The Grand to Grand Ultra takes place in the high desert of the Colorado Plateau in the USA. The course, therefore, takes place in the altitude range of approximately 5000’ (1524m) to almost 8,700’ (2652m). Competitors can, therefore, expect to experience a large temperature range each day from a high of 30C (86F) during the day to lows overnight of 8C (46F) or lower. In fact, at the final camp at an altitude of around 7,000’ (2,134m), the temperature can drop overnight to below 0C (32F).
Given the unfamiliarity by most people with sleeping bag temperature limits, the following is a detailed explanation relating to the acceptability of sleeping bags (or quilts) for G2G. We do not wish to dictate specific brands of equipment for your use and we have found that many people have personal preferences. Accordingly, it is your responsibility to obtain appropriate equipment for a successful race.
Some technical stuff
Before asking us or the G2G/M2M Facebook Group if a certain bag is acceptable, please look for an EN13537 rating. This is a standard test method developed in Europe to allow comparison between sleeping bags and almost all manufacturers use this rating system. You should be aware that this is not a hard and fast evaluation of how “warm” a bag is going to be – it is just a guide. We will accept any bag that has an extreme rating of 0° C (32°F). It is however STRONGLY recommended that sleeping bags with a lower limit or better still a comfort rating of 0° C (32°F) be utilized for this event.
The following description of the EN13537 standard highlights the rationale behind recommending sleeping bags with a lower limit or comfort rating of 0° C (32°F), as opposed to an extreme rating. Your metabolism will be severely stressed during this event and on cold nights you may struggle to keep warm. Poor sleep will impede your recovery, as you will burn more calories to stay warm. It is better to carry the additional weight of an appropriate sleeping bag under these circumstances.
The EN13537 standard requires testing using an instrumented thermal mannequin to simulate a “standard man” and “standard woman”. A “standard man” is assumed to be 25 years old, 1.73 m tall (5’ 6”) and weighing 73 kg (160 lb). A “standard woman” is assumed to be 25 years old, 1.6 m tall (5’ 2”) meters tall and weighing 60 kg (132 lb). From this testing four temperature ratings are determined. These ratings are taken assuming that the subject is using a sleeping pad, tent and is wearing one base layer of thermal underwear.
- Upper Limit — the temperature at which a standard male can sleep without excessive perspiration. It is established with the hood and zippers open and with the arms outside of the bag.
- Comfort — the temperature at which a standard female can expect to sleep comfortably in a relaxed position.
- Lower Limit — the temperature at which a standard male can sleep for eight hours in a curled position without waking.
- Extreme — the minimum temperature at which a standard female can remain for six hours without risk of death from hypothermia although frostbite is still possible.
As you can deduce from the definition of these ratings above, an Extreme rating is associated with survival situations and is not the rating that is advised for use by competitors when deciding on their choice of sleeping bag.
Insufficient manufacturer specs
Some manufacturers may only provide a comfort and lower limit for their products. This has some risk associated with it. The lower limit quoted maybe an EN13537 lower limit or it may be an extreme limit. Under these circumstances, it may be better to err on the warmer side and select a product based on the comfort limit.
Sleeping bags we can recommend
There is a large range of sleeping bags on the market and depending on which part of the world, in which you live. The choice can, therefore, be overwhelming. The following bags have worked well for competitors in the past. Please note that we are not sponsored by these companies and therefore do not have a conflict of interest.
- Yeti Passion 1
- Yeti Passion 3
- Western Mountaineering SummerLite
- Western Mountaineering MegaLite
- Enlightened Equipment Revelation
One final thing to note is that most modern race bags which have a down filling and which weigh between 14-16 oz (400-460 gm) should be sufficient. Sleeping bags weighing less than this should be scrutinized and are unlikely to be sufficient.
Good luck in your search!