yannis

I want to upgrade my bicycle's wheels with a larger pair. I am quite sure that I will use a 700C wheelset. On the market I can found many different sizes like 700 x 28C, 700 x 32C, 700 x 37C that can also be found respectively as 28-622, 32-622,and 37-622. In the second case the names are the bead seat diameter-rim width, in the first case they are all 700C with different rim widths, right? Does all these wheels have the same diameter (including the tyre) and which is it? Is it 622+(2 x rim width) for all of them or 700 mm regardless the rim's width? I want to know the exact diameter of the wheel, with the tyre on the rim and inflated, in order to be sure that it fits on the frame leaving the proper clearance. Any advice could be very helpful!

KevinF

https://sheldonbrown.com/tyre-sizing.html

yannis

I have already this article, but I am a little confused...
All 700 (in french size) wheels (700A, 700B, 700C) have the same diameter, with the tires on them, and this is 700 mm?
If so what about 700 x 28C, 700 x 32C, 700 x 37C ? They also have 700 mm diameter?
The 700C French size has a 622 mm BSD in ISO, so the standar should be to have a (700-622)/2=39 rim width, right?
The sizes mentioned above (700 x 28C, 700 x 32C, 700 x 37C e.t.c.) what Bead Seat Diameter do they have?
I hope I was clear...

HillRider

As you noted 622 mm is the bead seat diameter for all "700c" rims and the 700 number has no basis in current sizing terminology. 700c is the only version currently made and 700A, etc are long obsolete.

The second number (28, 32, etc.) is the tire width in mm and, since most bike tires are roughly circular in cross section, it's also very close to the tire's height. So to a good approximation, the overall wheel diameter will be 622 + 2x tire width. For a 700x28 tire the overall diameter would be about 622+2x28 = 678 mm. Various width tires, within reason, fit on the same rim width which is commonly about 13-15 mm (inside width) for most road rims and does not enter into the overall diameter calculation.

FastJake

Did you mean wheels or tires? Do you have a plan for attaching brakes to this with the larger wheel size?

yannis

So, they a 700 x 28C wheel should have 622+(2x28)=678mm diameter, the 700 x 32C, 686mm diameter and the 700 x 37C, 696mm with the tire on it, right?

And these sizes refer to the tire and not to the rim, the only rim I can find on the market is one and the same for all these tires, is it true?
How could I identify this rim, I mean which is its name, its size, how could I find it in the market?

If it isn't so the rims for 700C wheels are many and different, but the have all the same Bead Seat Diameter which is 622 mm. They also should be named with a second number which identifies the proper tire width (rim width).

Which case described is true, the first or the second?
My opinion is that the second one is true, but in many, inferior class, stores, the rims are all described as 700C and you can fit on them any tire you want...

Retro Grouch 

What, exactly are you trying to accomplish?

The easiest way to tell if larger wheels will work with your bike is to borrow a wheelset the size you are considering and trial fit it onto your bike. Areas where problems frequently occur include:
1. Diameter at the bottom bracket shell and fork crown.
2. Width between the chainstays near the bottom bracket. Don't overlook the front derailleur if you have one.
3. If you are using rim brakes, brake reach can be an issue.
4. Rear dropout spread.

My 700c own fixed gear conversion started life as a 26" mountain bike. The rims and tires just happened to fit the frame and a standard reach 105 caliper brake fits perfectly to the reflector mounting hole on the fork.

yannis

Could you please be more specific about that?
Do you mean that larger wheel produces greater forces that may damage these parts? Or is it something else?

shelbyfv

Tires vary in size, even if nominally the same. One tire in 28mm may be smaller than another in 25, for example. If you are thinking of getting a fatter tire, check the size of what you have now, then look at the clearance at the chainstays and fork. You should be able to determine if there is any chance a larger tire will fit. After that, it's trial and error. edit=OK retrogrouch said it all. Check for physical interference in those areas.

Retro Grouch 

That's one of the places where it's likely to rub. And wider tires are more likely to rub than skinny tires. Sometimes, if it just barely rubs, you can make it stop just by installing a real skinny tire.

HillRider

Yes, that's correct

The term "700c" refers both to a rim defined as having a 622 mm bead seat diameter and to the tires of varying width that fit it. All 700c rims are 622mm BSD and all 700c tires fit that same diameter rim but can vary in width.

I'll second RG's question as to what you want to accomplish by using "larger wheels". Wider tires can run lower air pressure and ride more comfortably but weigh more and may have more rolling resistance. They may also give clearance problems if your frame and fork weren't designed to accept them. Again, what do you want to do by going larger?

dbg

If your current wheels are 700c, you're kinda stuck with that size rim. Anything different will cause problems with the brake pads. Also if your current bike is a roadie with 700c x 23 or 25, then you probably can't go any bigger. Most modern road bikes won't even fit 700c x 28. You're not totally out of luck. It is just likely a much bigger project than simply putting significantly larger tires on your current rims. If the bike originally had 27 inch wheels, you could replace them with wide 700c rims and maybe 32 tires (and some extended brakes).

We'd need to know exactly what your current bike specs are to know what your options might be.

FastJake

+100

What are you trying to accomplish with "larger wheels"?

Not having a basic understanding of tire sizing, you are not ready to undertake this kind of project. Too many variables, you will almost certainly buy parts that will not work with what you have, and may not fit in your frame/fork.

Changing the wheel size on a bike rarely makes sense, and only if you know what you're doing and have a specific goal in mind (like Retro Grouch's cool fixed gear.)

yannis

Ok, let me be more clear!
The wheels that are on the bike right now have 26 x 1 1/2 x 1 3/8 rims. That in ISO should be 37-584.
But the tires are 40-584.
The bike is old enough and the wheels also. That's a reason I want to change them.
A second reason is that I want to upgrade the rear derailleur and freewheel and it should be better to change the whole wheel as it is old enough and needs to be serviced.
The clearance between the tire and the installed fenders is about 35mm.
The wheels seem to me small for this frame and as I have to replace them, I thought that I could do that with a larger pair.
So I am trying to find how could I identify the diameter of the whole wheel, with a tire installed, in order to be sure that it fits on the frame without problem. I am not thinking about using fenders.
The basic reason is aesthetic.

shelbyfv

Borrow a couple of wheels and see how they fit. You will also have brake issues to resolve.

fuzz2050

Strangely enough, in this case, tire size is second to rim size. Your first concern is going to be brake reach, that is the distance from the brake mount to the sidewall of the rim. Changing wheel (Rim size, to be specific) can have a dramatic impact on brake reach, and require either completely new brakes, or even a completely new style of brake (See Retrogrouch's example).

Your first step should probably be borrowing a set of 700c wheels and measuring the distance from the brake mount bolt to the sidewall. You're going to have an increase of 19mm (by my math, but it should be double checked). If you have room in your current brakes to move the pad 19mm, you should be ok to do a straight swap. Otherwise you're going to need a new set of brakes as well.

Edit: Are you sure about the 584 BSD? If that's the case, then you have what is (more commonly) designated 650b, and should have a number of replacements available. All else being equal, it's easiest to keep the rim diameter the same.

yannis

The existing brakes have long reach, but they are a little rusty and I will replace them. So If I choose a larger wheel set I could use short reach brakes.
The frame has no mount points for disc brakes.

I am sure that the rims are 26 x 1 1/2 x 1 3/8, it is written on the rim. This is corresponding to 37-584 according this table. The tires are a little wider 40-584.

ThermionicScott 

I think you should stick with it -- 650B is pretty "in" these days.

(I partly say that to keep from trying to buy the wheels off you. )

fietsbob

There is a 700 a, and b, as well as a 700c, It's a French sizing system...


each is a different rim /tire combined..
likewise, a 650 a,b,c..

HillRider

700A and 700B are museum pieces and have been for decades.