Rock 'n' roll bands are powerful yet fragile institutions. Whether they contain several major talents (the Beatles), or a lucky mix of minor ones (the Byrds), or even one overpowering leader (the Velvet Underground), the postsplit solo albums are almost always a disappointment.

Solo albums don't always mean the end of a band, of course. Sometimes they're just a busman's holiday, and sometimes the band muddles through without a recently departed member, even if that member was generally considered the leader. Mick Jagger's solo career, for example, may not mean the end of the Rolling Stones (though many observers insist it does); Jagger could regroup with the Stones, or they could even continue without him. The latter course seems to have worked for Pink Floyd, which is now proving quite successful without its former main songwriter, Roger Waters.

Mick Jagger: 'Primitive Cool' Few veteran rockers have juggled the conflicts between outlaw image and upscale life style more deftly than the Rolling Stones. They've become jet setters, tax exiles, middle-aged husbands and fathers, all the while managing to retain their bad-boy credibility. Jagger, with his expensive tastes and cafe'-society pals, has long been the band's principal liability in this regard. His solo work makes it clear (just in case it wasn't always) that without the aid of the Stones' genuine bad boy, Keith Richards, the singer's street-cred is at serious risk.

"I just don't do things by halves," boasts the first line of "Kow Tow," which opens Side 2 of Jagger's second solo album, "Primitive Cool" (Columbia OC 40919); he wants listeners to believe that as much as he wants to believe it himself. But "Cool" -- half produced by Jagger and Keith Diamond, half by Jagger and Eurythmic Dave Stewart -- is a classic "by halves" album: It features a panoply of session musicians (including guitarists as diverse as Jeff Beck, "Saturday Night Live" band leader G.E. Smith, Black Rock Coalition founder Vernon Reid and Tom Verlaine lieutenant Jimmy Ripp) and an anonymous, high-gloss sound that's closer to Michael Jackson's "Bad" than the Stones' "Exile on Main Street."

Musically, "Cool" is solid, but its sensibility is significantly off kilter. The problem is embodied by "Let's Work," the album's first single and its most melodically engaging song. "The world don't owe you," Mick scolds, "Ain't gonna cry for you/ If you're lazy." This is a curious sentiment for a rock 'n' roll song, but it might convince coming from an uptight pop puritan like David Byrne. From globe-trotting rock gentry like Jagger, though, it sounds hollow indeed; this could be an anthem for celebrities who've completely lost touch with how normal people live.

In the past, the Stones have erred on the side of sensationalism, but seldom flirted with sanctimony and sententiousness. "Primitive Cool" is both, and frequently. In the title song, Jagger willingly assumes the dubious role of the rock patriarch, asking himself questions such as "Did you walk cool in the '60s daddy?," "Did you fight in the war?," "Was it all just crazy fashion?" (Mick's penetrating answer: "Oh yeah"), and -- cringe -- "Did you know Dr. King? Was he ever so humble?"

A few other songs -- "Throwaway," "Say You Will," "Kow Tow," the sub-Stonesy "Shoot Off Your Mouth" -- swagger agreeably, but the album is defined by its major thematic miscalculations: "Let's Work" and the overlong ballads that close each side, "Primitive Cool" and "War Baby." The last is Jagger in full Polonius mode: "Why can't we walk this road together," he asks, "And keep our children safe and sure." That faint sound you might hear in the background is Keith Richards, guffawing uncontrollably on the other side of the Atlantic.

Pink Floyd: 'A Momentary Lapse of Reason' While Jagger blows a 25-year reputation for keeping his tongue in cheek, former Pink Floyd bassist Roger Waters is carrying on that band's tradition with his "Radio K.A.O.S." album and tour. So, too, are Pink Floyd's three other members, guitarist David Gilmour, drummer Nick Mason and keyboardist Richard Wright, with their new "A Momentary Lapse of Reason" (Columbia OC 40599).

Oddly enough, Pink Floyd (which performs at Capital Centre Oct. 19-22) has survived being abandoned by its leader once before. Two decades ago its exceptionally influential songwriter Syd Barrett left, making a pair of solo albums before ending up in an asylum. The band shifted its style radically then, indulging in lengthy electronic freakouts before hitting on the gloomy rock-operatic sound that has made its "Dark Side of the Moon" the longest-running album on the Billboard charts (697 weeks and holding).

Previous Floyd epics such as "The Wall" consisted chiefly of drawn-out, portentous overtures and interludes separating one or two identifiable songs. "Lapse" follows this formula, except that Gilmour, Floyd's new principal composer, forgot to provide the songs.

Well, he didn't exactly forget. Would-be anthems such as "Dogs of War" (more apocalyptic than Jagger's earnest "War Baby," but just as shallow) and "Sorrow" are clearly intended to play the cathartic role of old Waters-penned rousers such as "Another Brick in the Wall." But except for the pretty "On the Turning Away" (its melody a near-ringer for the Scottish folk tune "Wild Mountain Thyme"), "Lapse" is all massed chords, ponderous thumps and thick echo.

This solemn, despairing music -- empty as it may seem to the uninitiated -- apparently sounds authentic to Floyd fans; "Lapse" is already a Top 20 record. Assuming Waters' pending lawsuit doesn't prevent them from continuing to use the name, Gilmour and company may keep Pink Floyd lumbering along without Waters as long as they have already without Barrett.