Here’s an article we wrote that fully describes their purpose

Laguna Coast Wilderness Park/Aliso and Wood Canyons Wilderness Park/Whiting Ranch Wilderness Park
May, 2016 – February, 2017

The Laguna Canyon Foundation (LCF) and the Orange County Parks, in partnership with the SHARE Mountain Bike Club (the local Orange County IMBA Chapter) and the Think MTB Mountain Bike Club, have recently introduced a Bike Bell Program in a few of the wilderness areas in Orange County that are regularly frequented by mountain bikers, hikers and equestrians.  The parks that currently have an established bike bell program are:  Laguna Coast Wilderness Park (Nix Nature Center and the Willow Parking Lot), Aliso Wood and Canyons Wilderness Park (Ranger Station), and Whiting Ranch Wilderness Park (Borrego Entrance).  The trails in these parks have seen a significant increase in usage over the past years, especially by mountain bikers and hikers.  Because of this increase, it is common for the trail users to come into contact with each other; this can result in the need to share the same section of the trail.  The established trail etiquette rules state that all trail users should share the trail in a courteous manner.  The trail etiquette rules also indicate that there is a hierarchy relative to sharing the trail:  hikers need to yield to equestrians, and mountain bikers need to yield to both equestrians and hikers.

Because of the trail etiquette rules, and the fact that mountain bikers can come upon the other trail users rather quickly, it is necessary for the bikers to alert the other trail users of their presence and indicate if they would like to pass the other trail user.  The mountain biker can use the standard verbal alert by saying “on your left” and then wait for the other trail user to acknowledge him/her before passing.

Another increasingly popular method for mountain bikers to alert other trail users is by ringing a bell that is attached to the handlebars of their bikes.  There are two main types of bells being used by mountain bikers — an “active” bell that the biker needs to push the button to ring the bell, and a “passive” bell (cow or bear bell) that rings on its own.  One type of passive bell that is often used is the type that can be silenced via putting a magnet on the bottom (the magnet is attached to a strap that can be easily put on and off while riding).  The riders are supposed to use their bells mainly in situations where they are going into “blind” corners and while descending rapidly on a hill.  When in an area where they are going slowly and/or uphill and can see clearly, the riders do not typically need to use their bells as much.

In order to establish the Bike Bell Programs for the LCF and OC Parks, we gathered information from other bike bell programs that have already been up and running in San Diego, Los Angeles, San Luis Obispo, Santa Barbara, and Sedona, AZ.  Even though these areas have slightly different signage and bike bell boxes for distribution of the bells, they all have the same goals — to help with trail conflicts among users, to provide for a safer trail experience, and for educating the trail users on proper trail etiquette.

Both the LCF and the OC Parks made the decision to introduce their bike bell programs by distributing the bells to the mountain bikers via volunteers that sit at a table at the main entrances to the parks and hand out the bells.  The volunteers are representatives from the OC Parks staff (park rangers), SHARE and Think MTB Clubs, and the LCF Wilderness Access Volunteers (WAVs).  The reasons for having volunteers initially distribute the bells were:  so that the table with the bells is visible to the bikers, so that the volunteers can talk to the bikers about the importance of taking and using a bell on the trails, and so the volunteers can gather feedback from the mountain bikers relative to their use of the bike bells.  The volunteers also ask for feedback from the hikers and equestrians regarding the bells – i.e., do they like hearing the bells on the trail, do they prefer hearing the bells versus the standard verbal warnings from the bikers, etc.  After establishment of the program, both the LCF and OC Parks have plans to mount the bike bell boxes and signage on permanent structures at the most used entrances to the parks so that the mountain bikers have continuous and easy access to the bells.  The following shows a few pictures of the volunteer table, the volunteers talking with the bikers about the bells, and a sample box that holds the two different kinds of bells – active and passive.

To date, the bike bells have been donated to the LCF and OC Parks/Whiting Ranch from both the SHARE Mountain Bike Club (the passive “bear” bells) and the Think MTB Club (ringer bells).  The SHARE MTB Club funded their bike bells via a grant from REI that was given to SHARE specifically for the bike bell program and also by using funds from SHARE’s general account that is replenished throughout the year by an annual fundraiser Poker Ride, by membership dues, and by individual donations to the Club.  The Think MTB Club funded their bike bells via individual Club member donations for the bike bells. As the bike bell program has expanded, the need for more bells has increased.  The bike bell program is set up such that the rider is instructed to take a bell and then return the bell to the bike bell box after his/her ride. However, this can be difficult if the rider does not return to the same spot that he/she got the bell.  For this reason, and in order to encourage the rider to keep using the bell on his/her future rides, the volunteers who are distributing the bike bells (and the signage that is on the bike bell boxes) mention to the riders that they can keep their bike bells.  The bells are provided to the rider at no cost; however, if the rider would like to donate to the bike bell program and help with the purchase of more bells, he/she can donate via the various groups’ websites listed on the bike bell box signs.

The information provided by the volunteers that have distributed the bike bells in all three wilderness parks has indicated that overall the Bike Bell Program has been received very well and the feedback from the mountain bikers and hikers (regarding the bikers using the bells) has been overwhelmingly positive.  The mountain bikers have been very receptive to not only taking and using a bell on their bikes, but also to the reasons why using the bike bell is important.  The bikers’ preferences regarding the type of bell they want to use is split fairly evenly between the two types of bells (active and passive).  The hikers have commented on how much they like hearing a bell to alert them that a mountain biker is approaching – they especially like the passive “bear” bell because it can be continuously heard from a distance and is softer in tone than the active “ringer” bell or a verbal alert from the rider.  The mountain bikers also like hearing the bells on the other bikes so they are alerted that a bike is present.  There have not been any equestrian riders to date to get feedback from, so we are not yet sure of how they feel about the bike bells.  Based upon past experiences with equestrians, the understanding is that the equestrians would like to hear a low volume warning prior to getting close to the horse; so a bike bell in the distance should be helpful to prevent startling the horse and rider.

As a result of the positive reception from the trail users, the SHARE MTB Club and the Think MTB Club have to date donated approximately 2,300 bells total to the LCF and OC Parks’ Bike Bell Programs. The distribution and use of this many bells will help provide trail users with a safer and more enjoyable experience.  In addition, the use of the bells will help foster an environment that encourages courtesy and sharing of the trail by all users.