Lawyer/triathlete Steve Lyons in his downtown apartment. A mural of the original view from his balcony (the construction of a new bulding has since blocked his view of the Custom House) is painted on his livingroom wall. One of his competiton bicycles is at right.

In Somerville, Ed Champy of Waypoint Development just built six town houses a mile from Davis Square. He lives in one and sold two that were listed for $649,000. He’s renting out the other three for $2,500 to $3,000 a month. Why not sell everything now? Because he’s optimistic Somerville prices will rise even higher, so he’s keeping units to sell later. “The real estate bubble will be for the developer building a mediocre product,” he says.

Stephen Lyons isn’t so upbeat. A partner at the Boston law firm of Klieman, Lyons, Schindler & Gross, he recently shopped for condos — and decided to keep renting a $2,500-a-month apartment at Devonshire, a downtown high-rise. The million-dollar condos he looked at “were beautiful places,” he said. “But the prices are completely out of touch with reality.”

Some real estate analysts agree that prices are so high there could be a “bubble” in the market, just waiting to pop.

But the conventional wisdom is that market fundamentals remain solid, and that price increases and sales will moderate but not collapse. Mortgage buyer Freddie Mac recently noted that there should be a mild, gradual increase in 30-year fixed-rate mortgage rates to about 6 percent by the end of the year. Those low mortgage rates could continue to sustain a brisk housing market and lead to even more home sales and construction records this year.

“Buyers still seem to be very positive about buying homes,” added Carolyn Chodat, broker/owner of Classic Properties in Medway. “We haven’t seen much of a slowdown.”

Mark Zandi, chief economist at economy.com, a forecasting firm, says prices have been appreciating so much, so fast, that it’s plausible they will start to flatten.

One reason housing prices have risen so high is that many consumers now think a house is a better investment than the stock market. Dollars shifting to the housing market helps keep demand strong and prices high. But Lyons, the recent condo shopper, thinks a “well managed investment portfolio” is a less risky bet. He gave two reasons for not buying a condo. First is his comfort level; a big mortgage on an overpriced condo is a recipe for sleepless nights, he said. The second reason?

“When bartenders and barbers are giving you real estate advice, it’s time to stay out of the market,” said Lyons, 51.

Demand nevertheless remains strong for city condos, partly because of demographics, said Kevin Ahearn, president of the brokerage Otis & Ahearn. Baby boomers are selling suburban houses to move to the city, and that empty-nester trend isn’t slowing down.

After the economy stalled in 2000, the Federal Reserve cut interest rates in a bid to jump-start growth. That set off a chain of events that resulted in an era of historically low mortgage rates. Low rates make it cheaper for home buyers to borrow money. As the economy improves and adds jobs, mortgage rates are expected to rise. There’s a perception rates won’t rise sharply until after Election Day — a perception encouraged by real estate agents, said economist Nicholas Perna.

“Realtors love to talk that way,” he said, disagreeing with their timing. “What it does is get buyers off their duffs.”

He believes rates — regardless of the election — will gradually rise about 1.25 percentage points above where they are today as the economy improves over the next year. Higher mortgage rates could price some buyers out of the market and soften the demand that helps keep prices so high. Conversely, an improving economy could mean more consumers with jobs and higher incomes — and more potential customers for new homes.

Earlier this month, Jeff Brody, 37, was in the process of buying a home near his in-laws, partly because it will result in a “great day-care situation,” he said. Meanwhile, he and his wife looked to sell their current home in Bedford for $489,900 on ListForLess.com, a do-it-yourself real estate web site. The couple decided to act quickly so they’ll have the best chance of getting a low rate on their new home, said Brody, a lawyer. Interest has been strong, he added, in their Bedford home.

“Thirty people showed up at our first open house,” he said. “We feel this is a great time to put a house on the market.”

Eric Gibson, a salesman about to get married, was looking to close earlier this month on his first home purchase, a Framingham split-level for about $350,000.

“It’s a good investment,” said Gibson, 29. “I didn’t want to throw my money away on rent.” Low mortgage rates were a “driving factor” in the decision, he said; higher rates could put a purchase out of reach.

Thomas Kunz, chief executive of Century 21 Real Estate Corp., doesn’t expect the election to have a big impact on the housing market. Most people buy or sell homes because of a “life event” such as marriage, a new baby, or a divorce, he said. That equates to steady housing demand and is one reason why, Kunz said, “I don’t think you’re going to see a bubble.”

Margaret Carr, 53, recently sold her Revere condo. A certified public accountant, she got an unsolicited offer for just over double the $122,000 she paid for it 14 years ago. Investing money from the sale and renting an apartment, she’s taking a wait-and-see attitude toward the real estate market.

“We all know the market is cyclical,” said Carr. “We’re so far away from historical averages that things can’t continue at this pace.”

In a recent report, Harvard University’s Joint Center for Housing Studies concluded that signs point to “a soft landing” for the housing market, not a burst bubble — provided the economy doesn’t unexpectedly contract. However, the center’s director, Nicolas Retsinas, said “tiny bubbles” could emerge in some regional housing markets if there are “concentrated job losses.”