If Sheldon Brown had been only an excellent bicycle mechanic, the esteem in which he was held, while great, could not have extended much beyond his native Massachusetts. But because of the selfless use to which he put the internet, regret at his death has been felt across the world.

His knowledge of bicycles, from a lifetime of riding them, taking them apart, fixing and modifying them, was encyclopaedic. For more than 20 years he earned a living from that knowledge with the spanners, screwdrivers and tyre levers of a succession of bicycle workshops around Boston, and he could probably have gone on doing so happily until retirement. Then, at 49, he found at his disposal an invention more powerful than anything in a mechanic’s toolbox. He quickly saw that the internet could make his expertise available not just to the customers of one bike shop, but to anyone who wanted it, anywhere. It turned out that a lot of people did. The website he built, sheldonbrown.com, has attracted millions.

Sheldon Christopher Brown was born in Boston in 1944. After his father’s death in an air crash when Brown was 9, the family settled in Marblehead, Massachusetts, and it was in the Marblehead town dump that his career in the bicycle business originated. During high school he built bikes out of parts scavenged from the dump and sold them. Like many in the 1960s he heeded Timothy Leary’s call to turn on, tune in and drop out, not staying long at college or in a series of jobs selling shoes and hi-fi, and driving taxis.

By 1972 bike repair was his career, and he set up the Boston Bicycle Repair Collective, a fellow founder member being Stan Kaplan, inventor of the Kryptonite bike lock. After, as he described it, being “purged by Maoists” from the collective, for a time Brown turned his dexterity to camera repair. But he went back to working on bicycles, and by the early 1980s, in a move towards his ultimate future, he was not just repairing bikes but writing about them.

His audience in specialist cyclists’ magazines, however, was necessarily limited. Then came the internet.

In 1990 Brown had joined Harris Cyclery, a shop a few minutes’ bike ride from his home in Newtonville, a Boston suburb, as a mechanic. As the internet developed, he became a contributor to cycling newsgroups, and in 1995 Aaron Harris, his employer, let him set up a website in association with the shop. Initially it was intended to sell specialist parts, but soon Brown took it far beyond that. “Aaron let me spread my wings,” Brown said in 2001.

The website certainly flew. Last year sheldonbrown.com had more than half a million visitors a month. They came for everything to do with bikes, from advice for timid beginners on how to mount a bike to instructions for the daring on how to build their own tandem. The site has a glossary of almost 1,000 terms from “A and B chainrings” to “Zzipper”.

If you couldn’t find what you needed on the website, you e-mailed and asked, and “captbike” usually replied the same day. Answering 200 e-mails most days, he was courteous and informative, but hadn’t time to be wordy. One correspondent, told that replacing his 20-tooth back gear with a 22-tooth would make climbing hills easier, asked how much. Back shot a classic captbike reply: “10%.”

Brown did not charge for access to the site or for his e-mail advice, but the site was a vindication of the internet freeware credo that putting up free content will bring its own reward. It brings in about half Harris’s business.

But sheldonbrown.com was, and is, about more than commerce. Nor is it just a compendium of technical information. It includes a blog that started before the term existed, recording the personality, the philosophy, the likes and dislikes, and above all the family life, of the man who built it. In 1979 Brown married Harriet Fell, who teaches at Northeastern University, Boston. A daughter was born in 1981, and a son in 1983. The blog records his devotion to them, his pride in their accomplishments, and such family adventures as touring in France on two tandems when the children were 6 and 8.

Given his lifelong delight in cycling, it was particularly cruel that in the past two years multiple sclerosis gradually robbed him of the ability to ride a two-wheeler. His response was characteristic — he got a recumbent tricycle and kept pedalling, still riding it to work until shortly before he died. And he wryly put a page titled “The Bright Side of MS” (easy parking with a disabled sticker, jumping airport security queues) on his website.

The response to his death has been a fitting combination of bicycles and the internet. From Melbourne to Missouri, cyclists have held or are planning memorial rides — co-ordinated, naturally, on the web. The London ride is on April 6.

Sheldon Brown, cyclist, was born on July 14, 1944. He died of a heart attack on February 3, 2008, aged 63