Search found 177 matches

by Winkeladvokat
17 Aug 2011, 7:48pm
Forum: Bikes & Bits – Technical section
Topic: ROAD TIRE PRESSURE AND PUNCTURES
Replies: 54
Views: 5486

Re: ROAD TIRE PRESSURE AND PUNCTURES

The contact patch increases quite a bit more in length than in width with a reduction in pressure. Does it? At a first guess, I'd expect the length and width to both increase as the square root of the area. You may know different. Simply (geometrically, considering angles, assuming the casing is no...
by Winkeladvokat
17 Aug 2011, 7:42pm
Forum: Bikes & Bits – Technical section
Topic: ROAD TIRE PRESSURE AND PUNCTURES
Replies: 54
Views: 5486

Re: ROAD TIRE PRESSURE AND PUNCTURES

You seem to be happy that you can model the likelihood of punctures just using the pressure of the tyre against the shard. I don't know whether you can or not, but I can think of many scenarios where it might not be valid. I genuinely cannot think of a single situation where that might be the case....
by Winkeladvokat
17 Aug 2011, 5:13pm
Forum: Bikes & Bits – Technical section
Topic: ROAD TIRE PRESSURE AND PUNCTURES
Replies: 54
Views: 5486

Re: ROAD TIRE PRESSURE AND PUNCTURES

Increasing pressure will decrease the contact area, which will increase the pressure (and force) on a given piece of glass. However, it will also decrease the probability of running over a given piece of glass. Marginally. The contact patch increases quite a bit more in length than in width with a ...
by Winkeladvokat
17 Aug 2011, 5:11pm
Forum: Bikes & Bits – Technical section
Topic: ROAD TIRE PRESSURE AND PUNCTURES
Replies: 54
Views: 5486

Re: ROAD TIRE PRESSURE AND PUNCTURES

It seems intuitive to me that there's a relationship between pressure and penetration - so happy to take that as a given. What I don't understand is what other factors contribute to penetration and how they're affected by tyre pressure. Without knowing that I wouldn't like to say that I know the me...
by Winkeladvokat
17 Aug 2011, 4:10pm
Forum: Bikes & Bits – Technical section
Topic: ROAD TIRE PRESSURE AND PUNCTURES
Replies: 54
Views: 5486

Re: ROAD TIRE PRESSURE AND PUNCTURES

then deformation may aid the process of embedding the shard in the tyre initially to facilitate this happening. In which case the contact pressure goes down. I.e. given a give contact pressure distribution with no foreign objects/deformation, the question is what's the degree of deformation and wha...
by Winkeladvokat
17 Aug 2011, 2:25pm
Forum: Bikes & Bits – Technical section
Topic: ROAD TIRE PRESSURE AND PUNCTURES
Replies: 54
Views: 5486

Re: ROAD TIRE PRESSURE AND PUNCTURES

Sorry, that's wrong. The rider+bike weight is supported by the contact patch on the tyre, and the tyre contact patch size is determined by the contact patch pressure for a given load. (The one subtlety here is that contact patch pressure is not the same as tyre pressure, due to physical properties o...
by Winkeladvokat
17 Aug 2011, 1:28pm
Forum: Bikes & Bits – Technical section
Topic: ROAD TIRE PRESSURE AND PUNCTURES
Replies: 54
Views: 5486

Re: ROAD TIRE PRESSURE AND PUNCTURES

No!!!!! All the advice to keep the tyres pumped hard is wrong!!!! Pinch flats are caused by low pressure, this is true. The risk of penetration punctures, on the other hand, increases with higher pressure!!!! The reason: higher pressure increases the force on the little shard of glass, allowing it t...
by Winkeladvokat
8 Jun 2011, 2:12pm
Forum: Does anyone know … ?
Topic: Lower Back Pain
Replies: 17
Views: 1492

Re: Lower Back Pain

Yeah, I'd second that, your position isn't a million miles off. If anything your saddle drop is quite conservative and you could probably afford to drop the bars a little more. Also, compact bars don't seem to be doing you any favours, because they're bringing your hands quite far back when in the d...
by Winkeladvokat
5 Jun 2011, 9:23am
Forum: Does anyone know … ?
Topic: Lower Back Pain
Replies: 17
Views: 1492

Re: Lower Back Pain

Tom, This is likely to be a fit issue. Any chance of a photo of your bike with or without you on it? Being too stretched out or having too much saddle drop, particularly if you're spending lots of time on the drops, can make your lower back suffer. The reason is to do with the hips - too tight a hip...
by Winkeladvokat
22 May 2011, 11:29am
Forum: Does anyone know … ?
Topic: Why some cyclists would not greet you when they overtake you
Replies: 59
Views: 4950

Re: Why some cyclists would not greet you when they overtake

I generally always say hi when passing but occasionally do not. On those occasions: a) I'm either busting my balls on a fast ride and am too focused/knackered to register. b) The comments above about making the passed person annoyed ring true, especially if it's on a hill and you're obviously on a m...
by Winkeladvokat
17 May 2011, 10:37pm
Forum: Does anyone know … ?
Topic: V-CC what are your experiences ?
Replies: 33
Views: 2518

Re: V-CC what are your experiences ?

I'm with snibgo, life's too short to be dealing with messed-up social groupings and cliques. Clubs can be great when they're based on mutual respect and when people feel motivated and are able to contribute for the benefit of other members - in this way they can become greater than the sum of their ...
by Winkeladvokat
16 May 2011, 1:32pm
Forum: Does anyone know … ?
Topic: Knock knees
Replies: 10
Views: 1588

Re: Knock knees

531colin wrote:ITB = ileo-tibial band?


Yes, exactly.
by Winkeladvokat
16 May 2011, 1:24pm
Forum: Does anyone know … ?
Topic: Knock knees
Replies: 10
Views: 1588

Re: Knock knees

I find your question interesting because being an avid watcher of the big races on Eurosport I noticed some time ago that the riders knees all seem to be close to the top tube and I even Twittered David Hammond to ask whether it was because the bikes they rode had shorter bottom brackets and whethe...
by Winkeladvokat
16 May 2011, 12:04pm
Forum: Does anyone know … ?
Topic: Knock knees
Replies: 10
Views: 1588

Re: Knock knees

Having knees that don't move in a straight line isn't particularly great, for two reasons: loading the knee with the femur falling inwards increases the loading on the patellar tendon, and increases the risk of patellar tendonitis issues; the femur falling inwards is a sign of weak glutes, and this ...
by Winkeladvokat
13 May 2011, 11:18am
Forum: Does anyone know … ?
Topic: Patellar Tendinopathy :evil:
Replies: 5
Views: 539

Re: Patellar Tendinopathy :evil:

There's an extremely effetive protocol that involves single leg eccentric squats (i.e. the lowering phase) with the heel raised (e.g. on a decline board). It's slightly painful and you need to do a lot of it, but it does work in that the long term outcome is good. I would, however, suggest that you ...