Tube size question, please

SoCalSteve · #1 03-04-2021, 10:17 AM

Hi all,

Is 650b the same as 27.5 when it comes to buying tubes?

Thank you in advance!

Steve

recarcar · #2 03-04-2021, 10:21 AM

Quote:

Originally Posted by SoCalSteve

Hi all,

Is 650b the same as 27.5 when it comes to buying tubes?

Thank you in advance!

Steve

Yup! When labeled 27.5 they just tend to come in larger sizes but it's no problem finding 27.5 in 42mm (1.75).

SoCalSteve · #3 03-04-2021, 10:24 AM

Quote:

Originally Posted by recarcar

Yup! When labeled 27.5 they just tend to come in larger sizes but it's no problem finding 27.5 in 42mm (1.75).

Ok, one last question...I want to run 28’s. What would the tube spec be for this width tire?

Thanks!

Wattvagen · #4 03-04-2021, 10:26 AM

really?

what kind of a bike is this?

650Bx28 is a bizarre tire size. what tires even come in that size?

recarcar · #5 03-04-2021, 10:30 AM

Quote:

Originally Posted by SoCalSteve

Ok, one last question...I want to run 28’s. What would the tube spec be for this width tire?

Thanks!

I'm not sure 650b x 28mm tubes are very common or even made? You have tires is 650b x 28? I could be wrong but it seems the smallest semi-common size tire in 650b is usually 38mm, and even then I don't see them super often. 42mm and up seem to be the most common sizes.

SoCalSteve · #6 03-04-2021, 10:43 AM

Quote:

Originally Posted by Wattvagen

really?

what kind of a bike is this?

650Bx28 is a bizarre tire size. what tires even come in that size?

It’s a e road/gravel bike that I bought on close-out. It comes with 650b tubeless tires and I will be using this bike specifically for road, hence the wish to go with 28’s.

Continental GP5000 comes in 650b x 25 and 28.

I eventually will have a wheelset built that is 700c for it. But for now I will ride it with the 650b’s.

SoCalSteve · #7 03-04-2021, 10:46 AM

Quote:

Originally Posted by recarcar

I'm not sure 650b x 28mm tubes are very common or even made? You have tires is 650b x 28? I could be wrong but it seems the smallest semi-common size tire in 650b is usually 38mm, and even then I don't see them super often. 42mm and up seem to be the most common sizes.

Continental GP5000’s come in 650b x 25 and 28.

The bike shop is swapping out the much wider gravel tires for the 28’s. I just want a spare tube, in case. Eventually the wheelset will be swapped out for a custom built 700c wheelset.

What do you suggest I do for a spare?

Thanks!

Mark McM · #8 03-04-2021, 11:02 AM

Quote:

Originally Posted by SoCalSteve

Hi all,

Is 650b the same as 27.5 when it comes to buying tubes?

Thank you in advance!

Steve

650b is a now obsolete French size, and 27.5" is just a quaint industry term anyway (that was made up by marketers to make an already existing size sound new), and both now only exist advertising literature. Both names refer to the current ISO/ERTRO 584 mm standard. All tires (and most tubes) are imprinted with their ERTRO sizes, so you're looking for tubes that are labeled www-584 (www is tire width).

DRZRM · #9 03-04-2021, 11:14 AM

I for one would like to see a picture of a bike that fits you rolling on 650b x 28 tires. I'm having trouble imagining it. Seriously, can you post a pic?

recarcar · #10 03-04-2021, 11:22 AM

Quote:

Originally Posted by SoCalSteve

Continental GP5000’s come in 650b x 25 and 28.

The bike shop is swapping out the much wider gravel tires for the 28’s. I just want a spare tube, in case. Eventually the wheelset will be swapped out for a custom built 700c wheelset.

What do you suggest I do for a spare?

Thanks!

I see! No idea 650bs were produced in that size! Since it's such an uncommon size I would look around for continental-made tubes. If they make the tires in that size I would assume they make the corresponding tubes. I would also like to see some pictures!

prototoast · #11 03-04-2021, 11:23 AM

Quote:

Originally Posted by SoCalSteve

It’s a e road/gravel bike that I bought on close-out. It comes with 650b tubeless tires and I will be using this bike specifically for road, hence the wish to go with 28’s.

Continental GP5000 comes in 650b x 25 and 28.

I eventually will have a wheelset built that is 700c for it. But for now I will ride it with the 650b’s.

If the bike was designed for large volume 650b or 700c, it's probably not going to handle quite right with 650x28 tires.

For tire diameter, 650bx47 = 700cx28. 650bx28 is going to put your bottom bracket 19 mm lower. If it's a high bb to start with, you might be okay, but lots of gravel-ish bikes set up for 650b aren't super high, and could put you dangerously low if you ever like to pedal in corners.

Also, you will significantly reduce the trail, making the bike steer much quicker. If that's what you want, that's okay, but if you like how it handles now, you might not with smaller tires.

recarcar · #12 03-04-2021, 11:26 AM

Quote:

Originally Posted by Mark McM

650b is a now obsolete French size, and 27.5" is just a quaint industry term anyway (that was made up by marketers to make an already existing size sound new), and both now only exist advertising literature. Both names refer to the current ISO/ERTRO 584 mm standard. All tires (and most tubes) are imprinted with their ERTRO sizes, so you're looking for tubes that are labeled www-584 (www is tire width).

For this case, I think it would be wise to look at the ERTRO sizing because just from a cursory search for tubes in 650b x 28mm, it looks like most tubes that come up are in the 650c (571mm) size. Just make sure that it's marked 584mm otherwise you might end up with a 650c tube.

Mark McM · #13 03-04-2021, 11:31 AM

Quote:

Originally Posted by Wattvagen

650Bx28 is a bizarre tire size. what tires even come in that size?

Continental and Schwalbe make 650b tires in widths down to 25mm, so somebody must be riding them. And these aren't just the odd niche model, there are Continental GP5000 and Schwalbe Pro One available in 25-584 and 28-584 (that's "650x25b" and "650x28b" for those who prefer obsolete nomenclature).

recarcar · #14 03-04-2021, 11:33 AM

Quote:

Originally Posted by prototoast

If the bike was designed for large volume 650b or 700c, it's probably not going to handle quite right with 650x28 tires.

For tire diameter, 650bx47 = 700cx28. 650bx28 is going to put your bottom bracket 19 mm lower. If it's a high bb to start with, you might be okay, but lots of gravel-ish bikes set up for 650b aren't super high, and could put you dangerously low if you ever like to pedal in corners.

Also, you will significantly reduce the trail, making the bike steer much quicker. If that's what you want, that's okay, but if you like how it handles now, you might not with smaller tires.

Definitely. I totally understand if the OP wants to experiment with 650b x 28mm but these are all great points. If you just want to go with skinnier tires a 700x25-28 would probably fit if it has room for larger 650b tires and would not alter the geometry much. You might want to try a 700c wheel in there if you have one, as it's going to be much easier sourcing tubes/tires and all the above benefits of not altering geometry if that is what you want to do.

recarcar · #15 03-04-2021, 11:36 AM

Quote:

Originally Posted by Mark McM

Continental and Schwalbe make 650b tires in widths down to 25mm, so somebody must be riding them. And these aren't just the odd niche model, there are Continental GP5000 and Schwalbe Pro One available in 25-584 and 28-584 (that's "650x25b" and "650x28b" for those who prefer obsolete nomenclature).

I have never seen one out in the wild. Now I'll be on the lookout, haha!