All The responses provided a wealth of tire pressures for 32mm and 38mm tires. 12 list members responded with reported rider weights, and actual 32mm and 38mm front & rear tire pressures. I put the information into an Excel file and compared the actual tire pressures to the tire pressures calculated using F Berto's 15% Tire Drop method assuming the following: 1. The 12 members reported the RIDER weight, not the total bike weight. I used a 26 lb BIKE weight (typical road lightweight steel tubing) to get th TOTAl weight for the calculation 2. I used 45%/55% front/rear distribution for all members except 1 who reported an Upright use on 38mm tire (used a 40/60 split for this) 3. I used the 32mm curve Berto published for the 32mm tire and used an extrapolation for the 38mm tire. I caluated the front and rear pressures based n the front and rear weights (using the distribution) and a slope and intercept for each tire size, i.e., pressure = slope * weight + intercept
The executive summary is: The majority of the riders tire pressures are with 6 to 8 psig of the pressures calculated by Berto's method. There were 5 outliers out of 24 pressures reported (12 reports x 2 pressures per report), see below. This indicates the majority of the responders are using tire pressures based on the 15% tire drop method. The 32mm uses tend to OVER Inflate the Front tire and UNDER Inflate the REAR tire wrt to Berto's method. The 32mm users may want to verify their Rear pressures wrt to Berto's method. The 38mm tire users tend to inflate both Front and Rear closer to Berto's method than the 32mm users. The 4 outliers were: 1 32mm user over inflated the Front by 11 psi 2 32 mm users under inflated the Rear by 9 psi and 11 psi 1 38mm user under inflated the Front and Rear by 14 and 24 psig respectively. If any one reported Total Weight or has a weight distribution other the 45%/55% F/R (except for the 1 38mm case of an upright), let me know and I will adjust the file. I purposely did NOT include the Excel file since the list members responding did not know their information would be used. PM me for individual data. If all agree, I can include the Excel file, somehow. John Hawrylak Woodstown NJ -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at https://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.