Do you suggest I delete the text? Or can I define it as tags while hiding it from the page?
The proper way to do this is to include it in a META tag, like this:
<meta name="keywords" content="bike in NYC Traffic, Bicycle safety, Safe Biking Tips, New York City, #BikeNYC, Riding in Traffic, Traffic Safety, LCI, League of American Bicyclists, Vehicular Cycling, Stress Free Cycling in NYC, Private Bike Lessons, Learn to Ride a Bike, Bicycle Wellness Seminar, #CitiBikeNYC, Traffic Skills, Personal Bike Training, Private Lessons, Beginner's Bike Safety ">
It has to be enclosed in an HTML tag of some sort. You can't just add plain English.
But, most search engines disregard this use of keywords. You can read about it here:
They tend to look at keywords in page text, rather than what's hidden in your code, because that's what your visitors see. The key is to have just the right amount: not too many and not too few. A lot of us use the SEO by Yoast plugin, which is really good at analyzing that for you.