The fastest way to reach the site is email. For anything wrong with a number on a page — a length that does not match its source, a chart row that looks off — the report-an-error route gets it fixed fastest.
Email ianwelkins@gmail.com for anything about the site: a fitting question the pages did not answer, a source you think we should be using, or a clubmaker standard you believe is published differently somewhere. Mail is read by the person who maintains the calculators, not a support desk.
If a specific number on a specific page looks wrong, use the Report an Error page instead of general email. Error reports go into the corrections queue with the page attached, get checked against the published source, and — when the report is right — the page is fixed and the correction is visible in the site's next update. Every calculator on the site carries the same link in its footer for exactly this purpose.
A report that includes the page, the club, your measurements and the result you expected can usually be verified the same day. A report that just says 'the 7-iron number is wrong' has to wait for the follow-up questions.
Questions get an answer by email where an answer exists. Error reports get checked whether or not they get a reply — if you reported a number and it changes on the page, that was your report working. We do not send newsletters, marketing mail or anything else to addresses that contact us; your email is used to reply to you and for nothing else.