feh, bicycle tire tubes, disc brakes, ugh

[lucydad]

All,

So I have a nice Cannondale bicycle I ride several times a week.  Turned up with flat front tire on Thursday.  Messed with it, won't hold air, so pulled front wheel and took to bicycle shop.  Sure, quick fix, new tube, old valve separated.  Get it home, and ride maybe 8 miles.  Bike sits overnight, check Friday morning:  flat.  Back to bike shop, they replace tube again.  Get up early Saturday morning for a ride:  flat again.

Repeat to bike shop again:  they put in a different brand tube.  We will see.  But now I can't adjust wheel so front disc brake does not drag.  Not severe, but not a free wheel.  Don't have a bike rack or truck.  So, do I risk riding the bike into the shop (about 8 miles)?  Will tube number 3 hold air?  Will the ride with a slightly dragging brake harm the disc brake?

Feh.  Crappy morning.

[Triple Jim]

The disk brakes on my mountain bike have some fairly simple adjustments for centering on the disk, and play before pad contact.  Maybe  you can find the instruction manual for your caliper(s) on the manufacturer's web site.

If the brake isn't dragging so much as to make pedaling difficult, I doubt if you risk causing damage by riding it.  You could ride half a mile or a mile, stop, and cautiously feel the disk to see how hot it is.  If it doesn't make spit sizzle, it's not very hot.  But maybe it would be wise to call your shop and ask the same question.  At least if they say to ride it and something goes wrong, they may have incentive to fix the damage at no cost to you.

I don't mean to be a smartass, but you should probably practice changing and patching your tubes yourself.  Many times I've been on trails way out in the middle of nowhere and had a flat.  Being able to take out a patch kit, patch the tube, and continue riding is a pretty important skill.  Even if it's just to save a trip to the shop, it's worth learning.  It's only a 15 minute job.

[PJPR01]

Check the rim liner covering the spokes or look for a burr there where the leak is...most likely the culprit.

[Guido Valvole]

+1 on Jim's suggestion to practice patching tubes. It's not hard, bicycle tires are **so** much easier to deal with than motorcycle tires. I learned out of necessity when I was a kid, and back then there were no such things as plastic tire levers. Just be really careful with a screwdriver. Now, plastic levers, patch kit (and other tools) and spare tubes in the bag for every ride.

I can't help you with discs, rim brakes only here. They work well enough and are simple. Your tires could be a major part of the problem if their tread pattern means thin spots, common with blocky mountain bike tires. Since switching to Schwalbe Marathons I've only had a problem with tube failure. One more hint -- patches can fix tires, too. I've had to do that twice. First was a blowout when I hit glass. Mountain bike tire. Mcgyvered it back together with a couple of patches & glue and more to fix the tube and made it home. Second was a Marathon XR that picked up what looked like a 1/8-inch machine screw about 3 inches long. Patched the inside of the tire, had to toss the tube as it was skewered, and made it home. And kept riding on the tire for a couple of years. (cheap Guzzi-guy content).

Now watch me get two flats next ride...
cr

[tazio]

Loosen and tighten quick release. Spin tire. Repeat.
Good to carry spare and co2.
Practice flat repair at home.
Ck. for burrs as stated and make sure rim tape is wide enough..
Bicycles are the cats pajamas. Give mountain biking a whirl!

[lucydad]

No patching these tubes:  complete disintegration-separation where small valve connects.  Shop owner thinks they have a bad batch (China). He said: impossible to patch.  Once I spent the $17 for a new tube and repair, why mess with it myself?  Checked the rim:  no problems.  Thanks for info on the disc and drag-heat.   Looked up how to adjust the disc gap, its not so simple.  Decision is to see if it is flat tomorrow morning.   If not, I will ride it to dealer and let them adjust the drag.  Then I will ride on.

Also have a stomach bug, so not very energetic right now.

Thanks. 

[janusz]

No patching these tubes:  complete disintegration-separation where small valve connects.  Shop owner thinks they have a bad batch (China). He said: impossible to patch.  Once I spent the $17 for a new tube and repair, why mess with it myself?  Checked the rim:  no problems.  Thanks for info on the disc and drag-heat.   Looked up how to adjust the disc gap, its not so simple.  Decision is to see if it is flat tomorrow morning.   If not, I will ride it to dealer and let them adjust the drag.  Then I will ride on.

Also have a stomach bug, so not very energetic right now.

Thanks.

The reason the separation happened was the nut on the valve was tightened too much to the rim and prevented tube to move as tire moved on the rim. To prevent this you should not tighten that nut too much, better yet just don't use it at all. I personally don't take my bikes to the lbs for any maintenance (see exception list at the bottom), it is very easy to do it myself and I hate to see some high school kid practicing on my bikes. Changing the tube is very easy and most important if you do it on your own you will be able to identify what cause the tube puncher in the first place. When mounting tire back on the rim it is good idea to smear the side walls of the tire with 50/50 mix of dishwasher liquid and water. It will help to put tire on the rim and also it will prevent tire movement on a rim when dried. Another solution is to go tubeless, but it may be expensive proposition if you decide to get a new tubeless wheel set. A cheap option would be to use http://www.notubes.com/Stans-Tubeless-Kits-C12.aspx but if you have a flat it will be messy to fix.

The disk brakes drag is caused by couple of things:
- you don't install the wheel properly
- the break drums/calipers are dirty and need good clean up.

I don't know what brand of brakes you have but all of them are very easy to adjust. Just to put this in the perspective, I will never do any work on my MG, but on my bikes (MTB and road) I can do any work with exception:
- will NOT service my front/rear suspension on my MTB
- will NOT mess with Di2 settings on my road bike.

For the record, my BMC with tubed tires I've never got flat yet. On my Cannondale MTB with tubeless tires (use Stan sealant) I had to call my wife once to pick me up because I didn't replace sealant after 12 months of use and didn't carry any tools but the cell phone :)

BTW, it is not about $17.00, it is about peace of mind :)

[lucydad]

janusz,

Do you look forward and back at the same time?  Anyway, thanks for your comments.  Tire is still holding air, sitting in garage.  I loosened lock nut on valve. As far as the brake drag, three times I got it nice and free.  Last time:  no luck.  No idea why.  Hours and frustration spent take a toll.  Likely I will ride the bike to the shop Monday and leave it, or let them adjust brake on spot.  Lots of dirty wet-mud riding here with endless storms, construction area, etc.  Filthy bike is the norm, but I do wash it.  Great dealer, no charge, not their fault the tubes were faulty manufacture.

I am a lousy mechanic, that is who I am. 

Same  bifocal issues focusing on small black parts as with motorcycles:  eyes go wobbly.

ride safe!

And yeah I used to have a mountain bike when we lived in Ken Caryl, CO.  Also rode in in Tunisia, North Africa.  Been on some interesting roads in both mountains and deserts.