I've read many tales of old favorite bicycles who have been given a new lease on life with fresh paints and all new components. After all, a frame should last virtually forever, shouldn't it? The problem often lies in the components - they get tired and wear out, especially under the stress of touring. Many cyclists are able to do their own mechanical work. Others, like me, rely on professionals. My touring bike, center in the photo below, has served me well for ten years. It has been serviced often and had parts replaced as needed. I have two identical touring bikes (identical in all but color). One of them always seems to be in the shop, needing some sort of work. It does get tiresome. Jacinto was often after me to 'just replace that bike already!'.

A trike riding friend is planning a 9,000 mile tour on her ten year old trike. It has been suggested she would be better off starting such a journey on a new trike. I can see the wisdom in that statement.

How many bicycle shop stops is reasonable on tour? At what point do you decide your old friend should be replaced with a less likely to need repaired model? It's hard, leaving an old friend behind when leaving on a new adventure. 

I hope that RacPat contribute to this thread, they seem to be riding some nice old frames.

The advent of disc  brakes may eventually force a change as quality rims with braking tracks are getting hard to find.

It has been suggested that $himano may be considering discontinuing cable shifting on the upper level group sets and forcing users to go to the more expensive electronic shifting.

With the exception of Serenity, the newest bike in my fleet is 13 years old.  I've never gotten rid of a bike because it was "worn out" or "too old to bother fixing".  Individual components, yes, and particularly wheels.  I've literally worn through the rims on at least two bikes, but new wheels are cheaper than a new bike.  (They also afford an opportunity to refresh and improve the hub quality in said wheels, should you desire to do so.)

As Mike Ayling said, the change from rim to disc brakes may force a change if quality rims designed for rim brakes become unobtainable but I have a hard time imagining that will happen any time soon.  I could easily enough be wrong, though, as I do not have my finger on the pulse of current trends in the bike industry.

Chains, chain rings, cassettes, brake pads, cables, etc. are normal wear items and need to be refreshed at intervals (based on miles traveled rather than the mere passage of time).

Doing all you can ahead of a tour to ensure that the maintenance has been done is the best way I know of to avoid being forced to find a shop while on tour.  Things happen, of course, and not everything can be anticipated.  A broken derailleur or derailleur hanger will put your bike in the shop, for example, and there's not much you can do beforehand to prevent such a thing.  But those are externally-triggered and relatively uncommon events and just as likely to happen to a brand new bike as to an old trusty mount, I think.

"It has been suggested that $himano may be considering discontinuing cable shifting on the upper level group sets and forcing users to go to the more expensive electronic shifting."

It's been my experience over the years that Shimano (or ShimaNO) as I call them are particularly aggressive when it comes to planned obsolescence.  They seem to have a special talent for discontinuing one design in favor of something else, year in and year out, and for ensuring that what's new is fundamentally incompatible with all previous issues.

That said, so long as the quality of their middle tier (105, Tiagra, Ultegra, Deore, Deore XT) components remains good I will not completely shun them just yet.  I think the only ShimaNO parts on my newest bike are the bar end shift levers, and I'm not even certain they are ShimaNO.  Everything else came from other manufacturers; this was as much the result of the choices the builder made as it was my deliberate choosing but I'm pleased it worked out that way.  

None of my other bikes is a ShimaNO Free Zone; indeed a couple of them are almost entirely fitted with their parts

Many years ago, when I had my first recumbent, I wanted to completely refurbish the bike. I rode year round, commuting and touring. It had big miles on it, although I can't remember now what that was. The bike had served me well and I wanted to keep it fresh. I told John (shop owner), that I wanted to repaint the bike and replace all of the components. He started listing prices, and said it would be cheaper to buy a new bike! 

That slowed me down a little bit, but I did end up buying a new bike and selling the old one. I haven't done that again. I've been replacing parts as needed. The shifter of choice on my recumbent is a 9 speed grip shifter. Those are hard to come by now, but I just replaced one, and have another set saved. Looking for those shifters is part of what made Jacinto say I should get a new bike. Of course, those aren't the only shifters on the planet. The Phoenix has thumb shifters, which I quite like. 

It isn't quite the same, but similar, when owning a motor vehicle. There comes a time when dependability and cost of repairs is not worth while. My minivan is seven years old, it runs fine. It's excellent for hauling my long bicycle and other things. But, I am concerned about driving it across vast Navajo Nation back and forth to Tucson. Around town, or some place populated, I don't think twice. 

I think there comes a time in every vehicles life when it is relegated to around town status, from long haul status. It's not always obvious when that time comes.

I did retire my 1984 Trek 620 in 2006.  I was halfway through a trip down the Natchez Trace Parkway when the seat tube broke in two, at the dent / weak spot created 15 years earlier during a theft attempt.

By now it might've been relegated to "around town" status but perhaps not: the components were dead simple and (I think) still built to ISO standards.  I know at least some of them could still be sourced from FleaBay though they'd not likely be used and not NOS.

Our Bike Friday DoubleDay (recumbent tandem) has a now-impossible-to-find-at-any-price click box that connects a shifter to an internally geared rear hub; if that click box ever fails it'll spell the end of the wheel and probably the end of the bike's time with us.

On the other hand, since we only used that bike when on supported tandem tours in Europe, and since the people who organized the tours have stopped doing so, the day I have to make that decision is still an indefinitely long time in the future.

I agree with Keith Adams that a well maintained old bike has about the same failure rate as a new bike. Kelly's 10 year old touring bike is much better maintained than my 15 year old touring bike. Yet I almost never need to visit a bike shop during tours.

Generally, the wear-out failures are predictable and often have warning signs. Rim brakes have worn out 4 sets of rims in 15 years. Hubs have gone bad. A bottom bracket disintegrated. Replaced the rear 9-speed grip shifter twice. Plus countless chains, tires, cables, and brake pads.

I think it's a lot like buying a new car.  Most of the time folks don't really NEED a new car, but they rationalize that they do.  It's almost always more economical to keep the vehicle you have.    Newer vehicles have more technological advancements, but do you really need them?  Bikes are a little different in that some technology advancements make a real difference.  

For instance, my old road bike has friction shifting; indexed shifting is a real game changer and requires less of your energy since you aren't constantly trimming after each shift.  My touring bikes have indexed shifting (for the rear cogs, friction shifting for the chainwheel), and I'd never consider going back to friction shifting.    OTOH, I have no interest in electronic shifting.  It's fine, and eventually most bikes will be sold with it, but it adds some complexity & requires charging a battery and doesn't really make things easier for a touring cyclist.  I certainly wouldn't buy a new bike just to have electronic shifting.

Disc brakes are a whole different technology advancement.  They are so much better than the rim brakes I used for decades; there's really no comparison in my opinion.   You have to buy a new bike if you want to upgrade to disc brakes because the frame must be built for them and the fork must be stiffer.   I witnessed 2 cyclists get in trouble on rim brake bikes in the Appalachians while riding the Transam route - one wrecked and the other narrowly avoided death from a near-collision, both cases due to wet rim brakes.  Replacing an older bike with one that has disc brakes is a wise move that could potentially be life-saving.  

 Many technology "advancements" aren't as beneficial for cycle tourists as they are for racers. For instance, 12-speed cogsets are the rage for lightweight road bikes these days.  You can ride a 1x12 setup and eliminate the front derailleur and save some weight on the chainwheel.  But doing so requires a thinner chain and a greater amount of "cross-chaining" at the extreme gears, both of which will cause the chain to need replacement sooner.  This may be fine for racers and other skinny lightweight folks, but I wouldn't want to go cross-country on a fully loaded bike using a 1x12 setup.  I'm pretty happy with my 2x10 compact double setup for touring, thank you.   

I like having a dynohub for having lights on 24 - 7 on tour.  Of course, that means having a wheel built around the dynohub.  You don't have to get a new bike, just a new wheel, if you want that technology - but it could be a significant issue in the decision process if you are leaning towards a new bike anyway. 

Frame weight is a factor in the decision process.  Carbon fiber is now a serious option for a touring bike.  I'm a "steel is real" guy and am not interested in spending thousands of dollars to save a couple of pounds, but 2 - 3 pounds is a significant weight saving for some folks.  Buying a lighter-weight frame could be one reason that justifies a new bike for many folks.  

"Doc," my brother-in-law and riding partner on last year's Northern Tier tour, is very much the opposite of me in terms of technology - he buys every new gimmick available as soon as possible.  So he rode a carbon fiber touring bike with 1x12 electronic shifting and a tubeless tire setup for the 4,300 mile trek.  He also had frame bags (a "bike-packing" setup) as well as panniers, cause frame bags are sort-of a new gimmick - I say "sort-of" cause we had frame bags in the 1970's.   He didn't have a handlebar bag cause he had carbon fiber handlebars and - you know.  He made it just fine using that setup, and had no flat tires either.  I made it just fine using a more traditional setup, and also had no flat tires.   So there you go - both new and more traditional technology rode coast-to-coast with no real issues.  Each of us visited a bike shop once on a rest day for minor adjustment issues that we could have done ourselves.  

Your new-to-you bike looks good to me, but folks say that I have gaudy taste. If you buy a new bike, will you be getting new or advanced technology that makes a difference for your use?   Or, you know, if you want a different color bike...

The new orange bike has a lower bottom bracket than the other two bikes. Almost as low as on a diamond frame bike. Kind of like a Rans crank forward bike.

At the risk of boring the non recumbent riders here, I will offer that the orange bike has the biggest 'drop'. That is defined as the difference  between the seat height and the pedal height. More drop is desirable, as it should give the rider more pedal power. Example - if the seat height is 20" and the pedal height is 14", then the drop is 6". Those are imaginary numbers to use as an example.

I also have to remark about your 15 year old touring bike's maintenance. I know you carefully track and care for everything - personally! No bike shop for you.

It's an interesting note that you've worn out four rims from braking. I consider myself a cautious downhill rider, and I live in the mountains. I have yet to replace a rim, and I do use rim brakes.