a few Max tube sets. Because of my height, if he were to build a gravel bike for me, it would be 650 because of the maximum tube lengths. Still thinking about it.

[mhespenheide]

Originally Posted by Hilltopwalters

I'm also out here wondering what a 650b conversion on my Serotta will end feeling/looking like. Paul Mini Motos in the front and V.O. Grand Crus in the back. This place gives me ideas I don't need banging around in my head.

I strongly suspect that if you have mini-motos, you won't be able to change to 650b. Mini-motos use a canti-style braze-on to attach the brakes to the frame and you can't move them down (or up). If your canti posts are removable, there's a hack to get around this. But most canti posts are not removable.

But maybe I'm just being an armchair internet expert and you've already checked all that out?

[owly]

Originally Posted by klink

Been pondering this same question lately myself. Just recently set up a new set of 700c rims that are wider, tubeless and roll faster than what I had before. This leaves me with the old hubs that I thought I'd re-lace to a set of 650b rims to try the bike out with a larger 47-50mm tire.

Any recommendations for a basic tubeless 650b rim? Was looking at WTB KOM i23/25/30s, but for $50 per rim there's also carbon rims via Light Bicycle...

Kinlin may have a cheaper 650b.


Older pics of carbon TCX I've seen mention a safe 50mm rear / 2.1 up front.

A while back I thrashed around on 2.1 ThunderBurts for a bit. My main [con] take on going back and forth between 27x2.1 and 700x48 with a carbon fork:-
The steeper front end with the 27.5, along with the shorter wheel radius, made me want to get back on the saddle a smidge / ride with a lighter hand, so the hits across the rougher stuff wouldn't come through as much vs a big 700c.

[sparky33]

Originally Posted by Hilltopperny

My experience is that 700c is faster in most use case scenarios of a gravel bike, but 650b is more comfortable and better/faster on rough descents and most single track. There is more tire patch contacting the ground giving it a bit more stability.

I like 650b set ups for the times where speed isn't necessarily the main objective, but a 700c with 48-50mm tires do give plenty of cush and are faster in almost every way.

This^ is about right.

I split my time 50 50 between the wheel sizes, I go back and forth on my preference for 700c or 650b. For sure, I like my 650b tires 7-8mm wider than 700c for a given purpose.

This summer I ran 700x45s where I have typically run 650bx2.1s. The experience was equally enjoyable

[sparky33]

Originally Posted by ridethecliche

What use scenarios have you found that dropping to a 650B is worth it? Honestly I'd have to test fit to see how things play out but there's more room back there than I anticipated for 650B

Dropping to a 650b wheel/tire set will give you a wider footprint and lower gear inches. This can be a convenient solution in some cases.

For those 650b-curious folks, I suggest getting a 650b wheelset and messing around with various tires. At the very least, it is a fun experiment.