Repeated rear punctures!

slimboyjim

Hi all,

I seem to suffer an annoyingly high amount of rear punctures and I was wondering if anyone could help or offer advice? For information:
- I have a DT Swiss 5.1 rear on a FS bike with Continental Speed Kings (2.2) and tend towards red trail's. I weigh 11 stone, plus maybe an extra stone (?) with water and kit. I tend to get the punctures riding rough ground at speed (i.e. downhill - I'm not so quick uphill :roll: ).
- I tend to get through 1 or 2 tubes every 20 miles which is a pain with how hard it is to take the tyres off the 5.1's! This is once per serious ride...
- I've checked my rear tyre and there are no obvious thorns sticking through.
- I've tried various 'quality' brands of inner tube and they all seem to puncture the same.

So:
1) Is this a reasonable amount of tubes to be getting through?
2) With the amount of punctures I am assuming this must be technique related - I didn't think I was hanging off the back of my bike that much but is it possible to 'overload' the rear and how easy is it (relatively speaking)? I'm booked into a skills course soon anyway...
3) Can anyone think of any other checks I've missed or have alternative explainations? I don't think it's a spoke poking through as the tube will last for ages if I am riding easier terrain.
4) What can I do to minimise the risk of future punctures (low pressure? stronger tyre? etc.)? I cannot really afford to go tubeless unless it is 'ghetto' style.
5) Would DH/self-healing tubes be better? Can anyone make any recommendations - I need it to fit a 2.2 tyre and be presta valved...

Thanks for your help in advance - I'd be bit happy if I was particularly heavy or riding really tough (black) terrain but this is just confusing me!


James

rhann

what sort of puncture, does it look like a snakebite/ where is the puncture? have you checked the inside of the tyre, the rim?

rhann

tyre pressure?

ride_whenever

what sort of punctures? Pinch or thorns?

If just pinches then run a bit more pressure...

if thorns as well then you're best bet is to go tubeless, easy with dt rims, they do a conversion kit.

ploeb

I dont know about Speed Kings, but I had Conti Mountain Kings 2.2 for a while and I got punctures almost everytime I went for a ride. Even on road sometimes. I had three punctures on one lap at Afan Forest once. With Panaracers for example I have almost no punctures, so I conclude the Mountain Kings are too thin for me and Speed Kings may be similar.

Soul Boy

Something I do is line up the decals on my tyres with either the valve hole or decals on my rims. Sounds a little anal, but when I get a puncture I can find the hole in the inner tube and match it up to a section of tyre. It makes finding thorns etc protruding into the tire a hell of a lot easier (and I've had tiny spikes stuck though my tire).

You've already checked your rim and made sure your rim tape is in good order.

Lastly as mentioned, check pressures, too low and you're likely to pinch the tube if you hit a rock or root heavily.

Oh, good luck.

ride_whenever

but with punctures there'll normally be a little white area where the talc or whatever comes out of the tube on the inside of the tyre.

Soul Boy

OK, so I'm just a tart.. 8)

ride_whenever

That's it, admit it, come to the tart side...

fitch28

i find it helps to run a bit of loo roll round the inside of the tyre just to check that there is definitely nothing there. tissue should snag if there is anything to worry about.

ride_whenever

Or just put on a new tyre as well.


Also check your rim tape and vavle hole...

robertpb

Have you checked for swarf, had quite a few bits of it in my rims when I first bought my bike.

Belv

Stuff rotating weight - i've fitted tyre liners.

slimboyjim

Cheers for the help guys!

Rhann - The punctures tend to be very small pin-prick type holes. I cannot remember whether they are on the inside or out but still have the tubes - I'll check although work will prevent me doing this for a day or two... I'm not sure about tyre pressures specifically as I only have a mini-pump at the moment. I have always felt the rear was pumped up relatively high though...

***Just to check my knowledge, as I understand it there are 2 types of punture - pinch and thorn. Pinch is where the inner tube is pinched betwen the tyre and the rim, whilst thorn is a pin prick to the innertube. Is there a good way to check which type it is (sorry - I know this is probably somewhere on the forum already)?***

Ride_whenever - I am tempted by the conversion kit, only it's £40+ last time I looked and I'm a bit skint. Saying that I'll be buying a new winter tyre soon so will get one that's tubeless compatible just in case... At a guess I'd say the punctures are probably pinch as I only seem to get them when tackling rocks/kerbs (I know - the kerbs are just asking for trouble :oops: ).

Ploeb - I'd imagine the Race Kings are much less protective than your MK's! I know they are much more flexible than my previous tyres so there's a good chance they are deforming easily and offering very little pinch puncture protection. I'll be trying a new rear tyre soon with the change of weather so I'll see (perhaps a rubber queen to match the front, but I'm not decided yet)...

Soulboy - I too am a bike tart

Robertpb - Good shout about the swarf - I'll have a good clean out next time the tyre is off.
(Thanks all for the suggestions about the rim - I'll check there's no nicks on it at the same time...)


James

xtreem

If you're getting pinchflats, then:
- Run with higher pressure
- Put fatter inner tube (for 2.2"-2.5", not for 1.9"-2.125" tires)
- Pick better lines, and work with your legs.

slimboyjim

- I'll try the higher pressure.

- My current tubes are for 1.75"-2.5".

- I have a skills course booked midway through next month - hopefully this will get rid of some of my bad habits!

fitch28

pinch punture usually results in 2 small holes rather than one

slimboyjim

Thanks Fitch - I'll look over my punctured inner tubes tomorrow to check them out...

bomberesque

I had the same problem and (coincidentally) the same rims

I got myself some beer, some wheelmilk, a couple of Schwalbe 20" innertubes, a knife and a track pump and I rocked over to this site. an hour or so later I had 2 ghetto tubeless'd wheels. One year later I am still to have my next puncture.

KonaKurt

Slim, where exactly are you riding to get these flats?
Sometimes, it is easy to miss something obvious, like a favorate frequent route or trail being littered with sharp flint or dead (but still thorny) bramblebush. Check carefully inside the rim and tyre next time, to see if you have anything sharp left in there. If not, it could be as simple as bad luck hitting sharp rock. This happened to me several times last autumn when I just put my punctures down to bad luck.

There seems to be ALOT of broken glasss bits around these days, both off and on trails.
Vandals!

KK.

xtreem

[b]slimboyjim[/b] wrote:

- My current tubes are for 1.75"-2.5".

Well, they maybe can fit 2.5" tires, but their wall thickness is not very big.
What's your inner tube, name or link?

Btw, I run 0.9mm thick tube at the front and 1.2mm at the rear.
So it does helped reduce pinchflats.

slimboyjim

Xtreem - My current inners are Continental, but I've not had good experiences with Bontrager or Nutrack either. They are all just standard innertubes (not DH specific, etc.) and I could not tell you the wall thickness.

These are the Conti's:
http://www.chainreactioncycles.com/Mode ... elID=18901

Do you have any suggestions for innertubes to try? As previously mentioned my rear requires a Presta valve...

KonaKurt - Tend to ride around Cannock Chase with the odd trip to Wales thrown in every other month. Punctures seem to be consistent with riding rough sections of rock...

Bomberesque - Thanks for the Ghetto link - I'm thinking it's got to be worth a try at the moment. I'm bored changing tyres when I want to be riding!

Thanks all!


James

xtreem

Could not find the wall thickness of your tubes, but here's what I recomend on the rear only:
Maxxis Freeride Tube
It's what I have, and it will help reduce pinchflats a bit.

Btw, have you checked the other inner tubes if they have two holes?

Northwind

Soul Boy wrote:

Something I do is line up the decals on my tyres with either the valve hole or decals on my rims. Sounds a little anal, but when I get a puncture I can find the hole in the inner tube and match it up to a section of tyre.

This is good advice... Simple but really effective, means you can watch for repeat punctures. Looks better too

fitch28

hi, was flicking through a wee mtb book today and noticed a bit saying that if you carry too much of your weight to the rear of the bike it can result in a lot of rear punctures.

just a thought....