MeagreAger

The bike I am currently riding is an Ironman David Scott Centurion from the 80s. I purchased it 2 years ago off Craiglist for $275 and have ridden it regularly since then. Recently I've begun training with a cyclist who competes at a national level. I rely upon him to tailor our workouts as we do a variety of intervals that all depend upon reaching a certain wattage which he monitors through a computer mounted to his stem, connected to a power meter. The information he obtains through this setup seems invaluable to developing and maintaining a training program. However, it's also expensive, as is a proper road-bike. I don't compete in races, but am tempted to do so, which may require a bike other than a centurion. My questions are, if given a fair deal, what should one at minimum expect to pay for a road bike that would both last and be able to compete, though I imagine at a disadvantage to more expensive models, in Criterium? The main issue I experience with the Centurion is the downtube shifting, though perhaps I should consider its weight too. If I were to stick with the centurion out of interest in training for the sake of fitness than racing, are there cheaper-end models, or simply ones used, of power meters and computers that I could purchase that are deemed reliable by the community that uses them?

Carbonfiberboy 

Oh my yes, you'd notice quite a difference with some modern equipment. I'd say - don't buy a new bike, buy a used carbon bike, old enough that it's for sale because the owner upgraded. 10-speed is probably the sweet spot. Buy a rear wheel with a wireless hub power meter on ebay if the bike doesn't already have one. Hub meters are for sale because so many people are going with crank and pedal PMs. For a head unit, get a Garmin 800 or 820, ebay again. I have 2 Garmin Edge devices I bought on ebay years ago, never a problem with them. You'll also need to upload your data to somewhere I use TrainingPeaks, premium subscription.

The tricky thing with buying a used bike is fit. You can use a bike fit calculator to get suitable frame dimensions and then refer to manufacturer's charts of their bike dimensions to see if a bike will work for you or not. You should be able to narrow the sizing thing down fairly quickly by researching a few candidate bikes. I'd want to have any used bike I was buying sight unseen inspected by the seller's bike shop.

rubiksoval

If you're good enough, the bike isn't going to significantly hold you back. After all, people that start racing way below their talent levels typically take off and win solo, so...

DT shifters can be a hindrance in a group, though, especially in crits in which you're oftentimes shifting right before and after a corner and you can't really take your hands off the bars until you've straightened out, so you may not be in your optimal gear (after a few laps, though, you could pretty easily figure out the right gear and just make sure you're in it before a turn... like everything, people had lots of success using it in the past, so...)

I'd buy used for everything. I've bought a used Ultegra equipped bike for $750 and a used powertap for 300 (back when they came on to the market...like 2005). It might be a bit tougher to find an Ultegra bike for $750, but three years ago I bought a Sram Rival bike for $1000 with a Zipp front wheel which I sold for $400, so the bike was essentially $600. 105 equipped bikes should be able to be found under $1000. And powertap wheel sets can still be found for $250-400 pretty easily (if you go that route, only get the G3 version, though, not the SLs). Quarq powermeters can also generally be found in the $400-600 dollar range, but you need to be familiar with bottom bracket compatibility as it's very different on every single bike (seemingly).

But this is searching through and buying through facebook groups and ebay, so you'd likely have to have it shipped and wouldn't be able to see it beforehand. Could be an issue if you're not very familiar with stuff. Maybe have your friend take a look?

Anyway, I'd say at a minimum for bike racing on something that will last you more than a year: $800 for a bike (Shimano 105 would be the lowest group I look at personally for durabillity reasons), $300 for a powermeter, $200-300 for the bike computer to read the powermeter, $200 for clipless pedals and shoes if you don't have those. $30-40 for water bottles and cages. $50 for a pump/tube/bag/tool. Another $100 for a good pair of tires and tubes on sale when you're ready to start maximizing speed, $50-100 for summer clothing, probably double that for winter if it gets cold.

Bike racing is expensive, too. $100 or whatever it is these days for a license, plus anywhere from $25-50 for each entry fee (which is crazy steep if you're doing a 20 minute Cat 5 race multiple times each month).

adamrice 

• Power meters are expensive, and there's not much getting around it. You can buy a single-sided crank-based power meter for about $300 over the price of a plain crankset. There are also pedal-based and hub-based power meters, but there are more options for crank-based ones. It would be kind of weird to put a power meter on a vintage Ironman, but there's no technical reason you couldn't.
• With bikes as with so many things, spending more money results in diminishing returns after a certain point, but with bikes, that point is pretty high—I'd say it is in the $1500-2000 range (if buying new). I agree that a "105-grade" bike is a good baseline to aim for. FWIW, upgrading an old bike could turn out to be more expensive than just buying something new/newer.
• In general, new-ish used bikes can be a great deal, and there are also vendors on eBay who specialize in selling NOS bikes at significant markdowns. Although with the current bike boom, finding anything is going to be harder.
• Power meters are training tools. There's a whole conceptual framework around training to power, and you'll need to invest some time and mental energy in studying up on this in order to benefit from having a power meter.

treebound 

For me personally, I'd first look at pedal based power meters since they are easy to swap between bikes.

Then work with the meter and the person you are training with and learn how to utilize the data.

With so many races being cancelled or altered due to this pandemic stuff, I would just start watching your local used market and get a feel for what bikes sell for while you sort out your needs.

Just my opinion, do what works for you.

BritishV8

+1, and for training a Favero Assioma power meter will work great with a smartphone, thus saving or delaying the expense of a separate bike computer.