Carbon Rim Tubular Adhesives Study

Following is the Introduction and conclusion of article that Brian (Brianero) found regarding the quality of the adhesion between a tubular tire and carbon rim when using one of several glues or Tufo tape. It is indeed very interesting.

Tubular Tire Adhesion Performance - Part 7
Examination of Tubular Tire Adhesion to Carbon Fiber Rims
Colin S. Howat
Kurata Thermodynamics Laboratory
Department of Chemical & Petroleum Engineering
1530 W 15th, Room 4132
Learned Hall
Lawrence, Kansas 66045-7609
www.engr.ku.edu/~ktl
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Abstract
Tubular tires are still the choice of many cyclists. The lighter tire/rim combination provides superior acceleration performance. The tires do not pinch flat. Many tubular tire cross sections are uniform, providing predictable cornering.
Recent trends supplant aluminum rims with carbon fiber ones. The latter provide superior stiffness for the same mass. Braking heat dissipation is problematic. Tubular tire adhesives were developed for aluminum rims. Evidence suggests adhesion to carbon fiber is inferior to adhesion to aluminum.

The purpose of this study was to quantify adhesion to carbon fiber with readily available glues. Previous studies demonstrated the superior performance of Continental glue. This glue, along with Vittoria Mastik’One, Panarace Panacement, Clement Gutta and Tufo tape, were compared. The rims used are Bontrager carbon fiber and Wolber Profil 19’s. The tires used are Continental LA’s and Competition 20’s.
Mastik’One is the best glue to use for carbon fiber rims. Continental was the worst performing of the conventional glues.

This is a laboratory study performed under laboratory conditions. Mechanics are urged to use their experience to temper the results presented herein. The mating geometry was typical but not ideal. Gluing to the edges is critical to performance when there is a protruding seam that may interfere with good contact. The safety of the rider is paramount and these results should be combined with experience to
maximize the rider safety.

Introduction

Tubular tires provide acceleration and cornering advantages over conventional
clincher tires. Further, they are not prone to sudden deflation due to pinch. They are still the tires of choice of many competitive cyclists. KTL has published six papers covering adhesive, tire, rim, application and temperature impact on adhesive performance. For all around use with aluminum rims, Continental glue was superior. It has one of the shortest times to come to full strength. It has less degradation at higher temperatures. It was one of the best for tires with and without latex coated base tapes. It was best or one of the best with non anodized and anodized aluminum rims. It did not separate during storage.

Tubular tires have two adhesive joints. The first, controlled by the tire
manufacturer, holds the base tape to the casing. The second, controlled by the mechanic, holds the base tape to the rim. Solvents in adhesives that are not designed for tubular tire installation can attack the base tape - casing joint. This attack increases the likelihoodthat the tire will roll during cornering or loss of traction situations. Readily available glues at hardware and auto supply stores may not be appropriate for tubular tire applications. Further, ones that may appear to work for some tires will not for others because of the differing properties of the base tape - casing adhesive. In general, mechanics should restrict options to those designed for tubular tire installations.

Carbon fiber with its superior stiffness to weight ratio is supplanting aluminum as
a rim material. The surface properties of carbon fiber resin are substantially different from those of aluminum. Mechanics and riders should anticipate differences in braking and tubular tire adhesion performance.

The purpose of this study is to examine adhesion to carbon fiber rims.

Materials
Six glues, two rims and two tires were used in this study.
Three of the glues - Continental, Vittoria Mastik’One and Panaracer Pana Cement
- were ‘clear’, synthetic. One, Clement Gutta, was ‘red’, natural based. One was a tape, Tufo. The last was a polyurethane based glue sold in hardware stores, Probond.
The rims were blank (no spoke holes) Profil 19’s and ‘paired-spoke’ Bontrager
Race Lite XXX. These have nearly the same cross section. The tires were Continental LA’s and Competition 20’s. These have a noticeable seam. The base tape is uncoated.
The protocol used requires a torque wrench, electrical conduit, C-clamp and tire
insert. Glue application, when applicable, was done with an ‘acid’ brush.
...

...
Conclusions

Adherence to aluminum and to carbon fiber is the same for Continental rim
cement under this testing protocol. But, the failure is more susceptible to impact failure.

Sanding carbon fiber rims prior to coating with glue provides no benefit.

Mastik’One is the best of the tested glues for carbon fiber rims.

Tufo Tape is inferior to conventional glues in both aluminum and carbon fiber
applications.

Elmer’s Probond should not be used in either application.

Gluing at the edge is of paramount importance in these applications.