<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> TUBULAR TIRES: ADHESIVES AND PRACTICE C. Calvin Jones Barnett Bicycle Institute Colorado Springs, Colorado Colin S. Howat Ph.D., P.E. Kurata Thermodynamics Laboratory Department of Chemical & Petroleum Engineering University of Kansas Lawrence, Kansas 66045-2223 howat@cpe.engr.ukans.edu INTRODUCTION Historically, tubular tires, 'sew-ups', have been the tire of choice for competitive cycling. While the modern clincher tire-rim combination can compete with the pressures, rolling resistance's, handling and ease of repair with the tubular, the tubular tire-rim combination will always be lighter than the clincher tire-rim combination. With the lightest clincher rim being easily 100 grams heavier than the lightest tubular and with most clincher tire/tube combinations heavier than tubulars, the lightness of the tubular tire-rim leads to less resistance to acceleration and braking -- the 'jump' to which tubular aficionados refer -- as well as making the total weight of the bicycle less. An additional advantage is that the tubular tire design is very resistant to 'rim-pinch' (snakebite) type flats. As the clincher tire developments have advanced, tubulars have become less popular -- largely because of the perceived difficulties in mounting and the difficulties in repairing flats. We believe that the significant advantages of rim-tire weight will continue to make tubular tires attractive to cyclists and, consequently, their use will continue. The principal short-coming, then, is the proper mounting of tubulars to minimize the probability that they will 'roll-off' the rim -- usually at inopportune times such as high-speed descents, corners or banks. The mounting of tubular tires is critical to the rider's safety. The adhesive bond between the rim and tire must resist lateral loads that result from cornering, banking or catching a pedal in a corner and skidding. Despite the best of efforts, a well-glued tubular may still roll. However, there are steps that a rider can take to minimize that chance by using the proper adhesives and the proper application procedure. In this article, we discuss the results of our experience in the laboratory and on the road. The full article appeared in CUSA. Jones, C.C., and Howat, C.S., 1995. Tubular Tires: Adhesives and Practice.Cycling USA, Part 1: XVII(8): 9. Part 2: XVII(9): 16. Part 3: XVII(10): 18. Part 4: XVII(11): 23. Status Report 1: Tubular Tire Performance Analysis Beum (Sam) S. Sul And Colin S. Howat PhD, PE Kurata Thermodynamics Laboratory Department Of Chemical & Petroleum Engineering University Of Kansas Lawrence, Ks 66045 howat@cpe.engr.ukans.edu July 29, 1992 I. SUMMARY Catastrophic failure of adhesion between tubular tires and rims can result in severe injury to the bicyclist. Static and dynamic roll-off experiments are being conducted at the Kurata Thermodynamics Laboratory of the University of Kansas. The purpose of these experiments is to determine the effect on performance of adhesive, tire, and rim combinations. Independent variables are: Operating Temperature Moisture Exposure Curing Time Gluing Procedure The purpose of the initial experiments was: 1) to develop a repeatable static roll-off experimental procedure; and, 2) to perform preliminary experiments examining the above parameters. Initial results reported herein. The following adhesives were tested: Clement Gutta Extra Continental Rim Cement Special 3M Fast Tack Trim Adhesive Tubasti Mastice Gutta DeLuxe Rim Cement Vittoria Mastice Gutta Cement Vittoria Mastik'One Professional Wolber Tubular Rim Glue Tire type was D'Alessandro Advent for all experiments. Mavic anodized, unanodized and "hard" anodized aluminum rims were used. An "X" in Table I.1 lists the type of experiments performed for each adhesive. The gluing procedure used was that prescribed by Barnett Bicycle Institute distributed at the USCF Mechanics Clinic. The static test involved using 80 mm sections of rim, tire, and flexible, SCH 40 conduit. The conduit maintains tire shape as air would in a complete tire. The 80 mm length was determined to be of sufficient length to differentiate among adhesives. Roll- off load, rim adhesive failure and base tape failure were measured. Repeatability experiments were performed to test all of the adhesives on each of the three rim types. The primary purpose was to verify experimental precision. The secondary purpose was to give a preliminary indication of adhesive strength. Tables I.2 - I.4 list the results. Table I.1: Preliminary Experiments for Each Adhesive ON> Variable Tested Adhesive/th> Rim Repeat Temp Water Re-Glue Curing Clement X X Continental X X X 3M Fast Tack X X Tubasti X X X X X X Vittoria Gutta X X Vittoria Mastik'One X X X X X X Wolber X X Table I.2: Relative Strength for Adhesives Tested with Anodized Aluminum Rim ON> ON> Adhesive No. of Samples Mean (lb in) Standard Deviation (lb in) Average Rim Percentage Failure Base Tape Vittoria Mastik'One 3 40.8 2.4 5 50 Continental 3 30.0 2.0 30 30 Clement 3 29.6 2.1 0 65 Vittoria Gutta 5 25.5 1.9 80 >5 3M Fast Tack 3 25.4 0.6 50 5 Wolber 5 20.5 1.0 30 Trace Tubasti 5 18.6 1.3 20 0 Table I.3: Relative Strength for Adhesives Tested with Unanodized Aluminum Rim ON> Adhesive No. of Samples Mean (lb in) Standard Deviation (lb in) Average Rim Percentage Failure Base Tape Vittoria Mastik'One 3 37.5 2.0 5 75 Continental 3 32.5 2.0 40 25 Clement 3 31.3 1.0 0 70 Vittoria Gutta 3 27.5 1.0 90 0 3M Fast Tack 3 23.3 1.2 70 5 Wolber 3 22.9 0.6 15 30 Tubasti 3 16.7 1.2 30 >5 Table I.4: Relative Strength for Adhesives Tested with Hard Anodized Aluminum Rim ON> Adhesive No. of Samples Mean (lb in) Standard Deviation (lb in) Average Rim Percentage Failure Base Tape Vittoria Mastik'One 3 34.2 2.4 >5 35 Clement 3 32.1 1.2 Trace 60 Continental 3 31.7 1.6 35 20 3M Fast Tack 3 28.3 1.2 60 15 Vittoria Gutta 3 25.0 1.0 80 0 Tubasti 3 22.5 2.0 10 25 Wolber 3 19.2 1.2 40 Trace Table I.5 and Figure I.1 summarize the mean static roll-off load for all adhesives with the three rim types. Table I.5: Mean Roll-off Loads as a Function of Rim Type ON> Adhesive Anodized Unanodized Hard Anodized Vittoria Mastik'One 40.8 37.5 34.2 Continental 30.0 32.5 31.7 Clement 29.6 31.3 32.1 Vittoria Gutta 25.5 27.5 25.0 3M Fast Tack 25.4 23.3 28.3 Wolber 20.5 16.7 19.2 Tubasti 18.6 22.9 22.5 The relative adhesive strengths among the adhesives for the three rim types did not change significantly. However, differences between rim-types for a specific adhesive are statistically significant, most notably Tubasti and 3M Fast Tack. Tables I.6 and I.7 summarize the preliminary experiments during which the effects of temperature, moisture exposure, and re-gluing were measured. For the temperature experiments, the cured samples were held at 50?C (122?F) for 0.5 hours. Roll-off measurements were conducted before cooling. For the water immersion experiments, samples were placed in a room temperature water bath for 5 hours. Roll-off measurements were conducted with the sample wet. For the re-gluing measurements, a new tire section with a single coat of Table I.6: Roll-Off Load Experiments for Various Conditions with Vittoria Mastik'One Adhesive ON> Adhesive Condition No. of Samples Mean (lb in) Standard Deviation (lb in) Average Rim Percentage Failure Base Tape Vittoria Mastik'One Repeat 3 40.8 2.4 5 50 Temp 3 28.8 1.0 30 40 Water 3 32.5 2.0 >5 0 Re-Glue 3 40.8 2.4 50 10 Table I.7: Roll-Off Load Experiments for Various Conditions with Tubasti Adhesive ON> Adhesive Condition No. of Samples Mean (lb in) Standard Deviation (lb in) Average Rim Percentage Failure Base Tape Tubasti Repeat 5 18.6 1.3 20 0 Temp 3 11.7 1.2 20 0 Water 3 11.7 1.2 75 0 Re-Glue 3 16.3 1.0 35 0 adhesive was glued to a rim section which had been previously used, had not been cleaned but had receive an additional coat of adhesive. Higher temperature decreased the roll-off loads. While the water immersion tests indicate that moisture reduces the adhesive bond, the experimental procedure needs to be modified: the entire sample was immersed in water allowing water to seep from the inside of the tire to the base tape and rim. This does not properly represent on-bike conditions and, therefore, the results should be considered qualitatively and not quantitatively correct. The re-glue test for Vittoria Mastik'One did not change roll-off loads. Rim adhesive failure increased but base tape failure decreased. For Tubasti, the re-glue lowered roll-off loads. Table I.8 shows a preliminary curing time study for Continental and Wolber adhesives. This set of measurements were made prior to settling on 80 mm rim section lengths. Consequently, these results are not directly comparable to those in previous tables. Note that the Continental strength appears to be increasing with time. This indicates that the experiment will need longer curing times. The results presented in this report are preliminary. They demonstrate that the static procedure is precise and that it can be used to distinguish Table I.8: Preliminary Curing Time Study with Continental and Wolber ON> Roll-Off Loads (lb-in) Time (hrs) Coninental Wolber 1 17.5 10.0 2 20.0 13.8 3 20.0 17.3 6 22.5 18.5 12 22.5 17.3 24 27.5 15.0 NOTE: 60 mm anodized aluminum sections used for Continental 100 mm sections for Wolber among the glue/rim adhesive performance and to determine the effects of operating temperature, moisture and re-gluing. The experiments will be repeated for all combinations of adhesives, rims and tires. The effects of the independent variables with all combinations will be examined. Sul, B.S., and Howat, C.S., 1992. Tubular Tire Performance Analysis, Status Report 1. Report to the United States Cycling Federation, Colorado Springs, Colorado. Status Report 2: Preliminary Static Tests Subsequent To Status Report 1 Beum (Sam) S. Sul And Colin S. Howat PhD, PE Kurata Thermodynamics Laboratory Department Of Chemical & Petroleum Engineering University Of Kansas Lawrence, Ks 66045 howat@cpe.engr.ukans.edu OCTOBER 08, 1992 I. PURPOSE The purpose of this report is three-fold. The first is to present measurements which have been conducted after those reported in Status Report 1 dated 7/29/92. The second is to present the schematic of the dynamic experimental equipment which is under construction at KTL. The third is to list the needs for completing the experimental program. Sul, B.S., and Howat, C.S., 1992. Tubular Tire Performance Analysis, Status Report 2: Preliminary Static Tests Subsequent to Status Report 1. Report to the United States Cycling Federation, Colorado Springs, Colorado. STATUS REPORT 3: TUBULAR TIRE PERFORMANCE ANALYSIS Beum (Sam) S. Sul And Colin S. Howat PhD, PE Kurata Thermodynamics Laboratory Department Of Chemical & Petroleum Engineering University Of Kansas Lawrence, Ks 66045 howat@cpe.engr.ukans.edu February 9, 1993 I. SUMMARY The purpose of this report is two-fold: First, it is to present measurements which have been conducted after those reported in Status Report 2 dated 8/8/92. Second, it is to discuss the effect of rim type, tire type and gluing procedure on adhesive performance. Results of the following static experiments are summarized herein. A. Repeatability with Vittoria Corsa CX Tires B. Repeatability with Continental Sprinter 250 Tires C. Repeatability using Manufacturers' Gluing Procedures D. Repeatability with D'Alessandro Tires, Hard Anodized Rims and Pana Cement E. Summary of Repeatability Data and Statistical Test The statistical tests performed on the repeatability data tested the significance among means for each adhesive, rim and tire combination. Seven adhesives were used in experiments A, B, and C with both anodized and hard anodized aluminum rims. The seven adhesives are: Vittoria Mastik'One Professional Continental Rim Cement Special Clement Gutta Extra Vittoria Mastice Gutta Cement 3M Fast Tack Trim Adhesive Pana Cement Wolber Tubular Rim Glue The Barnett Bicycle Institute gluing procedure was used for A, B, and D. The manufacturers' recommended gluing procedure was used for experiment C. There are two types of failure modes reported in this summary. First, Average Percentage Failure Rim is the average area percentage failure of the adhesive bond to the rim surface. For example, 90% failure means that 90% of the rim surface was clean of adhesive after roll-off: only 10% of the rim surface area still had adhesive after roll-off. Second, Average Percentage Failure BT Fabric is a measure of the area of the adhesive on the rim with impregnated Base Tape fibers. The percentage is of the total rim area whether adhesive was present on all of the area or not. These are the same failures as that reported in Status Reports 1 and 2. Sul, B.S., and Howat, C.S., 1993. Tubular Tire Performance Analysis, Status Report 3. Report to United States Cycling Federation, Colorado Springs, Colorado.
