There must be lots of ways to recruit volunteers.  This is so important that I could go on for hours about this.  Here are a few thoughts off the top of my head, regarding how to find, recruit and retain volunteers:

LOCAL BIKE ENTHUSIASTS

The lowest hanging fruit is from bicycle enthusiasts.  Typically your existing volunteer base will include a number of people who belong to local bike clubs or bike advocacy groups.  Bicycle enthusiasts are the most likely to already have bike repair skills.  The ones who don't already have them are usually VERY receptive to any opportunity to gain knowledge and practice, under the guidance of your experienced volunteers.

Get your experienced volunteers to spread the word (either by mouth or through bike club newsletters) that you are looking for new volunteers.  Be sure to explain your mission, and what skills are required of volunteers.  If you will teach new volunteers everything that they need to know (which you should), be sure to say this.

CORPORATE VOLUNTEERS

Another possible way to recruit is through larger local corporations.  Believe it or not, many local companies have a desire to do good for their local community by encouraging their employees to volunteer at non-profit organizations.  They may allow groups of employees to volunteer their labor during work hours.  Some of them may additionally donate to your nonprofit shop a few hundred dollars per session, for you to lead these volunteer sessions.  The nicest of these also provide catered lunches for their employees, plus a few of your own staff that lead the events.

Why would a company *pay* for you to provide a volunteer opportunity?  Reasons go far beyond supporting the local community.  The company may gain a public relations benefit if word gets out that they are paying for their employees to volunteer during work hours.  The group may see it as a valuable team-building activity that benefits the company, as employees are able to interact and get to know one another outside of the work environment.

How do you find such corporate gigs?  If none of your current volunteers works at a nearby large-ish employer, ask around among your cyclist community.  You could also try cold-calling your local employers and try to talk to someone in human resources or community relations, paying special attention to those companies that make donations to the community, sponsor local sports teams, or run advertising on the tv, radio, billboards or a local newspaper.  If a company has never sponsored such events, it might be a good opportunity to stress the benefits to the employer that result from sending their employees to your volunteer events.

As you reach out to corporations, it is important to have structured and specific activities in mind.  For example, "repairing bicycles to give to local children in need" always sounds a lot better than "cleaning up and reorganizing the shop" or repairing bikes to sell.

If you doubt me, and are skeptical of this advice, I urge you to ask some older people, particularly those who have worked in management at your local large companies.  Large companies do want to build a positive image in their communities, and some will want to support you by sending employees your way as volunteers.

LOCAL VOLUNTEER GROUPS

We just talked about the corporate world.  Where I live there are also plenty of *community* organizations that want to send volunteers to worthy non-profits.  These could be church groups, adult service clubs (e.g. Rotary), Boy Scouts looking for service projects, or high school kids who may need to fulfill a community service requirement.  Find out if any such volunteer pools are in your area.

In many locations there are also organizations whose sole purpose is to match up volunteers with volunteer opportunities.  When I googled "group connecting volunteers with nonprofits" I got back a list of such organizations, including VolunteerMatch, Taproot, Catchfire, and Goodera.

In my area we have a local VA hospital.  Someone organized a group of veterans who use the VA hospital, to come and volunteer at our nonprofit shop.  Your shop might wish to return the favor to them by supplying the VA with low-cost repaired bicycles to give to patients who are rehabilitating an injury.  You can create a virtuous cycle!

Think carefully about this next suggestion.  There may be convicted criminals needing to complete community service hours that were ordered as part of their sentencing.  You might well have concerns about violent offenders or thieves, but there might still be a class of offenders that you would be comfortable with, who deserve a chance to become productive volunteers and members of society.  At the same time, you need to balance a desire for volunteers against the possibility that convicted criminals might make your existing valued volunteers uneasy, and drive them away.  It might be hard to retain volunteers who are there because a judge is forcing them to be there.

PUBLICITY

There are doubtlessly people in your local community who would happily volunteer with you, if only they knew that you existed.  Consider doing something to raise your shop's profile.

For example, if you have a local Bike To Work Day, perhaps you can sponsor an Energizer station.  In advance of Bike To Work Day you could hold a free bike check and free minor repairs.  If your shop is out of the way, try enlisting local public libraries to provide space, advertising, and credibility: many libraries have an event calendar for lectures and activities on their premises.

Local newspapers may be willing to publicize your volunteer events in a community calendar.  Some experts say that you should write a press release and send it to your local newspapers.  Personally, when I asked a seasoned local news reporter, she told me not to bother writing a press release because any decent writer is going to want to interview you and write their own copy.  You could always ask each local newspaper how they would like to proceed.

If your shop doesn't already have a website and business cards, get them!  Nothing builds credibility more than being able to hand someone a business card that has your shop's contact information and a URL where people can go to for more information about who you are, your benefit to the community, and how they can help by donating labor, bikes, or money.

PREREQUISITES

Before you bring in a bunch of new volunteers, you need to have a few things in order.  Most importantly, you need trained volunteers to lead and train new volunteers through planned activites.  Generally, you also need structured programs, to help you pitch your volunteer opportunities to prospective client groups that could send volunteers to you.

One of the biggest challenges at my local community bike shop is not getting volunteers, but rather keeping them: very few new volunteers come back at all, let alone with any regularly.  A few years ago, at the Bike! Bike! in Los Angleles, there was an excellent session on volunteer retention.  My biggest takeaway is that people volunteer for various reasons.  People who come alone probably want to meet other like-minded people.  People who come from churches and service groups especially want to produce something tangible, such as several completed repair projects that will be donated back into the community.  Other people may want to learn and practice new skills, or share a rewarding activity with a family member.

It usually takes a concerted effort to greet new volunteers, make them feel welcome, teach them so they can feel productive, and meet their various needs for learning and accomplishment.  Please brief your existing volunteers who will be helping you to put on these new volunteer events.  Remember people's names.  When each new volunteer leaves, make sure to call them by name and tell them how much you enjoyed having them and you would love to have them return for the next volunteer activity.  As they leave, remind them of the date and time for this next volunteer session.  Have a sign-up list where you collect names, phone numbers, and email addresses, so that you can follow up with more words of thanks and notification about future volunteer events.

CONCLUDING THOUGHTS

There are plenty of things you can do to recruit and retain new volunteers.  These are just some methods that happen to work in my local community.  There are bound to be other things that work well in other places.  Please discuss and feel free to disagree.

The most critical overriding concern should be volunteer retention.  It's easy to get someone to come once, but what you really want are volunteers who come back again and again.  With some thought you can plan for this and improve your number of repeat volunteers.