Marketing for a bike shop?

You need to start building out manufacturer pages, and then product landing pages When people are in "buying mode" they are looking specifically for what they want. " pinarello cadore " ( a bike frame ) as an example.

Adding value for this customer is content development... increasing the opportunity of thier customers to find them when they are making a purchase decision.

Does the shop have a google business listing? are they listed in Google map? are they in the 3 packs anywhere? this is also something that may need to be targeted.

Content building and citation building.

What about localized SEO and such. Yelp, Google maps, tie in a review page. Make sure they are responding to customer complaints, wherever people tend to do most of their complaining.

Well, if I'm reading this correctly, you got yourself a sale and thus, a client.
Congratulations!

"What can I do to add value?"

How did you get the sale that led to the person becoming a client? Was no product or service discussed? If not, how did you determine what to charge the client?

Missing something here.

What about some offline marketing activities? For example, printed products, promotional items.

Any kind of activities that generate interest in the shop / brand and products they sell. It can be anything from standing outside telling people passing by on the street, to hand flyers, brochures, cross promotions at fitness events / conventions, getting them talked about on the radio, in print, online, etc.
Low cost, give away promotional items such as stickers, key chains and someone else suggested lapel pins are a great way to get the name out htere. You want to figure out who their ideal customer is and how to reach them, pull them in , build relationships with them and get their info so you can maitain those connections. People are paying you to make things happen (generate interest, enthusiam, curiostiy, excitement, etc) for them.
If you do not know much about any of the strategies already (and it sounds like you might not) you are fighting an uphill battle. But that doesn't mean you can't win!
Get the book Guerrilla Marketing and or do research for case studies of the most successful examples of that.

Good luck and make things happen!

Citations + reviews to the GMB page, NAP 100% consistent across all citations/listings, FB is not the be all and end all of social media, Twitter, Reditt, Instagram, YT to name just a few.

Hello,I suggest that marketing is an umbrella to covers advertising ,public relation,promotion and sales.These are many types of marketing used in business.you can online marketing to increase our business like a SEO,SMO&more.
Thanks

I highly recommend placing a display ad in a local newspaper or advertising circulation that is sent out to his community. An ad in a local publication that everyone in his area receives will be the best money he can spend advertising.

Start promoting your product it will automatically add value.

Wouldn't this be about offering $5 Spring tune-ups or hosting a bike show of new models or organizing a bike-a-thon for charity, things of that nature, all with the side result of getting bike buyers into the shop where they then maybe can be sold or upsold?