Podcast: Play in new window | Download
Subscribe: Apple Podcasts | RSS
Above is Scott Quiring’s 29+ Rig
Fat-bike Radio – Fat Camp Show #4
In this episode Ken and Andy talk about Tire/Wheel Sizes and Tire/Rim Ratios. Learn about the hows, whats and whys of using different rim widths with various tire combos.
Show Notes:
Tire rolling resistance links:
- http://www.schwalbetires.com/wider_faster_page
- http://velonews.competitor.com/2014/12/bikes-and-tech/resistance-futile-tire-pressure-width-affect-rolling-resistance_355085
- http://www.bicyclerollingresistance.com/specials/tubeless-latex-butyl-tubes
- http://www.mtbonline.co.za/info/mtb-tyre-rolling-resistance.htm
“Tech Tuesday – Wider Rims Are Better and Why Tubeless Tires Burp Air” by Richard Cunningham
|
Traditional 2.25″ MTB Tire |
||||
| Rim width | Inner rim width | Tire Casing width | Ratio | |
| Mavic 717 | 22 | 17 | 57 | 3.35 |
| Stans Crest | 24.4 | 21 | 57 | 2.71 |
| Stans Flow EX | 29.1 | 25.5 | 57 | 2.24 |
| 35mm rim | 35 | 30 | 57 | 1.90 |
|
Racing Ralph 2.4″ |
||||
| Rim width | Inner rim width | Tire Casing width | Ratio | |
| Stans Crest | 24.4 | 21 | 61 | 2.90 |
| Stans Flow EX | 29.1 | 25.5 | 61 | 2.39 |
| 35mm rim | 35 | 30 | 62 | 2.07 |
| Velocity Dually | 45 | 39 | 63 | 1.62 |
| 50mm rim | 50 | 45 | 66 | 1.47 |
|
Surly Knard 29×3 |
||||
| Rim width | Inner rim width | Tire Casing width | Ratio | |
| Stans Crest | 24.4 | 21 | 69.6 | 3.31 |
| Stans Flow EX | 29.1 | 25.5 | 71 | 2.78 |
| 35mm rim | 35 | 30 | 72.6 | 2.42 |
| Velocity Dually | 45 | 39 | 74 | 1.90 |
| 50mm rim | 50 | 45 | 75.8 | 1.68 |
|
Tire: 3.8″ Nate |
||||
| Rim width | Inner rim width | Tire Casing width | Ratio | |
| Clownshoe | 105 | 99 | 108 | 1.09 |
| Darryl | 82 | 76 | 103 | 1.36 |
| Marge Lite | 65 | 59 | 95 | 1.61 |
| Velocity Dually | 45 | 39 | 90 | 2.31 |
|
4.8 Bud/Lou |
||||
| Rim width | Inner rim width | Tire Casing width | Ratio | |
| Clownshoe | 105 | 99 | 119 | 1.20 |
| Darryl | 82 | 76 | 113 | 1.49 |
| Marge Lite | 65 | 59 | 105 | 1.78 |
| Velocity Dually | 45 | 39 | 95 | 2.44 |
Thankfully, my bikes tires burp from time to time, as opposed to tire farts..O.o
Great show! I’ve listened to all 4 fat camp shows and have learned a lot. Ken does a great job of dumbing down all the lingo and terminology for the laymen. Andy helps in this big time, when the bike geekness gets to deep he reals it back in. Fat shout out to Fat Camp. Greatly appreciate the free continuing education.
So the lower the ratio the better the rolling resistance?
Thanks for the reference charts! This is another reason I’ve been adimate in the replies, here, at Fat-Bike.com about posting flat casing widths (in addition to flat tread widths). My calculations show that taking the flat casing width and multiplying by 31% (an odd number, I know) produces the optimized rim width (or, conversely, dividing rim width by 31% produces the optimal tire casing)! The idea is to get the center of the circle produced by the tire in cross-section to, also, be centered on the rim producing the most stable tire averaged across all metrics.