מהי הקומבינציה האופטימלית....
- פותח הנושא GAD333
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אולי יקטין הסיכוי לתקר מסוג "נשיכה" (pinch Flat), אבל יגביר באופן משמעותי את הסיכוי לתקר מגופים חודרנייים ("פיצפוצי" זכוכית, ברגים, מסמרים וכו' ) ש"מעטרים" דרך קבע את שולי הכבישים. הדרך הטובה להימנע מאלו וגם מאלו היא, לנפח ל- 85% מהלחץ המקסימלי המופיע על דפנות הצמיג. לדוגמא: בצמיגי כביש בהם לח"א מקסימלי מוצהר הוא 120 פסי, עדיף לנפח עד ללחץ של 100 פסי. התנגדות הגילגול של הצמיג תגדל באופן שולי בלבד ולכן גם הביצועים לא ירדו משמעותית, אך הבונוס הוא עמידות טובה יותר בפני גופים חודרניים, תוספת ניכרת לנוחיות הרכיבה ואריכות חיים משמעותית של הצמיג. כל הנאמר לעיל הוא ע"פ דעתם של הכותבים בשבועון האלקטרוני- RBR. מצרף גם מאמר בנושא הלקוח מהגליון האחרון של הנ"ל Jim's Tech Talk: Mysteriously Frequent Punctures Question: I need suggestions for preventing punctures in winter. It's becoming a real pain fixing flats in the pouring rain. I've been running Continental Ultra Gatorskins and still been flatting about every two weeks. I'm thinking of switching to Specialized Armadillos with Slime tire liners. Can you recommend anything better? -- Masterslacker Jim Langley Replies: This question comes from the Premium Site's Roadie Rap forum on Wheels & Tires. I'm the moderator of that forum along with the one on Equipment & Maintenance. My thoughts about repeated flats might help you, too, so here's the answer I pecked out for Masterslacker: Have you inspected the tubes to find out what's causing the flats? A puncture every two weeks is pretty extreme. I ride Continental tires (Grand Prix 3000) with excellent luck, so it makes me suspect that there might be something embedded in the tire casing that's popping your new tubes. Find out by wadding up a rag and slowly sliding it around the inner circumference of each tire in both directions. It will snag on anything sharp. Then remove the thorn tip, shard of glass or sliver of wire you find. Riding in the rain certainly exposes your tires to more debris, which is washed onto the road. Even so, you should be able to see most of it and steer around things that might cause flats. It helps to brush off your tires after running through debris you can't avoid. Most punctures don't happen instantly but result from something sharp that gets stuck in the tread and works through during numerous wheel revolutions. You can knock off these bad boys by lightly laying the gloved palm of your hand on each spinning tire. Caution! To do the rear tire, hook your thumb around the frame's seatstay above the brake and then slide your hand down. This will prevent it from being pulled forward and wedged between the wheel and the seat tube. That can cause a particularly nasty crash. Maybe your punctures are being caused by "snakebites" or something inside the wheel, such as a bur in the rim or an exposed spoke hole. A snakebite -- also called a pinch flat -- is caused by hitting potholes or other abrupt things. The danger is much greater when tire pressure is too low. The impact pinches the tube between the tire and rim, cutting the tube in such a way that it looks like it got fanged by a snake. Snakebite punctures are easy to stop. You either need to top off your tire pressure before rides or, even better, stop riding into potholes, cracks, ruts and rocks. Punctures caused by something inside the rim will leave a mark on the "belly" of the tube, the inner circumference. If that's where you find the holes in your popped tubes, look for a spot where the rim strip has shifted over and exposed a spoke hole. Simply re-cover the hole's sharp edge. If the rim strip is okay, then look for burs inside the rim and file or sand them smooth. Check carefully around the weld where the rim is joined. Tip! Mount your tires so it's a little easier to find flat-causers. To do this, always put the tire label on the right side of the wheel at the valve stem. This way, you can align a patched tube with the tire and the patch will be where the culprit is. Of course, the tube could have originally been in the opposite direction, so flip it to check both ways. It's important to seek and destroy sharp things in the tire or rim. If you don't, you'll continue getting flats no matter which tires, tubes and anti-puncture products you use. ______________________________________
אולי יקטין הסיכוי לתקר מסוג "נשיכה" (pinch Flat), אבל יגביר באופן משמעותי את הסיכוי לתקר מגופים חודרנייים ("פיצפוצי" זכוכית, ברגים, מסמרים וכו' ) ש"מעטרים" דרך קבע את שולי הכבישים. הדרך הטובה להימנע מאלו וגם מאלו היא, לנפח ל- 85% מהלחץ המקסימלי המופיע על דפנות הצמיג. לדוגמא: בצמיגי כביש בהם לח"א מקסימלי מוצהר הוא 120 פסי, עדיף לנפח עד ללחץ של 100 פסי. התנגדות הגילגול של הצמיג תגדל באופן שולי בלבד ולכן גם הביצועים לא ירדו משמעותית, אך הבונוס הוא עמידות טובה יותר בפני גופים חודרניים, תוספת ניכרת לנוחיות הרכיבה ואריכות חיים משמעותית של הצמיג. כל הנאמר לעיל הוא ע"פ דעתם של הכותבים בשבועון האלקטרוני- RBR. מצרף גם מאמר בנושא הלקוח מהגליון האחרון של הנ"ל Jim's Tech Talk: Mysteriously Frequent Punctures Question: I need suggestions for preventing punctures in winter. It's becoming a real pain fixing flats in the pouring rain. I've been running Continental Ultra Gatorskins and still been flatting about every two weeks. I'm thinking of switching to Specialized Armadillos with Slime tire liners. Can you recommend anything better? -- Masterslacker Jim Langley Replies: This question comes from the Premium Site's Roadie Rap forum on Wheels & Tires. I'm the moderator of that forum along with the one on Equipment & Maintenance. My thoughts about repeated flats might help you, too, so here's the answer I pecked out for Masterslacker: Have you inspected the tubes to find out what's causing the flats? A puncture every two weeks is pretty extreme. I ride Continental tires (Grand Prix 3000) with excellent luck, so it makes me suspect that there might be something embedded in the tire casing that's popping your new tubes. Find out by wadding up a rag and slowly sliding it around the inner circumference of each tire in both directions. It will snag on anything sharp. Then remove the thorn tip, shard of glass or sliver of wire you find. Riding in the rain certainly exposes your tires to more debris, which is washed onto the road. Even so, you should be able to see most of it and steer around things that might cause flats. It helps to brush off your tires after running through debris you can't avoid. Most punctures don't happen instantly but result from something sharp that gets stuck in the tread and works through during numerous wheel revolutions. You can knock off these bad boys by lightly laying the gloved palm of your hand on each spinning tire. Caution! To do the rear tire, hook your thumb around the frame's seatstay above the brake and then slide your hand down. This will prevent it from being pulled forward and wedged between the wheel and the seat tube. That can cause a particularly nasty crash. Maybe your punctures are being caused by "snakebites" or something inside the wheel, such as a bur in the rim or an exposed spoke hole. A snakebite -- also called a pinch flat -- is caused by hitting potholes or other abrupt things. The danger is much greater when tire pressure is too low. The impact pinches the tube between the tire and rim, cutting the tube in such a way that it looks like it got fanged by a snake. Snakebite punctures are easy to stop. You either need to top off your tire pressure before rides or, even better, stop riding into potholes, cracks, ruts and rocks. Punctures caused by something inside the rim will leave a mark on the "belly" of the tube, the inner circumference. If that's where you find the holes in your popped tubes, look for a spot where the rim strip has shifted over and exposed a spoke hole. Simply re-cover the hole's sharp edge. If the rim strip is okay, then look for burs inside the rim and file or sand them smooth. Check carefully around the weld where the rim is joined. Tip! Mount your tires so it's a little easier to find flat-causers. To do this, always put the tire label on the right side of the wheel at the valve stem. This way, you can align a patched tube with the tire and the patch will be where the culprit is. Of course, the tube could have originally been in the opposite direction, so flip it to check both ways. It's important to seek and destroy sharp things in the tire or rim. If you don't, you'll continue getting flats no matter which tires, tubes and anti-puncture products you use. ______________________________________
ועוד מאמר בנושא מאותו הניוזלטר
The Case for Lower Tire Pressure DEAR UNCLE AL: Perhaps you can settle an argument at our bike club. I like riding 20-mm-wide tires inflated to 120-130 pounds. I feel faster because of what I think is lower rolling resistance. Others argue for a 23C width at 100-110 psi, saying these tires are more efficient because they absorb pavement irregularities better. I weigh 175 pounds and ride at an average of 18+ mph on a variety of road surfaces. So who's right about width and pressure? -- Greg C. UNCLE AL FIRES BACK: Soften up, Greg! Most everyone I know runs too much pressure. Welcome to the club. Over many years of testing and talking to guys who live on their bikes, I'm convinced there is little reason to run more than 95-100 psi -- and there are compelling reasons to run 85-90 psi. High pressure, say 100-120 psi, guarantees short tire life, poor cornering and lots of punctures. A rock-solid tire cuts/punctures more easily than it would at a lower pressure. Also, a softer tire can "smear" -- conform better to objects encountered on the road. Why make the ride even rougher on America's ever-crumbling road surfaces? Admittedly, I weigh 210 pounds and ride on really poor road surfaces. These things influence my opinions. I run 85-90 psi front and 90-95 psi rear on 700x23C clincher tires. I do not have flats! Plus, bumps are less of an issue, and my bike corners as if on rails on high-speed descents. I get 1,000-1,500 miles out of a rear tire. When I ran much higher pressure many years ago, I got no more than 500 miles. So, my advice is never to run smaller than 23C. Use good tubes, air them up before every ride and spend extra for premium tires -- they'll pay you back in extra mileage and better handling. One more thing: Don't buy a race-specific tire to train on. If it's advertised to last only 500 miles, they aren't lying. Shaving grams off of training tires is silly and wasteful, and you won't get the low-weight advantage when event time comes if you ride the light stuff all the time. Make gram shaving your secret weapon, if only in your mind, when it counts. Do as I recommend and I promise fewer flats, happier miles and no noticeable increase in rolling resistance (the great myth). Plus, you'll waste fewer resources, both financial and natural. FEEDBACK FROM ARNIE L.: As a roadie of 20+ years, but a new reader of RoadBikeRider, I was intrigued (and skeptical) of your advice to lower tire pressure. I have been riding at 125 psi or more, concerned about rolling resistance (although the extra 10 pounds around my waist probably matters a whole lot more to my performance). Well, I thought I'd try it. I lowered my pressure to 105 psi. What a great difference! I haven't really noticed any change in performance, but what a difference in the ride! One of my usual rides over badly cracked roads (usual Pennsylvania stuff) was sooo much more comfortable. It seemed like the road had been repaved. Thanks for the advice. FEEDBACK FROM MICHAEL A.: Recently, a friend told me about your promotion of lower tire pressure. GREAT! In the early 1960s, I rode the kermesses around Antwerp for a team sponsored by "Cycles OK." We always rode tubulars at about 90 psi with great results -- fewer flats and better handling, especially in the rain (a frequent occurrence in Flanders). I've tried to promote lower pressure as a coach with the New York Cycle Club, with little success. My fellow club members see my gray hair and my inability to keep up with the hormonally besot, and reject my advice. It's great that you're putting out this sound advice. FEEDBACK FROM SAL A.: I've been riding for years with high pressures in my 23C tires (120-130 psi rear, 100-110 psi front). I figured since I weigh around 215 pounds I need this. I was pleasantly surprised to find out how much better my bike rides after lowering the pressures as Uncle Al recommends. I rode over some freshly "chipped" roads on my latest ride. This is where the road is covered with hot tar and then pea stone is spread on top. It makes for pretty anxious riding, especially down hills. I was really happy with the improvement in handling. Also, on smooth asphalt the tires now “sing” lightly. They never did that before! I like the sound and it seems to confirm that I'm riding with the right tire pressure. I love when I learn something new about bicycling, especially when it's simple and effective. My helmet's off to Uncle Al.
The Case for Lower Tire Pressure DEAR UNCLE AL: Perhaps you can settle an argument at our bike club. I like riding 20-mm-wide tires inflated to 120-130 pounds. I feel faster because of what I think is lower rolling resistance. Others argue for a 23C width at 100-110 psi, saying these tires are more efficient because they absorb pavement irregularities better. I weigh 175 pounds and ride at an average of 18+ mph on a variety of road surfaces. So who's right about width and pressure? -- Greg C. UNCLE AL FIRES BACK: Soften up, Greg! Most everyone I know runs too much pressure. Welcome to the club. Over many years of testing and talking to guys who live on their bikes, I'm convinced there is little reason to run more than 95-100 psi -- and there are compelling reasons to run 85-90 psi. High pressure, say 100-120 psi, guarantees short tire life, poor cornering and lots of punctures. A rock-solid tire cuts/punctures more easily than it would at a lower pressure. Also, a softer tire can "smear" -- conform better to objects encountered on the road. Why make the ride even rougher on America's ever-crumbling road surfaces? Admittedly, I weigh 210 pounds and ride on really poor road surfaces. These things influence my opinions. I run 85-90 psi front and 90-95 psi rear on 700x23C clincher tires. I do not have flats! Plus, bumps are less of an issue, and my bike corners as if on rails on high-speed descents. I get 1,000-1,500 miles out of a rear tire. When I ran much higher pressure many years ago, I got no more than 500 miles. So, my advice is never to run smaller than 23C. Use good tubes, air them up before every ride and spend extra for premium tires -- they'll pay you back in extra mileage and better handling. One more thing: Don't buy a race-specific tire to train on. If it's advertised to last only 500 miles, they aren't lying. Shaving grams off of training tires is silly and wasteful, and you won't get the low-weight advantage when event time comes if you ride the light stuff all the time. Make gram shaving your secret weapon, if only in your mind, when it counts. Do as I recommend and I promise fewer flats, happier miles and no noticeable increase in rolling resistance (the great myth). Plus, you'll waste fewer resources, both financial and natural. FEEDBACK FROM ARNIE L.: As a roadie of 20+ years, but a new reader of RoadBikeRider, I was intrigued (and skeptical) of your advice to lower tire pressure. I have been riding at 125 psi or more, concerned about rolling resistance (although the extra 10 pounds around my waist probably matters a whole lot more to my performance). Well, I thought I'd try it. I lowered my pressure to 105 psi. What a great difference! I haven't really noticed any change in performance, but what a difference in the ride! One of my usual rides over badly cracked roads (usual Pennsylvania stuff) was sooo much more comfortable. It seemed like the road had been repaved. Thanks for the advice. FEEDBACK FROM MICHAEL A.: Recently, a friend told me about your promotion of lower tire pressure. GREAT! In the early 1960s, I rode the kermesses around Antwerp for a team sponsored by "Cycles OK." We always rode tubulars at about 90 psi with great results -- fewer flats and better handling, especially in the rain (a frequent occurrence in Flanders). I've tried to promote lower pressure as a coach with the New York Cycle Club, with little success. My fellow club members see my gray hair and my inability to keep up with the hormonally besot, and reject my advice. It's great that you're putting out this sound advice. FEEDBACK FROM SAL A.: I've been riding for years with high pressures in my 23C tires (120-130 psi rear, 100-110 psi front). I figured since I weigh around 215 pounds I need this. I was pleasantly surprised to find out how much better my bike rides after lowering the pressures as Uncle Al recommends. I rode over some freshly "chipped" roads on my latest ride. This is where the road is covered with hot tar and then pea stone is spread on top. It makes for pretty anxious riding, especially down hills. I was really happy with the improvement in handling. Also, on smooth asphalt the tires now “sing” lightly. They never did that before! I like the sound and it seems to confirm that I'm riding with the right tire pressure. I love when I learn something new about bicycling, especially when it's simple and effective. My helmet's off to Uncle Al.
ואני טוען שהשיטה שלי הכי טובה
אני רוכב בלי הגזמה , אלפי ק"מ בלי שום פנצ'ר וזה מאוד פשוט.רוכב לבד.אני רואה בדיוק לאן אני רוכב רואה את הדרך ובמידה ויש זכוכיות או משהו דומה פשוט עוקף.קרה לי מקרה לפני חצי שנה בערך, הגיע אלי חבר שגר בספרד (כשאני שם אני לפעמים רוכב בחברתו),ארגנתי לו זוג נוסף ויצאנו לרכיבה משותפת . באותה רכיבה קיבלתי אח'לה תקר,ואני מייחס אותו לחוסר תשומת הלב למה שקרה על הכביש שהיינו ביחד.מה יכולתי לעשות ,חבר מדבר איתי ,לא נעים. כמובן שגם סוג הצמיג חשוב ולחץ אויר חשוב,הכל נכון, אבל תשומת הלב לדרך היא לדעתי הכי חשובה.
אני רוכב בלי הגזמה , אלפי ק"מ בלי שום פנצ'ר וזה מאוד פשוט.רוכב לבד.אני רואה בדיוק לאן אני רוכב רואה את הדרך ובמידה ויש זכוכיות או משהו דומה פשוט עוקף.קרה לי מקרה לפני חצי שנה בערך, הגיע אלי חבר שגר בספרד (כשאני שם אני לפעמים רוכב בחברתו),ארגנתי לו זוג נוסף ויצאנו לרכיבה משותפת . באותה רכיבה קיבלתי אח'לה תקר,ואני מייחס אותו לחוסר תשומת הלב למה שקרה על הכביש שהיינו ביחד.מה יכולתי לעשות ,חבר מדבר איתי ,לא נעים. כמובן שגם סוג הצמיג חשוב ולחץ אויר חשוב,הכל נכון, אבל תשומת הלב לדרך היא לדעתי הכי חשובה.
פנצר זה עניין של מזל ושכל
הממוצע שלי הוא בערך פמצר אחד אחת ל2000 ק"מ ואני בהחלט מנפח למקסימום לא פחות מ120PSI פשוט צריך להסתכל להיכן רוכבים לא יותר מזה. לגבי הלחצים אני לא מסכים וטוען שישנה חזיבות ללחצים אני למשל לרגיש את ההבדל בין 110 ל120 בקלות. לא הייתי מוכן לטפס את נס הרים עם פחות מ120, בייחוד בעליות שבהן נדרשת רכיבה בעמידה אז רוב המשקל עובר לגלגל הקדמי.
הממוצע שלי הוא בערך פמצר אחד אחת ל2000 ק"מ ואני בהחלט מנפח למקסימום לא פחות מ120PSI פשוט צריך להסתכל להיכן רוכבים לא יותר מזה. לגבי הלחצים אני לא מסכים וטוען שישנה חזיבות ללחצים אני למשל לרגיש את ההבדל בין 110 ל120 בקלות. לא הייתי מוכן לטפס את נס הרים עם פחות מ120, בייחוד בעליות שבהן נדרשת רכיבה בעמידה אז רוב המשקל עובר לגלגל הקדמי.
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במוצא"ש ...זה בערך הזמן שלקח לי להפשיר
מרכיבת הטרום בוקר
...שמתי לב שפיספסת איזשהו מרתון ספינינג...שתפי אותי להבא
וברצינות...אני רואה שאף אחד כאן לא מחסידי פס גומי/ גיפה...האם רחמא ליצלן
בגלל תוס' המשקל??? האם בגלל לחץ האויר הגבוה הגיפה איננה אפקטיבית? תודה על התשובות
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אני ניסיתי פנימית עם חומר
זה קרה בתקופה שלא נגמרו לי הפאנצ'רים, כל רכיבה החלפתי פנימית. אמרתי למה לא, אני אשקיע 50 ש"ח, אם יגמרו הפאנצ'רים זה שווה את ההוצאה. הבעיה העיקרית שלי עם פנימית עם חומר היתה, שהונטיל פשוט נסתם לי כל הזמן. זה הגיע למצב שאני לא יכול לנפח את הגלגל לפני רכיבה, מהר מאוד התייאשתי (יש לי פנימית אחת נוספת עם חומר שלא השתמשתי בה). החלפתי צמיג אחורי, וטפו טפו טפו טפו טפו טפו בנתיים לא היו פאנצ'רים.
זה קרה בתקופה שלא נגמרו לי הפאנצ'רים, כל רכיבה החלפתי פנימית. אמרתי למה לא, אני אשקיע 50 ש"ח, אם יגמרו הפאנצ'רים זה שווה את ההוצאה. הבעיה העיקרית שלי עם פנימית עם חומר היתה, שהונטיל פשוט נסתם לי כל הזמן. זה הגיע למצב שאני לא יכול לנפח את הגלגל לפני רכיבה, מהר מאוד התייאשתי (יש לי פנימית אחת נוספת עם חומר שלא השתמשתי בה). החלפתי צמיג אחורי, וטפו טפו טפו טפו טפו טפו בנתיים לא היו פאנצ'רים.
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לו הצמיג היה יכול לדבר הוא היה אומר
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"זה לא אתה זה אני"
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