Vaughan51

My bike packing / gravel bike has 29" wheels (Salsa Fargo) so I've got a bunch of spare tires and tubes. I just bought another gravel bike which has 700cm wheels (Kona Libre) with much narrower tires. I'm thinking I should still be able to use my 29" tubes as spares for this bike? ( Only the tubes as the tires are much narrower on this bike).

Does that sound reasonable? Are there any watch out for if I can do this?

Thanks

katsup

Depends on how much wider the 29" tubes are compared to the 700c. You can usually get away with a tube a little outside the range it states, just be careful when installing. The answer is maybe.

700x50c = 29x2.00

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SpedFast

Just make sure you lay them in evenly when installing because it will feel like you have a lot of extra rubber squeezed in there. But they will work, at least until you can replace with the proper sized tube, or not.

ThermionicScott 

Just for the record, the "C" in 700C does not stand for "cm". That would be quite a large wheel.

Vaughan51

Good point that was an "oops". When I did a google search I got a little autofill which I carried forward (LOL)

Vaughan51

Okay looks like we are in business.

Last year with bike parts hard to come by I could not find a spare tube in any of the local bike shops and they talked about a rubber shortage. So I ordered online and there was pretty good pricing if you bought a 3 pack. Which (Murphy's law) went missing in transit so ordered another and guess what "ALL" showed up in the mail. It could be awhile before I need to buy more.

curbtender

A friend bought spare tubes for their 32/700 tires. They were marked 32-50 wide. That was ludicrous.

TPL

700c ( not 700 cm )
700c and 29er are the exact same size ....622 ....only difference is that 700c was in use for more than 80 years prior to the 'creation' of 29er
29er is a marketing ploy that some madison avenue, huckster-type created
I got a bridge in nyc that I want to sell ....it used to be called the brooklyn bridge, but I'm not gonna call it that ( might hamper the sale by making it appear too common ) ....so, I'll just call it the Manhattan - Brooklyn connector bridge ....yeah, that's the ticket !....can you hear the sizzle ?, can you smell the snake oil ?, are you mesmerized by all of the smoke and mirrors ?
Cha-ching !
All 29er believers, prepare to have your billfolds massaged !

SpedFast

While indeed they are the same diameter, I always think of 29ers as MTB paraphernalia=more rugged and heavy. While 700c's make me think of tall and slender.

Vaughan51

So furthering my quest on exchangeability between 700c and 29". I got a good deal on a couple of Pirelli Cinturato M tires 700c sized and I was thinking that I might try them on my 29"rims which are on my Salsa Fargo.

Any watch out for's if a person was to do this. I know the Pirelli tires are a little skinnier than my Vitittori Mezcal's but I don't see that being a problem.

Just thinking of options given the supply chain for bike parts isn't back to normal and wanting to shop local if at all possible.

Thanks

Iride01 

Probably not, I've put a 622 x 23 trainer tire on my son's 29'er that we use on the trainer while indoors. It has a 622 x 20 mm rim on the rear. Normally for outdoors that would be a 622 x 54 mm tire which is advertised as 29" x 2.20" as part of it's name in the big white letters on the sidewall.

For real cycling not on a trainer I might be a little leery of running tire that is close to the same width or less than the internal width of the rim. So I'd either tone down how aggressive my riding is till I figured out how well it handled, or I just get a wider tire.

Also, running those narrower tires on too wide a rim might expose you to more rim damage if you should ever flat.

Learn how to find the ISO sizes of tire and rim and you won't have to wonder what will and what won't so often.

As to your original OP, tubes should not exceed the inside diameter of the space created by the rim and tire. If they wrinkle and you ride them then that will be a point for wear on the tube and you'll probably flat sometime in the future. Tubes usually come in a size range of widths they'll work in and sticking to that ensures the tube will not be over size for the tire. But for times I don't have the proper tube, I'll put anything I can stuff in there so I can get to where I have to get.

ThermionicScott 

Many "road 700C" rims are now as wide as "29er" rims used to be, so I predict smooth sailing.

Vaughan51

Excellent, looks like we are going to be in good shape then.

Vaughan51

I will check out the ISO sizes of tires - thanks for the tip and Also the rim widths between my two bikes. I've been waiting for 3months for a couple of Mezcal's, when I happened into a local coffee shop then going next door to another bike shop and the Pirelli's were just sitting on the shelf.

VegasTriker

One thing to consider when buying tubes is ease of installation, particularly when you have to switch the tube out on the road. It can be really difficult to install a wide tube in a narrow tire even if it might work. When I purchase tubes for the 700C X 23 rear tire on my recumbent trike I always look for ones that are rated for 700C X 28 to 32 over tubes rated for 700C X 32 to 35. The difference seems small and both tubes will work OK but it seems to be far easier to get the narrower tube in the tire quickly. As far as loss of air as the tire sits, it doesn't seem to make much difference.

A very good tutorial on tire size: https://www.sheldonbrown.com/tire-sizing.html

Iride01 

This is a good read if you are uncertain about bicycle tire sizes. Old, but still applicable....

Tire Sizing Systems

There is even a table near the bottom that shows recommended rim widths vs tire width. Though that isn't a set in stone thing. It just a general thing when you have no better info. Some manufacturers like Continental Bike Tire have similar charts for their tires. Or if you are up to the task and okay with the risk, then you can test and try any combo you care to choose.

Vaughan51

I looked at the charts and there is some overlap on my two rim sizes so I’m good on both the tires and tubes. Although I’m going to go a little narrower on my Salsa Fargo to achieve the overlap.

thanks

msu2001la

Inner tube sizing has always seemed unnecessarily specific to me. Inner tubes are very stretchy. A standard "road" tube is usually labeled as 20-25c, but with just a few lbs of pressure it will balloon out to several inches if not inside a tire. When installed, the tube is contained by the tire (and rim bed), so it's not going to stretch out. A standard 20-25c road tube has zero problems filling out 28-32mm tires.

I suppose a road tube in a 2"+ MTB tire might be more of a problem, but I feel like even that would probably work OK.

Rdmonster69

I think the only issue is that smaller road tubes become thinner when filling out larger tires. This may make a difference when it comes to flats. A road tube for larger diameter tires will maybe be thicker at the specified size.

msu2001la

I'm sure wider tubes are thicker, I just don't see how that could possibly matter if we're talking about the size difference between 25mm and 32mm tires. Maybe the tolerances are way tighter than I realize. It just seems like a bit of a stretch to think that an extra 7mm of width would really make any actual difference in terms of flat protection, considering how stretchy and thin inner tubes already are, and that whatever is piercing the innertube has already pierced the tire itself.

Rdmonster69

I agree, Just something to think about. That .01 mm may be the difference LoL !!

Iride01 

The more a tube has to stretch to fill the inside of a tire, the more it'll act like a balloon being introduced to a pin when getting a puncture flat. Slow flats are a nice thing. I like them better than the fast flats which sometimes force me to stop where I don't want to stop.

That being said, I'll still use a undersized tube before an over sized tube if I have to make a choice.

Vaughan51

Hadn't thought about tube ease of install but I can see where that would be important - thanks for the insight.

jaxgtr

I have those tires in 40mm on some Bontrager Pro37's that are 21 internal, but have also run this on some Pro3v's that were 25 internal and they ran fine running tubes that were size 28-35mm

BlazingPedals

The 29er fad was no worse than the 650B fad.