Bolder was active in his local R&B scene in the mid 1960s.
With The Rats, he played whith Mick Ronson (26 May 1946 – 29 April 1993) (lead guitar).

In 1971 he replaced Tony Visconti in David Bowie's backing band, known as the Spiders from Mars.
Bolder's bass (and occasional trumpet) work appeared on the studio albums Hunky Dory (1971),
The Rise and Fall of Ziggy Stardust and the Spiders from Mars (1972), Aladdin Sane (1973), and Pin Ups. (1973)

In 1976 Bolder was recruited to join Uriah Heep, replacing John Wetton.

The attempt to put a new line-up together temporarily stalled and Bolder, accepted an offer in 1981 to join
Wishbone Ash. Bolder had, coincidentally, again replaced John Wetton, becoming The Ash's bass player for
their album Twin Barrels Burning (1982).
In 1983 he returned to the rhythm section with Uriah Heep, playing on the Head First tour (although Bob Daisley
played on the album).

As well as his usual bass-playing and backing vocal  duties, Bolder also produced Heep's (1991) abum Different
World. He sang lead on "Fear Of Falling", one of the tracks he had written  for Sea Of Light (1995).
(Although credited on the album cover  with lead vocals on "It Ain't Easy", last track on Conquest ,
it is not Bolder singing).

He remains a member of Uriah Heep, and has also played with Cybernauts.