All About Stone Grinding
Stone grinding isn't just for racers; having a good grind will help anyone get the most out of their skis!
Stone grinding flattens the ski base, removes burnt, and damaged base material and creates an important structure pattern. Bottom line, grinding makes your skis faster and easier to wax when done well. Factors you need to consider when stone grinding your skis are grind quality and how to choose structure patterns to optimize your skis’ performance.
How is it's Done
Stone grinding is a labor-intensive process, so skis are done in batches; weekly during the ski season and less often in the off-season. Once the process has started, each batch is typically completed in 4-7 business days.
The first step in the grinding process is flattening the base each individual ski. As skis age and are subjected to the heat of a wax iron and pressure of the wax scraper, bases tend to become rounded or concave. Skis are passed multiple times through the grinding machine; in some cases, a sharp metal scraper (in expert hands) is used to remove some base material, expediting the flattening process.
Once the entire batch has perfectly flat bases, skis are passed through the grinding machine several more times to polish the base material in order to prepare the ski to receive the structure ordered by the customer.
Now flattened and polished, the ski is passed once or multiple times through the grinder to apply the final structure. This step requires a great deal of experience, a steady hand, and expert eye to ensure that there are no flaws in the structure.
Finally, the skis receive a post-grind treatment to ensure they're ready to ski. At this point, we recommend any newly-ground ski receive a hotbox treatment as all of the wax-saturated base material has been removed by the grinding process.
The quality of a stone grind directly corresponds to performance. Producing high-quality grinds that yield the fastest skis requires advanced machinery and highly skilled operators. The people running the process must have a keen eye for grind quality as they manage the many variables that influence production on the machine. Experience, patience, and ability are all required to make high-quality grinds consistently.
BNS uses cross-country-specific machines that leave bases clean and hair-free, reducing post-grind base prep and giving you fast skis almost immediately. These machines are numerically controlled, which means that the diamond cutting system and grinding wheel are digitally controlled and can give us highly precise, repeatable grinds. Our machine avoids the burning, smearing and overly-aggressive structure we see in a lot of skis that are brought to us from other grinders.
Choosing the Right Structure
Snow varies widely in moisture content and snow crystal type, and ski performance corresponds directly to how well a stone grind pattern manages these factors. Some stone grinds have very broad ranges and handle a wide variety of conditions well, while others are superb in a very limited set of conditions and not very good in most others. The grinds you choose to put on your skis should depend on how many pairs of skis you have in your “fleet” and the conditions you expect to encounter most often.
Since ski quality itself is a dominant factor in performance, for most people, the best setup is 1–3 pairs of high-quality skis with broad-range grinds that put the best skis in the race more often. However, many high-level competitors have 4–6+ pairs of skis to be able to handle all snow conditions.
Choosing which grind to put on your skis should not be dif cult. The first step is to identify the characteristics of the ski itself – stiffness, camber shape and flex pattern. Often these characteristics determine the conditions in which the ski will be best.
Race Day Decisions
When it comes to choosing the right ski for training or racing, you may have to choose not only between skis but also grinds. Keep in mind:
- The fastest grind is the one that performs the best over the ENTIRE course. Course conditions often vary widely, so it is important to nd the grind that works for all of the conditions you will encounter. For example, a grind might excel in the glazed stadium area where many people have skied, but 90% of the course may be on newer, dryer snow out in the woods. A better choice would be a grind that handles the glaze but is also fast in the newer, dryer snow.
- Test skis/grinds against each other leading up to races if possible. Zero out two pairs by preparing (waxing) them the same way and testing them against each other to determine which grind is working best. Glide testing, as well as field testing (skiing with one ski each from two different pairs), are great ways to determine what is working best.
- On race day, use your knowledge of each grind’s strengths and weaknesses when making your choice. For example, if two grinds are testing the same, but conditions are warming, choose the warmer grind, or if snowfall is threatening, pick a new snow grind.
BNS Grind System
The BNS grind naming system simplifies grind selection. The system is easy: Each name starts with “S” or “C” to designate skate/classic. Two numbers follow, separated by a decimal point. The first digit corresponds to moisture and temperature range on a scale of 0 (cold/dry) to 5 (warm/wet). The second digit corresponds to snow type ranging from 0 (new/sharp) to 5 (transformed/rounded). These names bring clarity to each grind’s characteristics and also allow you to easily compare grinds relative to each other just by looking at their names.
We recommend our core grinds on the simple menu as the starting point for everyone. These broad-range structures provide a solid foundation to handle every condition, whether you have one pair of skis or 20. Our simple grind menu is based on how many pairs of skis you have in your fleet. Ninety-five percent of skiers have one, two or three pairs of skis, and we recommend different mixes of our core grinds based on how many skis you have to work with.
To find the right mix of grinds for your fleet, choose skate/classic and then pick the grinds that are highlighted for the number of pairs of skis you have. Every region has unique snow conditions. Skiers in the dry Mountain West will want to adjust toward the colder end of the menu, while skiers in the Northwest and California should consider moving to the warmer end of the spectrum. We are always happy to consult with individuals and teams to make recommendations that keep your life simple but ensure you get the best we have to offer.
Simple Grind Menu
With more performance data on the S2.2 grind, it has made our core skate grind menu. We also moved our core grinds toward the finer end of the scale, providing broader-range solutions that can be modified by hand structure. Everyone from ski manufacturers to national teams seems to be migrating toward this approach, so we are confident that these new core grinds are the best choices. We have two other grinds that are almost in our skate core: For extreme cold, we recommend S0.3. For wet conditions, S4.2 is an excellent choice. For a racer in the Rockies, S0.3, S1.3, and S2.2 would be a great setup for three pairs of skis, while east- and west-coast skiers might go warmer with S1.3, S2.2 and S3.2/ S4.2.