This sounds pretty big, what do you think?

NEW YORK (Reuters) - After a decade of wide-leg pants and skinny tops, jeans are getting skinnier and are being paired with wider and longer tops.

The new look could boost sales for clothing retailers that roll out styles at the right time, but companies that change their inventory too rapidly or wait too long could be stranded.

"Fashion is usually a three-year cycle, but this is a major one -- it's a silhouette change that happens only every 10 years," said analyst Christine Chen, who follows apparel companies for Pacific Growth Equities in San Francisco.

Overall, the outline of women's clothing is reversing to an upside-down triangle, characterized by larger tops and narrower bottoms. Clothes overall are becoming less flashy, with details like darts, stitching and pleats replacing sequins and embroidery.

Companies ranging from women's career dresser AnnTaylor Stores Corp. (NYSE:ANN - news) to teen retailer Abercrombie & Fitch Co. (NYSE:ANF - news) to casual clothing stalwart Gap (NYSE:GPS - news) are rushing to get the newest shapes into shops.

But risks lurk, even with such a clear fashion shift. Companies that change their inventory too quickly risk alienating customers who have a preferred look, or those who are waiting to update their wardrobe until they have a clear sense of the styles.

And if companies wait too long to bring out the newest shapes, "you can miss the boat and be sunk," said CL King & Associates analyst Mark Montagna.

Montagna, along with other financial advisers and fund managers, expects teen retailers to be the most successful sellers of the new look.

"Newness in fashion is always good and in the near term, it's really good for the teen retailers. It gets the teens to shop," Chen said, noting that the younger generation looks better in leg-hugging pants, and that students will be anxious to get the latest styles for school.

Chen said she hadn't yet seen trendy young-adult retailer Urban Outfitters Inc. (Nasdaq:URBN - news) stocking the latest styles, which could prove troublesome for its summer sales, but she expected Gap, Abercrombie and Bebe Stores Inc. (Nasdaq:BEBE - news) to be on top of the trends.

The outlook is more uncertain for companies that cater to older women, such as Chico's FAS Inc. (NYSE:CHS - news) , which is known for its clothing for women over 35, classic apparel retailer Talbots Inc. (NYSE:TLB - news) and AnnTaylor.

"Talbots already has the right look since we're going to an unembellished style," said Marion Schultheis, who manages a portfolio of retail stocks for J.W. Seligman & Co. "And Chico's never got too wide (with their pant legs)."

But, she added, women are more cautious about spending on the latest fads, tending to wait until they see what becomes widely popular. That could mean women's retailers won't see the dramatic fall burst in sales that teen retailers will likely enjoy.

Schultheis also noted slumping May sales at Limited Brands Inc.'s (NYSE:LTD - news) Express chain, saying the company had likely stocked too many straight-legged jeans before consumers were ready for the look.

"Express got into skinny jeans first and look at their comps," she said, saying she'd counted on Limited shares rising due to their early fashion endeavors, and been burned.

Kurt Barnard, a long-time industry watcher who now heads his own industry forecasting group, warned that any bursts in sales and profits could be short-lived, even for the winners.

"Teen customers belong to a certain breed which is completely unpredictable," said Barnard, the head of Retail Forecasting Group. "Today you may find a company that is wallowing in sales and tomorrow those very same customers won't remember a store exists."