Originally Posted by
Biker Pete
I haven’t tried the RH calculator…..thanks for the info!
I have used Silca and SRAM and find them to be within about 2psi for the rear tire, SRAM being lower. And this is with using the actual measured width for Silca. For example I use 28mm tires, SRAM asks for that value (and the inner rim width) and when inflated the tires actually measure 29mm on my wheels which, if you input 28 vs 29mm in the Silca calculator, makes a significant difference in the calculated pressure. Also, SRAM always has a greater difference between front and rear tires than Silca.
I also have looked closely at the info on rollingresistance.com……so much data to digest in this ‘modern era’ of cycling……I love it!!!
Never liked the SRAM calculator, because it is inferring how wide your tires will be for a given rim width, even though it's quite known that different manufacturers nominally label their tire sizes differently versus how they actually inflate. It also only has 2 road surfaces to choose from -- Dry or Wet. Nothing to do with actual texture -- eg. rocky, smooth, dirt, etc. And then of course, since they're heavily invested in selling the hookless variety of wheel through Zipp, I expect their bias on PSI recommendations is always going to be on the low side in order to satisfy the marketing side of their business.
For any calculator, what none of them seem to ask for is the inflated height as well. Even sites like BicycleRollingResistance, will show the inflated height as well as width. I presume a taller inflated height means more air volume than a lesser height (for an equivalent inflated width, and there are sometimes fairly significant differences between tire brands on inflated height.