Bicycle TutorBicycle Tutor

Show off your bike!

Related video tutorials:
Confusing tube sizing
#1
My son's bike has these numbers on the tire: 700c X 40c 28 X 1 5/8

My son's complaint about the tubes that I buy, that should work based on these numbers, is that when he inflates the tube, then it pokes out from underneath the tire. So what size should we buy, and any suggestions of where to find it? Looking online, it looks like 700c is often equated with 27".
And tied into this question is, he hasn't ever used a liner, but he has frequent flats. I'm thinking of getting a couple of liners, but do you have to adjust the tube size when you use a liner?

Thanks for your help!
Reply
#2
Get yourself a 700C liner (real name is rim tape)

Then a 700C X 40 tube...
Reply
#3
(08-27-2013, 02:27 AM)bobtravers Wrote:  Get yourself a 700C liner (real name is rim tape)

Then a 700C X 40 tube...

Bob I think he means liner as in tube puncture protection, rim tape is used to cover nipples and holes under the tube. He wants to know about the liners used between the tube and tire. If the tube is popping out of the tire then there is a bead seat issue, this can be caused by many things.as far as tube liners I do not use them but others here ( Nigel) would be happy to tell you about them
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
Reply
#4
Hi Diane;

Poking out from under the tire means that the tire has not been properly seated on the rim as PK said above.

Liners; I like STOP FLATS 2 liners, which are color coded to the tire size. This page has the color codes clearly defined, but I purchase them from Amazon. For a 40mm tires; I would suggest Gold or Tan. Here is GOLD: http://www.amazon.com/STOP-Flats-Bicycle-Tire-Liner/dp/B001CJZ3WI/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1377576895&sr=1-1&keywords=stop+flats+2+gold

Tires; we run these tires on our tandem:
http://www.amazon.com/Kenda-700X35-Kwest-K-Shield-Blackskin/dp/B006GEZSKG/ref=wl_it_dp_o_pd_S_nC?ie=UTF8&colid=13X4M4RTA6L5I&coliid=IQJMGCVOU78AJ
which have a multitude of numbers on them:
37-622 700x35c 28 x 1 3/8 x 1 5/8
they are 35mm (1 3/8") wide, 41mm (1 5/8") tall (bead seat to tread) and fit on a rim with a 622mm bead seat diameter. 700c, most 28" and 29" tires fit on a 622mm bead seat diameter. 27" tires fit on a 630mm bead seat diameter rim - yes larger (go figure). Here are some details: http://sheldonbrown.com/tire-sizing.html

Tubes; if he needs Presta valves: http://www.amazon.com/Sunlite-Thorn-Resistant-Bicycle-Valve/dp/B000AO5K2E/ref=wl_it_dp_o_pd_nS_nC?ie=UTF8&colid=13X4M4RTA6L5I&coliid=I1IS4SIJPDT2H6
and for Schrader valves: http://www.amazon.com/Sunlite-Thorn-Resistant-SCHRADER-Valve/dp/B000AO9PY8/ref=pd_sim_sg_2

these tubes are HEAVY, but are more resistant to punctures.

no change of tube size for liners.
Nigel
Reply
#5
Thank you everyone, and especially Nigel,
That is very helpful information.
We will try what you recommend, and I will have my son research the proper way to install a tube so that it seats correctly.
~Diane
Reply
#6
Also note that an incorrectly installed inner tube will have a pinch flat really fast. So do take some time to do it correctly. I first install one side of the tyre, then put a bit of air into the tube, just so it is round-ish. Then I put the valve into the valve hole and push the tube into the tyre, working away from the valve on both sides - otherwise I tend to move the tube inside the tyre and the valve will no longer poke out radially from the rim and there would be quite some stress on the valve / tube interface.
Then, starting at the valve again, I push the second side of the tyre into the rim. Starting at the valve is sometimes really necessary when you have narrow rims, plus it makes it easier to get the tube seated correctly inside the tyre (see comment on the valve above...), again, work away from the valve in both directions. Sometimes I need a tyre lever to force the last bit of the tyre onto the rim, but that is bad style and prone to errors, it is so easy to pinch the tube, and then you have to start it all over again... yes, I know that from experience - I was under time pressure - and no, after I broke the tube when mounting the tyre I did not make it in time.
Then, inflate tyre a bit and push the tyre on the rim to both sides, kneading it a bit, all the way around, so that it seats properly. Then, inflate to final pressure.
I ride without liners, but I use tyres that are a bit puncture resistant. I had... three or four flats in the last years. One because the valve was leaking, the others were with nasty road debris, 1cm long glass or metal pieces. One was because I rode with a worn tyre on my beater and the tube was bulging out of a hole... oops. I have latex inner tubes on my road bike that are a bit more puncture resistant than the light butyl (normal) tubes. What I want to say is that there are some flats that cannot be avoided using liners. The ones with the road debris could, the others not so much.

What kind of flats does he get? Does he run the correct tyre pressure? Are they on the inside or the outside of the tube? Is the rim tape still ok, or is it cracked at some place? Are they always in one spot? Search the tube very carefully for thorns or glass when you have a flat. If the cause is not removed, the next tube will be flat soon.

Thy tyres Nigel recommended look like a good deal, very suitable for road and dirt roads / forest "roads" (at least in my part of the world).
Reply
#7
Joe's method is but one of the many ways that work well; another is described in this thread:
http://forums.bicycletutor.com/thread-5154.html
Nigel
Reply
#8
Nigel, When I looked at the tube you recommended, it says 700c, but also 27" (not 28", which is what we need). Will it really fit?
Our tires also say 42-622.
Also, to clarify, my son says the tube pokes out from under the tire, and then he lets air out, and it goes back into place. He thinks I just haven't bought the right size. (which is why I am really trying to find the exactly right size to buy!) Also, I had him read the detailed info re proper technique, and he will check the rim for possible rough spots, etc.
Thanks again
Reply
#9
(08-27-2013, 07:33 PM)Diane Wrote:  Nigel, When I looked at the tube you recommended, it says 700c, but also 27" (not 28", which is what we need). Will it really fit?
Our tires also say 42-622.
Also, to clarify, my son says the tube pokes out from under the tire, and then he lets air out, and it goes back into place. He thinks I just haven't bought the right size. (which is why I am really trying to find the exactly right size to buy!) Also, I had him read the detailed info re proper technique, and he will check the rim for possible rough spots, etc.
Thanks again

It will fit.

The tube size has nothing to do with: "..the tube pokes out from under the tire,...". The tire is not seated properly on the rim, which can be caused by method, a problem with the rim, a problem with the tire, or a combination.

With no tube at all, the tire should sit fairly snug on the rim, and require a bit of effort to remove once installed with no tube. If the tire comes off easily with no tube, there is a problem that needs to be addressed first.
Nigel
Reply
#10
Sizing can be confusing. The new 29" bikes have xx-622 tyres that would theoretically fit on your rim, which is referred to as 28". Look at
http://sheldonbrown.com/tire-sizing.html
there is a list with all common and some arcane sizes, split by use.
What kind of bike does your son have? Are there any markings on the rim of the wheels? There should be a sticker on it with size information.
Reply
#11
(08-28-2013, 05:59 AM)Joe_W Wrote:  Sizing can be confusing. The new 29" bikes have xx-622 tyres that would theoretically fit on your rim, which is referred to as 28". Look at
http://sheldonbrown.com/tire-sizing.html
there is a list with all common and some arcane sizes, split by use.
What kind of bike does your son have? Are there any markings on the rim of the wheels? There should be a sticker on it with size information.

Thank you Joe. the sheldonbrown site is certainly interesting, and detailed!
The rim says:
Safety Line
Alu 6061-T6
Weinmann
700CX28C/38C
ETRTO 622X19

This is a very tall/large bike, btw. Purchased for my tall husband.
I ordered the tubes Nigel recommended, and will post after they arrive, and we see how they fit.
~Diane
Reply
#12
700C and 622 is "regular" 28 inch wheels by today's standard, used on racing and touring bikes (and others). Tyre sizes are confusing on several points; there are lots of old bikes still in daily use, and there are numerous rim sizes which still is common in Holland and UK, but hardly ever seen in US (happens now and then though). This is one way it makes the situation complicated. 42-622 is luckily a standard size (ETRTO) wich cannot be confused (I almost dare bet on it) and available from all makers and all kinds of different styles. In real life tires vary quite a bit from maker to maker too, especially Asian brands can seem a bit off mark some times (Shin-Shen f.ex.). Tires should in theory be made to millimeter accuracy with the ETRTO standard but they are some times not. Most confusing is the sizing in inches, 26" is very often not 26", and neither is 28" !
Reply


Possibly Related Threads...
Thread Author Replies Views Last Post
  Please help, Tube sizing problem for my Univega Sport mrb1974 1 3,099 08-27-2014, 11:03 PM
Last Post: DaveM
  Tube sizing help for 27" wheels retro-roadie 2 3,534 06-29-2014, 11:17 PM
Last Post: retro-roadie
  Bike tube sizing drlreed 1 2,810 04-05-2014, 02:42 PM
Last Post: DaveM
  Tube/Tire Sizing Help Budtooz22 2 4,054 10-29-2013, 07:32 PM
Last Post: Budtooz22
  Tube fit solution - and some tube replacement questions jdohe 6 8,052 10-29-2009, 06:45 AM
Last Post: Joe_W

Forum Jump:



ISSN 1918-3445 © Copyright 2007-2010 Bicycle Tutor / Privacy Policy / Created by Alex Ramon

feed