Sloooooow Puncture.

ChrisMidsUK

It looks like I got my first puncture and it's quite a slow one, can take at least 30/60 minutes for the rear tyre to turn ''squidgy' before having to pump it up.

Bike - Stumpy comp 09
Rear Tyre: S-Works The Captain, 26x2.0 inch, 120 TPI, Kevlar bead, Dual compound, Tubeless ready
Rims: Custom DT Swiss X420SL, 24mm with eyelets, 28/32 hole
Tubes: Specialized Ultralight 26x2.0 inch, Presta

In truth, I should have took a look before going on a ride as I noticed the pressure was 'slightly down' before setting off, which made me suspicious. But it seemed nice and solid after pumping it back up and not going straight back down so all seemed well and off I went.

Was out for about 2 hours or so off road and had to stop 3 times to pump it up, also had to give some of the rougher stuff a miss due to the problem.

I haven't took the tyre off to have a look yet as I was tired after the ride, so have just cleaned/lubed for today and will look tomorrow morning.
But i did inspect the rear tyre thoroughly mid-ride and couldn't see any signs of piercing or anything else.

Just supposing I remove the tyre tomorrow, submerge in a bucket of water and find no holes? I'm wondering if the presta valve could be leaking air slowly.
The reason I say that is because I noticed the small ring around the valve, next to the rim was a little loose, as I tightened it, water started coming out under the ring, with a 'bubbling' effect too.

I have been doing some small jumps (well trying but failing to keep the front wheel up actually :oops: ) of about 2 or 3 feet high max, bunny hops and grabbing some air where I can, but certainly nothing on a major scale. I'm not going to attempt downhill big ass jumps, that's for sure but I also realise these bike components may not be as strong as they appear. I'm wondering if I may have damaged the valves.

Can you guys (and girls) advise me if I should steer clear of attempting (small) jumps with my kinda XC setup? Presta valves don't seem particularly strong and I wish the tubes had Shrader valves but get the impression those tubes might weigh 'slightly' more?

I was a little surprised when buying the bike that presta were fitted, is this normal XC setup and are the stronger Shrader valves used more on the dirt jump type bikes for obvious reasons, and perhaps not considered essential for bikes that won't be attempting 10 feet drops?

I'm unsure whether I should stick with presta valves for the future, and don't know at this point if shrader will fit through my rims?

One last question if I may, some guys I met recently who all seemed sound as a pound were advising me on a few things, one of them seemed to really know his stuff and was telling me my X-7 shifters are notorious for problems, he described a few problems I might notice and he was spot on, once again today, I had a problem where the left side shifter was stuck on number 3, had to wiggle the black plastic lever so that I could move down the the middle ring, annoying as I only had the bike a month.

But this guy did say I'd be better off to upgrage to X-9 or other better shifters once the warranty has run out, he also said bike stores might tell me it's the cables causing the problem but this ain't true, every guy he knows has had the problems with X-7, but not with X-9, anyone agree with that?

Thanks in advance.

nonnac85

I was fixing my mums bike the other week - she thought she had a slow puncture but it turned out to be the valve core was slightly loose. might be worth checking.

ChrisMidsUK

nonnac85 wrote:

I was fixing my mums bike the other week - she thought she had a slow puncture but it turned out to be the valve core was slightly loose. might be worth checking.

Thanks, I'll take a look today and see if it is the valve or a tiny hole, just got this hunch the vavle might be damaged.

I could do with knowing whether most other riders use presta valves for XC riding?

I know my tyres are tubeless ready, not sure how easy that is to swtich to and if it's worth it?

And anyone else had bad experiences with X-7 shifters?

nonnac85

I ride loads of different styles / trails. Have always used schraeder valves. I dont really think there is a weight penalty because you can get light and heavy inner tubes with either type of valve.
Thank god i do use schraeder - i was out recently, 15miles from home and got a puncture. Fixed it and went to blow it up but my pump broke. Went to nearest village and a lady lent me her car pump. This would not have worked with presta!

BorisSpencer

Presta valve stems can easily be snapped off when using a mini pump. If possible use a pump with a flexible hose.

Ditch Witch

I hate presta valves, despite having them on my tyres.

ChrisMidsUK

BorisSpencer wrote:

Presta valve stems can easily be snapped off when using a mini pump. If possible use a pump with a flexible hose.

Yes I have one of those and can see what you mean, I've also tried using the other type of mini pump and note the valve moving about while pumping, flexi hose is the way to go.

Well, I took the tyre off today, turned out it was a puncture after all which took me by surprise, it really was sloooower than slooooow with regards the air coming out. The hole was so tiny, made by the tiniest of thorns I've ever seen.

Believe it or not, this was the first time I've ever mended a puncture and it all went fairly smoothly, wasn't looking forward to it as it was the back wheel but glad I did it as I feel confident I can fix it roadside now, just need to carry a bowl of water with me if no spare tubes.
Can't beleive I've still not bought any spares to carry in a month of having the bike, must go to bike store tomorrow! :idea:

Northwind

[quote="nonnac85" Went to nearest village and a lady lent me her car pump. This would not have worked with presta![/quote]

You can get adaptors, they're tiny so just throw one into your camelbak.

I don't like prestas... The talk of a weight penalty for schraders doesn't hold up, there's almost no difference between equivalent tubes (see- bonty xxlite, for instance), but since presta are seen as the light option, if a company only wants to make one light tube they make it a presta. It doesn't seem to have any impact on the strength of a well designed rim either, look at mavic, they drill their rims for scrader and supply a spacer.

But, presta is what I'm stuck with now

ChrisMidsUK

Thanks for your help NW. Think I will look to buy tubes with Schrader's providing they fit my rims.

allthegearnoidea

crhis, did you check the tyre as well?? (guessing you did) otherwise you'll possibly end up witht he same issue on the repaired section?

i normally mark the tyre witht he yellow waxy crayon where the valve is before taking it off, makes it easier to find then when looking for thorns etc!

you may find that your rims have little 'donuts' in them on the valve hole to make them able to accept either schrader or presta, if not then you 'can' carefully drill out the hole to do so, just make sure you clean the sharp edges off the hole after (i think deburring is the techy name for it??), 8mm drill bit i think it is??

BorisSpencer

When you re-fit your tyre, line the logo up with the valve hole, it's not just for show, it's so you know where in the tyre to look once you've found the hole in the tube.

ChrisMidsUK

allthegearnoidea wrote:

crhis, did you check the tyre as well?? (guessing you did) otherwise you'll possibly end up witht he same issue on the repaired section?

Yep, pulled that little sucker out with tweezers.

allthegearnoidea wrote:

you may find that your rims have little 'donuts' in them on the valve hole to make them able to accept either schrader or presta, if not then you 'can' carefully drill out the hole to do so, just make sure you clean the sharp edges off the hole after (i think deburring is the techy name for it??), 8mm drill bit i think it is??

Yes, I have silver 'donuts' that screw to the rim, holding the presta in place, I'm guessing by the size of the hole, Schrader would fit in their snugly.

allthegearnoidea wrote:

i normally mark the tyre witht he yellow waxy crayon where the valve is before taking it off, makes it easier to find then when looking for thorns etc!

BorisSpencer wrote:

When you re-fit your tyre, line the logo up with the valve hole, it's not just for show, it's so you know where in the tyre to look once you've found the hole in the tube.

Some good tips there fellas, thanks.

Stephen-Hawking

An dif it's the rear tyre make sure you put the gears into the smallest (outer) cog. Makes it easier getting the wheel in and out.

ChrisMidsUK

Just as an update.

Had quite a strange situation after patching up the hole, the very next day, air had once again come out but not as much as before, but enough to notice.

I used a (cough) Halfords puncture kit and to be honest, the patches don't seem that good although I did forget to clean the surface of the tube first. (doh!)
So I whipped the tube back out next morning and put back under water after pumping the tube up, enough to create some decent pressure.

Nothing, not a jot, no air bubbles coming from anywhere, and I did take care to hold the valve area and patched up area under for longer.

So I just wonder if anyone else has expereienced that? Leaking air but no signs at all of a hole and faulty valve? Wierd!

Finally bought my first spare tubes, normally £4 each for these Spesh ones but I haggled 10 for £30 so that should last me until the end of next week.