Mid corner puncture - why?

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Mid corner puncture - why?

Postby sb944 » Thu Feb 14, 2013 8:59 am

A little background, I'm no lightweight at 95kg + backpack, on a decent carbon road bike. I've done about 4 bunch rides in Homebush recently, the "quick" ones, but graded 1-6, I'm starting in 6. I seem to always play catchup after every corner, which is OK at this level, but in a higher bunch will become impossible, and annoying for others I'm sure. So I've been pushing my corners harder and harder, and today was feeling like I was keeping up on around 1/2 of the corners, but only when I really focus hard on what I'm doing.

I was focusing hard on a fast corner and keeping up with everyone. I'd say I was keeping up this time, but I don't think I was going faster than the others, when I felt a little slide mid-corner like I was pushing it too hard. It didn't cause me to fall, but as I slowed and started to straighten a little, I slid again, and then it was obvious I had a flat. I managed to get out of the bunch without any incidents, which I'm very pleased about.

These are relatively new Continental GP4000 tyres, and a close inspection showed no tyre issues. I'd pumped them up the night before, and hadn't noticed any problems until the incident happened.

I'm trying to work out whether I just pushed it too hard around the corner and my attempt to not crash caused the puncture, or whether I probably got the puncture somehow on or before the corner, and the sliding was obviously caused by that.

I'm hesitant as it is around corners, this is not going to help.
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by BNA » Thu Feb 14, 2013 9:17 am

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Re: Mid corner puncture - why?

Postby rogan » Thu Feb 14, 2013 9:17 am

sb944 wrote:I'm trying to work out whether I just pushed it too hard around the corner and my attempt to not crash caused the puncture, or whether I probably got the puncture somehow on or before the corner, and the sliding was obviously caused by that.

I'm hesitant as it is around corners, this is not going to help.


Based on what you have said, there is no way you pushed it too hard around the corner. There'd be blokes as big as you in the faster packs, and puncturing due to pushing it too hard through a corner is basically unheard of (rolling tubulars is a different story, but I doubt that's an issue here). The friction that holds you to the road would give well before the tube inside the tyre - ie. if you push too hard through the corner you have a slide out fall rather than a puncture. Your attempt not to crash almost certainly did not cause the puncture, unless you got a pinch puncture.

You almost certainly got the puncture before the corner, from what you have said, probably a slow leak. The fast leaks you generally know about very quickly.

It's a dangerous situation. Bad crashes can be caused by it. But if you use good tyres, check them regularly and pump them up to the recommended pressure, you would be unlucky to have this happen more often than once every 5 to 10 years.

The only way to get better at cornering is practice. The slower LACC bunches are as good a place as any to improve. It's not necessarily a question of pushing yourself through that uncomfortable feeling (although there will be days when you probably should). It's more a case of doing it so often and so much that you don't think about it, and can just concentrate on your riding.
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Re: Mid corner puncture - why?

Postby human909 » Thu Feb 14, 2013 9:19 am

THIS: I probably got the puncture somehow on or before the corner, and the sliding was obviously caused by that.

If you can't handle corners then you either are way too scared or you have very poor bike control. I suggest you practice you bike control in a safe area like a car park. Spend an hour taking slow tight turns. Set up some cones and practice. Once you can do it at low speed then at higher speeds it is EASIER (but possibly more scary).

High speed turning on a bike shouldn't be any harder than on a car. Most braking should be prior the corner, pick your line and no sudden movements.
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Re: Mid corner puncture - why?

Postby g-boaf » Thu Feb 14, 2013 9:50 am

Have you thought of anything inside the wheel that might have caused this? I had that problem once - it took a few punctures to work out why it was happening, including a sliding moment through a turn (which my l33t bike handling skillz saved)!

Otherwise, you might have picked up a slow puncture ahead of the corner. Though it my experience, the punctures always seem to end up with the pressure going down quickly.
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Re: Mid corner puncture - why?

Postby sb944 » Thu Feb 14, 2013 12:09 pm

Thanks guys, I can believe it was a slow leak, the tyres have otherwise been leak/puncture free for 1200km and never taken off, so I don't see that something got in the tyre in the last day or so.

On the cornering, I like the advice about practising while going slow. I've built up enough fitness and confidence to ride with minimal fear of situations, but I still always get nervous around low speed situations, like navigating around pedestrians on a narrow overpass, or going around tight corners on an overpass.
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Re: Mid corner puncture - why?

Postby RonK » Thu Feb 14, 2013 2:07 pm

Set up witches hats or similar to make a slalom course - an empty carpark is a good place to do this.

Practice with different spacings and gradually build up the pace.

You should eventually be able to slam through the course.

For low speed, practice with the markers close together.

Have slow race over the course - last to finish is the winner.
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Re: Mid corner puncture - why?

Postby g-boaf » Thu Feb 14, 2013 2:09 pm

sb944 wrote:Thanks guys, I can believe it was a slow leak, the tyres have otherwise been leak/puncture free for 1200km and never taken off, so I don't see that something got in the tyre in the last day or so.

Seems like a slow puncture. I've never had one of those, mine just seem to go quicky resulting in a oh *&## cursing. I've never gone off as a result of that though.

On the cornering, I like the advice about practising while going slow. I've built up enough fitness and confidence to ride with minimal fear of situations, but I still always get nervous around low speed situations, like navigating around pedestrians on a narrow overpass, or going around tight corners on an overpass.


What's your home like? Got a decent size backyard or front yard with a grassy lawn? Stick out some witches hats or plastic bottles or something and practice riding between and around those at low speeds. You'll get use to it quick. Pedestrians on the other hand are always scary to ride around because you never know quite what they are going to do, especially if they are on a wide and open area like a town square. Then start to learn how to track stand - and you'll be one of those uber-cool riders doing the track-stands... :P

Edit: Ron beat me to this.
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Re: Mid corner puncture - why?

Postby jules21 » Thu Feb 14, 2013 2:47 pm

you need to identify where the puncture was - on the tyre or rim side? how big was the puncture (i'm guessing a pin hole if it was a slow leak)

on the tyre side usually means penetration by foreign object - which you can identify by locating said object or at least a hole in the tyre.

on the rim side can mean a couple of things - a snake bite (2 small tears in the tube where it gets squashed between tyre and rim) - which results from hitting an obstacle, usually with insufficient air pressure, or a bit trickier to identify - being cut by a sharp edge of rim tape, usually the plastic variety. you may find an imperfection in the rim tape where it's been disturbed, or it could be due to just the undisturbed edge of the tape itself. fabric tape is better.
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Re: Mid corner puncture - why?

Postby warren.suen » Thu Feb 14, 2013 5:44 pm

oh a side note.. i'm in the same boat as you in terms of cornering where i can keep up easily on the straights but everyone seems to motor past me in the corners!

getting better but i think its just trust in the tyres and road and really watching what everyone else is doing in the corners
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Re: Mid corner puncture - why?

Postby Baalzamon » Thu Feb 14, 2013 6:48 pm

slow leak. You picked the puncture up before the corner. I've had this happen to me tyre going down slowly and into a corner I go and OOOOH feel it slid a bit. Looked down and sure enough flat.
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Re: Mid corner puncture - why?

Postby sb944 » Fri Feb 15, 2013 8:40 am

I'm going through a strange couple of days. After the puncture I turned the garmin on, but didn't record the ride. Further on, I noticed unusually big float in my new left shoe, and instantly knew the bolts must have come loose. I pulled over and tightened all the bolts, which were loose, not sure if this was to blame for anything, probably somewhat caused by me jolting around during the mid corner incident. I then decided on the way home to focus more on balance than speed/segments. I stopped at a couple of lights without unclipping, something I've been scared to do, and was practicing riding no hands, which I can do on the cheap bike, but always been too scared on this one. I nearly had it after a few attempts, but it almost always falls to the right, which might be a sign of some huge balance issue.

I rode in today and felt a real lack of confidence around corners, I mean before getting to them. Then at the bottom of a hill, I have to get across a road, and usually like to do it quick to avoid cars that might come quickly around the blind corner, I missed my clipin, hit the carbon sole on the pedal and fell back onto the seat. Now my seat was tilted forward. I stopped unscrewed it, re-tilted it back, but it's still not back where it was, I haven't looked at it yet, hope I didn't break something. I'd also noticed the cadence wasn't working, so I slid the crank magnet up a little. When I got back on the bike (or me) felt sluggish. I pulled over for a bit, looked at everything, and apart from the wheels looking a little out of true, there is no rubbing problems anywhere. I then got a 14 seconds PB on the next hill, so there is nothing wrong with the bike performance, I think it's in my mind.

I think I am getting an aftershock of this incident. I now fear turning at any decent speed, and feel like I don't have control of the bike any more. I might give serious rides a miss for a bit, focus on building up my balance and confidence over the next week or so, hopefully I'll get some time to try some of the drills mentioned above. Thanks guys.
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Re: Mid corner puncture - why?

Postby g-boaf » Fri Feb 15, 2013 8:47 am

That's really strange - fearing turning at any speed. :( Just keep riding and don't get scared or worried about it.

Unless there is something really wrong with your bike, they are usually pretty easy to handle. Mine you could ride with your eyes closed almost, it's very stable and steady.
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Re: Mid corner puncture - why?

Postby cerb » Fri Feb 15, 2013 9:21 am

If your club runs any skills clinics i'd recommend attending. My cornering has always been decent, but it improved greatly after attending some skills sessions with the club pro.

The keys to improvement for me were:
1. Keeping my weight low (cornering on the drops with elbows bent) to lower the centre of gravity (95kg and 6'4", so my weight is fairly 'high up'!)
2. Keeping the outer leg straight through the corner and weighting this pedal
3. Don't watch the wheel in front of you - keep your vision seeking ahead around the corner.

I'm not sure that the advice to practice cornering slowly on grass would be all that beneficial as you can obviously already turn a bike at slow speeds... It sounds like confidence with cornering in a bunch at speed is more what you need?

You get more grip when you're at speed and it's easier to lay the bike over to make a tight turn. Suggest going out to a quiet street (on a dry day - wet cornering isn't a good time to gain confidence) and trying the above tips out!
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Re: Mid corner puncture - why?

Postby jacks1071 » Fri Feb 15, 2013 9:45 am

I'd get your bike and gear checked over by a mechanic to ensure its all good.

I'd also run 25mm tyres for someone your size, they'll give you a little more grip than narrower tyres.

For practice, I'd find a nice quiet block - preferably in an industrial estate or a new area. Cut laps of that block hard and fast for a few weeks like your own little crit circuit. If you can find a couple of buddies who'll pace line with you then even better.
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Re: Mid corner puncture - why?

Postby Summernight » Fri Feb 15, 2013 10:12 am

cerb wrote:[snip]

The keys to improvement for me were:
3. Don't watch the wheel in front of you - keep your vision seeking ahead around the corner.


That's one of the fundamental things taught to motorcyclists when learning to ride (well, when learning to ride at a riding school, that is):

Watch where you WANT to go and not where you don't want to go (ie. don't watch the ground or the side of the road or an obstacle in your path that you have to turn around).

It is all to do with your leaning. In a car you don't have to worry about the unconscious lean factor. On a bike and motorbike you do. Where you look is where you will go. Maybe try and look further ahead at your upcoming line when going around corners?

Practice makes perfect (or better). I still have to consciously think "ignore the parked car I'm turning around and look at where I want to go" to stop the "I'm going to hit/not going to make it!" thoughts going through my head.

I also unclip around some corners (this is at slow speeds so maybe not relevant to you) but I make sure not to take my foot off the pedal - that way I can easily clip back in again with no problems after the turn has been completed. If there is an issue that requires extra balance my foot can go down. I don't think this is useful for high speeds though.
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Re: Mid corner puncture - why?

Postby jules21 » Fri Feb 15, 2013 10:43 am

cerb wrote:3. Don't watch the wheel in front of you - keep your vision seeking ahead around the corner.

in addition to helping you corner better, there is another good reason not to focus on the wheel ahead - you will crash. in a tight (racing) bunch, you need to watch the 3-4 bikes ahead of you, it's too late to react when you notice the wheel ahead slowing down.
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Re: Mid corner puncture - why?

Postby trailgumby » Fri Feb 15, 2013 6:58 pm

sb944 wrote: I nearly had it after a few attempts, but it almost always falls to the right, which might be a sign of some huge balance issue.

This. Core strength.

I am very right side dominant, and my core strength isn't great. On steep technical climbs, where core strength is vital to muscling the bike over steep pinches, stabilising over loose patches or tight climbing switchbacks, when I get tired I get wobbly and it is almost always to the left side that I tip.

I'm guessing you're left side dominant. if you can ride no-hands your core strength is better than most, but your bike handling will improve with further focus on improving core stability and trying to gain better symmetry.

If you really want to work on bike handling, time on a mountain bike is one of the best ways to do it. At least when you come off, you won't be going nearly as quick. :wink:

The good news is that you don;t have a huge balance issue. I reckon a little work on a few areas will make a big difference.
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Re: Mid corner puncture - why?

Postby trailgumby » Fri Feb 15, 2013 7:21 pm

A further thought comes to mind.

After my over-the-bars and shoulder dislocation March 2009 I went through a period where I was very tense on unfamiliar trails, and any situation where I got anxious, like on loose corners (especially right turns) I'd reflexively shift to the back of the bike, which inevitably resulted in a skatey front end, and further anxiety. A vicious circle.

I was also having major trouble automating the weight shift to the left foot and right bar when initiating flicking the bike into right turns, I'd gotten into a very unhelpful muscle recruitment pattern with weighting my pedals in quick right-left-right-left esses or where I was surprised by the sudden appearance of a right turn. I was just getting it awfully wrong. Inevitably I had a wash-out, and it was a month before The Mont 24. I was not in a good place.

A mate on my team suggested doing figure eights in the back yard.

So I did. Hundreds of them. Small ones. Fast ones. Slow ones. Several times a week. 15-20 minutes at a time in a local cul-de-sac. Weight the foot, slide forward off the saddle and press down hard on the opposite bar, roll it in, hold, switch to the opposite side quick quick quick, jam that front into the pavement hard as you can, repeat. Dunno what the schoolkid neighbours thought, didn't care. All I saw was that imaginary figure eight line on the tarmac.

It helped enormously with my confidence and later that month I was railing the berms on Kowalski's Sideshow with panache.

I still need to go back to it sometimes, but it works.
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Re: Mid corner puncture - why?

Postby sb944 » Mon Feb 18, 2013 9:46 am

Weird, weird week. When I left this thread, I had a mis-clipin, that caused me to jam my seat down, and was feeling a little out of sorts on the bike. During lunch, I adjusted the seat back to where I thought it was (honestly I didn't know where it was). On the ride home, it felt further back, so I thought I'd adjust it when I get home. Only, I felt more balanced like this. I rode through the national park, and felt like I had a lot more control in every way. I even did a little no hands stuff on a quiet stretch, and was getting it a lot better. My confidence was really back to normal after this ride.

I also got my single speed out with the kids at Meadowbank netball courts yesterday. I usually have to drag them there, but my daughter really wanted to have a go this time, so we had a good ride around there. When they got bored I did some of the tips mentioned here. I rode as slow as I could through an imaginary slalom course, which wasn't really a problem. I did some no hands, which I could do laps of, turning in either direction without hands. I then started trying a track stand, but didn't do that for more than a few seconds before needing to topple over. This is all on the heavier, slower bike, so I still think I have a lot of work before I get the same confidence on the light roadie.

My son upstaged me though, trying to turn after going through a puddle, and ending up face first in the next puddle. He was OK, but obviously shocked and drenched.
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Re: Mid corner puncture - why?

Postby human909 » Mon Feb 18, 2013 11:19 am

sb944 wrote:I rode as slow as I could through an imaginary slalom course, which wasn't really a problem. I did some no hands, which I could do laps of, turning in either direction without hands.

If you can happily turn and ride longer distances without hands (100m++) then I would suggest that you do have decent bike skills. :mrgreen:

sb944 wrote:This is all on the heavier, slower bike, so I still think I have a lot of work before I get the same confidence on the light roadie.

I would have thought that the lighter the bike the EASIER it is to control. That is my experience. That said the geometry of a roadie does mean that the handling and control is different.

I'm at a loss on suggestions to help build your cornering. To me it just sounds like a confidence thing and a lack of faith in a grip at high speed. As long as your entry and exit is smooth you will find that you can corner extremely fast on dry tarmac with two wheel vehicles.
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Re: Mid corner puncture - why?

Postby g-boaf » Mon Feb 18, 2013 7:59 pm

sb944 wrote:Weird, weird week. When I left this thread, I had a mis-clipin, that caused me to jam my seat down, and was feeling a little out of sorts on the bike. During lunch, I adjusted the seat back to where I thought it was (honestly I didn't know where it was). On the ride home, it felt further back, so I thought I'd adjust it when I get home. Only, I felt more balanced like this. I rode through the national park, and felt like I had a lot more control in every way. I even did a little no hands stuff on a quiet stretch, and was getting it a lot better. My confidence was really back to normal after this ride.

I also got my single speed out with the kids at Meadowbank netball courts yesterday. I usually have to drag them there, but my daughter really wanted to have a go this time, so we had a good ride around there. When they got bored I did some of the tips mentioned here. I rode as slow as I could through an imaginary slalom course, which wasn't really a problem. I did some no hands, which I could do laps of, turning in either direction without hands. I then started trying a track stand, but didn't do that for more than a few seconds before needing to topple over. This is all on the heavier, slower bike, so I still think I have a lot of work before I get the same confidence on the light roadie.

My son upstaged me though, trying to turn after going through a puddle, and ending up face first in the next puddle. He was OK, but obviously shocked and drenched.


Hah - kids! ;) They just pick themselves up and away they go again. Seems like you've got your mojo back. Now go watch Tour of Oman or something like that. That always motivates me. Don't be intimidated by your road bike, they aren't all that scary. More time on it and you'll ride it like it is second nature.
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