Aaron wrote an excellent article about selling bikes online, but when it comes to purchasing a bike, the rules can be completely different for potential buyers. This article focuses on purchasing bikes from other individual sellers, not a new bike from an online retailer.

Choose your Used Marketplace Wisely

eBay is undoubtedly the most popular online market for new and used bikes and parts, but it has limitations. First, you cannot physically inspect or demo the bike. Look for auctions that allow free returns, and preferably free shipping. It is a very good idea to purchase from sellers with a lot of positive feedback (>100), and preferably ones that deal with a lot of bike parts.

Ebay can be a great place to get a good deal, but you have to be judicious about what you buy.

Craigslist is the most popular local marketplace, but there are a few other ones out there that are usually specific to cities or certain areas. This venue allows you to get your hands on the goods physically, but also takes more time because you have to meet sellers, instead of simply and quickly placing bids online. Safety is also a concern, as is the time and gas you might spend meeting someone. With Craigslist, the early bird often gets the worm–it is not uncommon for good deals to vanish within hours if other potential buyers are willing to drop everything and meet the seller as soon as the ad is posted.

There are also local swaps or meets, such as Veloswap, where hundreds or thousands of buyers and sellers can meet for commerce.

Ask Specific Questions

Bike owners who take care of their rides can usually tell you every detail about the bike they are selling, without hesitation. Those who have neglected their bike, or may be selling a stolen/damaged bike, may give you subtle hints in the way they answer (or cannot answer) specific questions about the bike. Expect clear answers with questions such as:

When and where did you purchase it?
How much did you pay for it?
Why are you selling it?
Has it been raced? Has it ever been crashed?
When were the fork and shock last serviced? Brakes bled? Stans refreshed? Brake pads replaced?
Inspect brake pads carefully. These are pretty close to needing to be replaced, which should prompt you to ask about when the brakes were bled, and how old the rotors are

Don’t be afraid to ask anything and everything. After all, this is your opportunity to find out if you want to hand over your hard-earned cash to buy the bike, and discover if anything seems amiss. If it does, walk away.

Inspect the Bike Carefully

No matter how clean and shiny a bike looks, it could potentially have structural damage or defects that the seller is concealing that could have catastrophic consequences. Manufacturer warranties rarely transfer to second owners, so typically the warranty voids as soon as you walk away with the bike. Buying a bike from a friend, or patronizing a bike shop that allows second owners to take advantage of warranty claims with original receipts, is one way to minimize potential financial loss if the frame craps out on you. So, if possible, get receipts, and get proof of regular maintenance. Take a very close look at the bike, taking note of the following:

Are the welds intact, and do you see any fracture lines around them? Specifically, look around the headtube and bottom bracket for cracks. Chainstays are also prone to crack, so look at them carefully for lines or damage.
Are there unusual areas of discoloration in the pain? Was touch up paint used?
Is there any flex in the rear triangle when you rock the rear wheel back and forth?
Do you see an dents, cracks, major dings, or signs of crashes?
If there is a carbon handlebar or seatpost, are they over-torqued? (It’s a good idea to bring a torque wrench and check the spec.)
Do the brakes feel solid? Do the pads need to be replaced?
How much life do the tires have left on them?
Pump up and down on the fork and shock. Any weird sounds? Oil leaking? Broken seals? Inspect the stanchions carefully for damage.
Inspect the chainring(s), cassette, and chain for significant wear. Bring a chain length tool if you have one.
Spin the cranks and see if the bottom bracket is smooth. Do the gears shift crisply? Are the cables old and worn?
Inspect the spokes and rims for damage. Are the hubs smooth, or do they grind?
If equipped with a dropper, inspect the function and look for wear. When was it last serviced?
Look for missing paint or dings in carbon like this. If you can push on it and it gives, it needs to be replaced. If you are unsure, have a bike shop inspect it

If possible, take the bike to a local bike shop (LBS) that you trust, to give it a thorough inspection. Some shops may charge a small fee, but if you are truly serious about buying that bike, the small investment up front will pay dividends down the road. Having it inspected is obviously far easier when buying from a Craigslister, but if you buy on eBay, look for items with a return period (generally 7-10 days) that will allow you to return the bike after inspecting it if something is wrong. It’s better to pay return shipping than be stuck with a dangerous junker.

Whether you buy a bike in person or win an Ebay bid, pull everything off that you can. This bike appeared to be in excellent shape, but when I pulled the seatpost out it was clear it needed to be replaced — Whether you buy a bike in person or win an eBay bid, pull everything off that you can. This bike appeared to be in excellent shape, but when I pulled the seatpost out it was clear it needed to be replaced.

Test Ride a Bike When Possible

I would strongly recommend not purchasing any bike, new or used, until you have ridden it. Just because you ride a size-medium Niner doesn’t mean that a size-medium Pivot will fit you. Know the correct size/model before shopping online, and don’t rely on posted geometry charts. Often you can do this at demo days that your LBS or a bike company may offer, or even pay to demo/rent a bike for a day or two. At the very least, get on it and take it for a 10-minute ride in the parking lot. This allows you to have some peace of mind about buying a bike online.

You'll know when a bike feels good to you. I demo'd this bike four different times before I made my final purchase decision because I could not decide between two models — You’ll know when a bike feels good to you. I demoed this bike four different times before I made my final purchase decision because I could not decide between two models.

If you are negotiating a sale via Craigslist or in person, however, insist on a proper test ride–even if you have to offer your current (crappy) bike to an untrusting seller so they can ride beside you. This will allow you to see the condition of the bike, ask informed questions about it, see if it fits and feels right, realize if any work needs to be done, ask about any defects or creaks you may encounter, and it will, of course give you some bargaining power should the advertised condition be over-represented.

Click here to read part 2!