Mother_of_birds

I just went and viewed a bike that the guy said he bought brand new and has only ridden 3 times (which I believe from the condition of the tyres), its a 2020 bike so obviously been sat for a while but other than the chain being a little rusted there was nothing else obvious to cause concern until I tested the gears. Its a 1x12 SRAM Eagle SX, and I didn't test ride just got the back end held up and as I was turning the pedals on the smaller cogs I noticed this kind of stick/jump/knock. The chain didn't jump to another cog or anything but there was definitely this feeling on the crank as I turned them and a sound that came with it. I couldn't work out exactly where it was coming from the the bloke kept trying to tell me it was the derailleur even though it was doing it when I was 'pedalling' not changing gears. I walked away for now as I'm not interested in fixing a huge problem, but if it's likely something simple like swapping the chain (which I would do anyway) then I'll go for it. If it sounds like something more complicated then I will let someone else deal with it. Anyone have any ideas? I realise its not much to go on and wish I'd taken a video now but maybe one of you has come across it before and know what I'm trying to describe!

shelbyfv

Since you were unable to identify the issue you are unlikely to be able to resolve it. Good call to pass on this one.

wheelreason

Could be a few different things, but chances are it's stiff links from sitting around.

Iride01 

Seldom used 4 year old bike doesn't make it perfect. They probably never took it back for the free inspection and adjustment the shop was going to do for it. So I'd recommend that be done if you or any other where to purchase it. Unless perhaps you are already well experienced with bike maintenance of the components on that bike.

But since you are asking here, you should take it to the shop. And you'll have to pay them. So find out what that costs and deduct that from the asking price before you get to haggling the price down further.

Just because it's only been used a few times, doesn't mean those components haven't been somewhat damaged. The owner might have no clue how to operate a bicycle and futched up something.

AxxisPowers

Sounds like you ran into a bit of a puzzle with that bike. It's definitely a good call to be cautious about any potential issues, especially with the gears. Without seeing it firsthand, it's a bit tricky to diagnose, but based on your description, it might be worth having a closer look at the chain and maybe even the cassette to see if there's any wear or damage causing that sensation. It's always better to address any concerns before they become bigger problems. Good luck with figuring it out!

MilhouseJ

I've experienced this exact thing as a seller. I met a guy to sell a bike, he test-rode it, told me he liked it and wanted to buy it. The next day, he starts asking me questions about how to shift it to different gears, as he'd only ever ridden SS bikes. The day after, he complained about the gears not shifting correctly. I told him I'd take a look and get it right without cost, he declined.
Fast-forward an unreasonable number of weeks, and he wants me to buy it back as a "good faith" gesture, because it just "didn't ride" and it's been broken since he picked it up. I told him that I would not buy it back. He insisted, and complained that he had to spend more money at a bike shop to get it fixed after he broke the chain. His claim was that I had put the chain on backwards (not a directional chain) and that the front derailleur wasn't installed correctly, with a small list of other problems. It ended with me telling him that he declined free repairs, and that I have no idea what he did in the interim time to mess up what I sold as a perfectly functional bike that I built for myself, only selling as I had found a better platform for the build I was intending. I also reminded him that he test rode it and didn't have an issue until we parted ways, I had no way of knowing that he didn't know how to shift through the gears.
In short, there's no way to know what people don't know and what damage their lack of knowledge has caused.

Mother_of_birds

I checked the chain and cassette. Cassette looked fine, no wear to the cogs and no rust that I could see. The chain though had started to rust and was stiff. Not completely rusted and not completely stiff but definitely needs replacing. That was my thought that it was caused from stiffness of the chain and it only was happening on smaller cogs because its a tighter arc for the stiffened links to get around.

I would say I can do the basics but definitely still an amateur at bike mechanics and not confident enough to diagnose the issue at least not while I was on the spot like that. The bloke is adamant on the price and to be fair I've checked sold prices for this bike and he's asking for like half. Then again of I know how expensive bike parts and repairs can be so I could end up spending the same amount trying to get that knock sorted plus the stress and hassle of doing so... OR could throw on a new chain, sorted and got myself an absolute bargain.

prj71

More than likely if it sat around for ~4 years it never got properly broke in and adjusted. What you describe is nothing serious at all.

If it's not a stiff chain as described above, then it's just a derailleur adjustment which is an easy fix (also cheap if you can't do it yourself). If it's not adjusted properly the chain will try to catch the next cog up or next cog down.

Iride01 

Slightly rusty chains will loosen up with use and lubrication. However they might wear out sooner. Replacing them is always a better solution if money is no issue requiring frugality.

When you compare prices of used bikes, take note of the components on the bike. That same model and year bike is very likely to have been offered with different components to let it be priced out at multiple price or tier levels. Even between my bike I bought in 2020 with Shimano's second best component group Ultegra Di2. It was still $8000 USD less than the top of the line bike in that model. Maybe more.

But if it's the bike you want, and fits you and is the color you like, then consider it. But do buy it with the expectation that it might cost you some big bucks to deal with unforeseen issues it may already have. Might see if the person will let you pay to have a bike shop inspect it before you lay out the full purchase. Then you'll only be out the cost of that inspection. Though you probably should ask at the bike shops to see if they are willing before you ask the seller.

Wileyrat

My first thought is a bit of derailleur cable stretch. That would definitely make it a bit wonky while you’re pedaling, and is incredibly easy to take care of. There’s a barrel adjuster at the shifter to take up cable slack.

PeteHski

This ^^

If you are confident about the seller’s claim of pretty much zero mileage, then it should be a very simple fix eg cable index barrel adjustment. New chain or something like a bent RD hanger at worst.

shelbyfv

FWIW, you can't evaluate cassette wear visually.

SoSmellyAir

No photos or video, so hard to tell 100% for sure, but it sounds like a new chain and RD adjustment thereafter would solve the problem and get you a bargain.

Camilo

My guess is that it's most likely the old, neglected chain and/or needing rear derailleur adjustment. Both are easy and cheap even if you have someone do it for you. However, it could be a damaged derailleur or a bad cassette, or needs new cabling, etc. etc.

The seller is dumb for not getting it in at least functioning condition before selling. But maybe they will find a buyer who can identify what's needed before buying and will make an offer accordingly

jaxgtr

If it has been sitting a while, as others have said, could be a few things, sticky chain, possible bent hanger on the derailleur. The SRAM stuff can be a little noisy when they are new, take a little bit of time to work them in, but sounds like it just needs to be adjusted and a new chain.

tomato coupe

If you deduct the price of a tuneup from the asking price, I'd say you've already started haggling ...

Reynolds 

Sometimes you can:

Mother_of_birds

Sounds like the general consensus is its likely to be chain/gear tuning which I can deal with. I'm about 99% sure I'm going to go for it. There is no more room for negotiation unfortunately since he's dropped the asking price by almost half already in order to get a quick sale so I doubt he'd be open to me getting it checked out prior to purchase as a few of you suggested. It does amaze me though when I see bikes up for sale and people can't be bothered to at least give it a clean and take decent pictures. I reckon if he had done then he would have sold for his original asking price no problem. I'm not looking for a bike to flip but it does give me a little peace of mind to know that I'm unlikely to loose money if it doesn't work out.

bboy314

Clean + decent pictures usually means higher asking price. When looking for a cheap used bike, expect at least some minor issues to sort out. This can be avoided by buying new.

bboy314

Clean + decent pictures usually means higher asking price. When looking for a cheap used bike, expect at least some minor issues to sort out. This can be avoided by buying new.

Also I highly recommend actually test riding the bike before buying.

VegasTriker

The SRAM Eagle SX is their entry level component. You might end up with a bike that gives you the same experience as this https://www.mtbr.com/threads/fed-up-...eagle.1144611/. Anyone who has ever worked in a bike shop can tell you that sometimes entry level components are just a PIA to deal with. If that doesn't convince you, read the first paragraph in the 5th response here https://www.******.com/r/mountainbik...gle/?rdt=44538 The good news is that you can use any SRAM Eagle RD in the series so an upgrade is possible but is it worth the trouble and cost?

alcjphil

One thing to keep In mind is that chordal action will make any setup run rougher the smaller the cog you are using. A stiff chain will make things worse. A bit of lube on the chain could make a big difference

wheelreason

"Oh dear God, I know I am not a good Catholic, and I haven't been to church in quite some time, but if you in your grace grant me the wish that just one customer comes in to the shop sometime in the near future, and utters these words, I promise to change my ways (right after the interaction of course)"...

MilhouseJ

"I bought something I don't know how to use, didn't ask questions at the time, wouldn't let the seller fix any issues I think I found, broke the thing, then paid more money to have it fixed. Why won't the seller just be reasonable and buy it back from me 7 weeks later??"

Mother_of_birds

For anyone who's interested, here's an update on the bike. I bought it. Cleaned it up, put on a new chain, tuned the gears, also had to replace the dropper cable because it was all kinked and not working properly, blead the brakes... and it's absolutely fine! No more clicking noise, everything works as it should!