Bicycle TutorBicycle Tutor

Show off your bike!

Related video tutorials:
Low Pressure 27x1 1/4 tires
#1
I'd like to buy some new tires for my road bike. The road bike is a 1981 Free Spirit Pinnacle and the bike has steel rims that cannot accept pressures over 75 PSI without blowing out. My LBS has been giving me tires that require 90 PSI. When I pump them up to near 90 PSI (85 PSI) they blowout. When I under-inflate them to about 60 to 65 PSI, they have problems and get pinch flats.

My front tire was replaced when I bought the bike because the first time I rode the bike it got a puncture (the bike had original tubes and this happened in 2011) and the LBS replaced the front tire and the tube in the rear tire. The front tire only requires 70 PSI.

Is there any good cheap tires in the 27x1 1/4 size that only require 70 PSI? The only ones I've found are 90 PSI.

I don't have the money to buy replacement rims or wheels. So I'm going to have to buy a new tire and tube. The existing tire not only blew off when I pumped it up to 90 PSI (this is when I found out it will not accept 90 PSI) but found out it is pretty much dry rotted. The current tube also has a puncture in it from a pinch flat.

Any help is appreciated, thanks!
Reply
#2
A couple things;

Get these tubes, or similar thorn resistant tubes - they will eliminate the possibility of pinch flats:
http://www.amazon.com/Avenir-Thorn-Resistant-Schrader-Valve-700x35-45/dp/B00165SA1O/
If you are near, and stop over I will give you two that came off our tandem when I replaced the wheels with ones that require Presta valves. I'll even assist you with mounting them. PM me if you are close enough.

These tires will fit your bike, and will be fine at 70 psi with the thorn resistant tubes list above:
http://www.amazon.com/Kenda-Street-Tire-Wire-Wall/dp/B000IQCJCS/
they do not require 90/92 psi, that is their maximum rated pressure.
Nigel
Reply
#3
Thank You! Sadly, I live in Missouri. But thanks!
Reply
#4
Thank you for your post!

I have a 1983 Miyata 110 with steel rims and 27 x 1 1/4 tires. I experienced my first blowout after a bike maintenance workshop at my LBS where the instructor told us to inflate our tires to the maximum PSI (90 PSI, in my case) to avoid pinch flats. I had never inflated them that much before and had never experienced pinch flats, but I trusted the instructor. The rear tire blew out after riding just a few blocks. So frustrating!

After that, I bought a Kenda K35 tire 27x 1 1/4 wire bead 90 PSI, which I inflate to around 75 PSI. After the blowout, I read online that about 75 PSI is good for these rims and going above can cause blowouts. Ugh!

The problem I have now is that a bulge forms on the tire when I inflate it. There is a slightly worn spot about the size of dime on the inside where the bulge forms (see photos). I couldn't find any debris in the tire and have no idea what caused the worn spot. Have you ever seen this?

I need to get a new tire, but am reluctant to buy another Kenda K35. What did you buy?

[attachment=5393]
[attachment=5394]
[attachment=5395]
[attachment=5396]
Reply
#5
(10-13-2014, 10:11 AM)miyata Wrote:  Thank you for your post!

I have a 1983 Miyata 110 with steel rims and 27 x 1 1/4 tires. I experienced my first blowout after a bike maintenance workshop at my LBS where the instructor told us to inflate our tires to the maximum PSI (90 PSI, in my case) to avoid pinch flats. I had never inflated them that much before and had never experienced pinch flats, but I trusted the instructor. The rear tire blew out after riding just a few blocks. So frustrating!

After that, I bought a Kenda K35 tire 27x 1 1/4 wire bead 90 PSI, which I inflate to around 75 PSI. After the blowout, I read online that about 75 PSI is good for these rims and going above can cause blowouts. Ugh!

The problem I have now is that a bulge forms on the tire when I inflate it. There is a slightly worn spot about the size of dime on the inside where the bulge forms (see photos). I couldn't find any debris in the tire and have no idea what caused the worn spot. Have you ever seen this?

I need to get a new tire, but am reluctant to buy another Kenda K35. What did you buy?
I think the bulge is a tire defect. Manufacturing defect?

They have some good, cheap 27x1 1/4 tires. I haven't got around to fixing that old bike so I haven't tried any... just stay away from the Cheng Shin tires - I went through three of those in a matter of months.

Also, most 27x1 1/4 tires require 90 PSI to avoid pinch flats - inflating them to 75 PSI (so they don't blow off the rims without hook beads) will almost always give you a pinch flat (in my experience.) You may need a new rim to suit the new high pressure tires.

Below is a link to a bunch of good 27" tires - including 27x1 1/4 and 27x1 1/8 tires.

http://sheldonbrown.com/harris/tires/630.html
-Garrett, Boonville, MO
Reply
#6
As I noted on the OP's other post that is not a manufacturing defect. The fact that it was only noted after a pinch flat (not noted in this post) means that whatever caused the flat also ruptured the cords. The tire must be replaced.

As for tires/inflation, it is indeed difficult to mount higher pressure tires securely on steel rims, but it is possible. It's common to mount tires/tubes incorrectly so that they blow off, even on hook bead rims. My recommendation would be to inflate to a good quality high pressure tire to 80 psi. A properly mounted tire should not blow off under that pressure, and unless the OP weighs over 200 lbs or is carrying heavy weight over the rear tire there should not be a pinch flat problem.

Before the mid 70's high pressure tires were relatively rare, and 27 x 1 1/4 steel rims were common. I routinely inflated my 27 1 1/4 Michelin's to 80-85 psi on steel Ridiga rims. If the OP is heavier 27x 1 3/8 might be an option as long as inflation limit is adequate.
Reply
#7
Thanks, everyone.

Just for clarification, I did not find any holes in the tube that looked like a pinch flat.

Could the holes be too small to see?

Could a pinch flat create a slow leak that causes the bike to go flat overnight (rather than much faster)?
Reply
#8
There is no rule about how big a hole will be created by an impact, so yes, the hole could be quite small, and not necessarily the slit/snakebite typical of a pinch flat. The fact that the tire went flat and that you only noticed the tire problem afterward points strongly to the same thing causing both problems. I have seen such damage many times before and experienced it once myself on tour when I did not see a small rock in the road.
Reply


Possibly Related Threads...
Thread Author Replies Views Last Post
  27x1 1/4 to 700c Conversion garrett01 18 36,541 01-30-2015, 02:51 AM
Last Post: cask04
  Tube deflates at rest but holds pressure while riding nutnelson 4 2,812 07-07-2013, 02:44 AM
Last Post: 1FJEF
  Tire Pressure Question stevetopbarnarna 3 5,061 03-26-2011, 06:48 PM
Last Post: nameused
  Tire pressure idea I came up with Larry H 6 5,350 10-03-2010, 03:52 AM
Last Post: 009jim
  Newbie w/air pressure question Bikeshrink 7 5,856 08-05-2010, 10:44 PM
Last Post: Bikeshrink
  Tire pressure question Caroline212 2 3,499 06-26-2009, 12:20 AM
Last Post: Caroline212
  Bike vs. Car Tire Pressure canadianliberal 4 9,044 08-24-2008, 12:35 AM
Last Post: canadianliberal

Forum Jump:



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

feed