Thunderbolts Guide: Gravel Bike Gear Selection
Photos: Ready Aim MediaEnsuring your bike is equipped with the right gearing is essential for conquering the challenges of the Thunderbolts Adventure. With nearly 5,000 meters of elevation gain over the weekend, including an 18km ascent on day one to the top of Barrington Tops, having the appropriate gearing will not only help conserve your energy but also minimise the need for walking. Many of the gradients encountered during Thunderbolts range from 12-15%, and when factoring in the additional weight of bikepacking gear, the importance of optimal gearing becomes even more apparent!
First and foremost, it's crucial to acknowledge that this isn’t a professional race (and you’re not a professional!). Instead of fixating on top-end speed, prioritise selecting gears that facilitate climbing. Remember you’ll be riding with a loaded bike and you won't be pedaling downhill (because of blind corners, water bars, erosion, cattle grids, oncoming cars, narrow dirt roads etc.), so there's no need to fret over high-end gear ratios. A key metric to consider is the gear ratio.
From our point of view, the magic ratio is 0.8
This figure is calculated by dividing the number of teeth on your front chainring by those on your rear cassette. For example, if your chainring has 40 teeth and the largest cog on your cassette has 50 teeth, the ratio would be 0.8. The tooth count is typically etched onto the chainring and cassette cogs but if you can’t find this you can manually count the teeth if necessary.
A ratio of 1 is the minimum we recommend for Thunderbolts and going lower than 0.8 is often advisable depending on your set up. Comments from previous TA riders on our Facebook Discussion page support this:
Joe: 0.9 “suffered like a dog”
Aengus: 0.94 “it wasn’t enough”
Leah: 0.68 on a MTB “No problem riding up the hills with a good fitness level.”
Scott: 0.9 “sufficient.. Made sure I was fit enough”
Matt: 0.8 “seems ridiculous when you first put it on, but I use it a lot.”
Stuart: 0.95 “It wasn’t low enough”
Special shout out to Nick who rode it on a single speed with a ratio of 1.6… We’re still not quite sure how he did it!
Considerations such as crank length, wheel size (700 vs. 650), and tyre choice also impact effective gearing. While online calculators exist for a detailed analysis, aiming for a ratio close to 0.8 based on your easiest gear combination is the most practical approach at this level!
Opting for a 1x MTB gearing system provides a range of options with a larger ratio.
Both Shimano and SRAM offer 1x groupsets paired with wide-range cassettes, offering versatility for varied terrain. For riders with 2x 11 or 10-speed setups, a product like the Goat Link can expand cassette options without the need for a complete groupset overhaul.
In conclusion, gearing plays a pivotal role in navigating Thunderbolts Adventure. Whether opting for a 1x setup or enhancing existing configurations with aftermarket solutions like the Goat Link, prioritising gear ratios conducive to climbing will strongly enhance your riding experience!
