masopa

Hi guys - complete newbie here and I can't find my answer on the search so obviously nobody has been quite as newbie as me before!

I have a really daft question. I'm about as inexpert as anyone can be on bikes so please bear with me. I bought a cr@ppy cheap "bike in a box" for my wife (I tried to dissuade her, but you know...)

It came mostly assembled, just had to fix the seat, handlebars, front wheel and pedals. Simple and took next to no time. If I knew what I was doing I might have been more adventurous and made sure the already assembled parts were greased etc. but as I said, I'm a novice who knows my limits.

Now, the weird thing is that when you turn the pedals with the bike upside down, as long as you don't turn them too quickly / aggressively, they spin the rear wheel. But, if you apply too much angular acceleration (or whatever it's called) or try it with the bike the right way up, the pedals turn but the chainring (or whatever it's called - the front gears) don't turn. As I hand-crank the pedals I can feel it rumbling slightly, as if it's trying to catch slightly on something but failing...

It's dark outside now so not sure how good the pictures might be but I'll try to take a couple in a tick to show what type of (cr@ppy) bike it is...

Any ideas whether I just need to tighten something up or will I need a new cassette-type-thing? TIA!

masopa

Right, attached is the best picture I can take. The pedals are not connected to the chainring in any way - they appear to be independently linked (in some way but clearly not the right way) to the spindle. There isn't a "spider" or anything connecting the cranks directly to the front gearset - the plastic thing which looks a bit like one is just a cover for some allen bolts...

z415

OK, well I see one thing wrong. That clear plastic thing has a gap in it. That should not be visible, but hidden under the arm of the crank. That gap is supposed to be cut out for the crank arm.

Was the crank attached to the bike in the bike of did you do that?

Preliminarily, it sounds like it may be that the bb spindle/crank interface have not been tightened. Does that whole assembly you pictured wiggle laterally?

bleukahuna

Is this by any chance a self shifting system?

z415

^ Yea, giving us the whole bike would be helpful. More info never hurts.

operator

Time to get a real bike shop to assemble that properly for you. You are in way over your head

urban_assault

Looks kind of like a LandRider crank.

I'm not trolling, but are you turning the crank in the right direction?

https://landriderbikes.com/bike_assembly.html

masopa

Thanks for the advice, guys. Yes, I was turning the cranks the right way (always worth asking though!)

Based on your recommendations I took the bike back to the shop (it wasn't a bike shop, more a general store). They refunded the purchase price in full and we then wandered along to our nearby bike shop and bought something a bit more reliable which they're currently building for us.

Thanks again!

jccaclimber

Why can't every thread take this path?
1)OP buys poorly made bike at box store, admits faults, attempts to describe problem, and provides a picture.
2)Members chime in on a solution, without too much sarcasm.
3)OP Not only returns the box store bike, but also goes to a shop, and thanks everyone.

OP-parktool.com and sheldonbrown.com are also great places to learn to fix this stuff on your own should you ever want to. If not, I'm certainly not going to try to dissuade you from supporting the LBS.

masopa

Thanks for those links. I'd already taken a look at SB before posting here but, to be honest, it was a bit over my head. I think once we're using our bikes a bit more and get comfortable doing the regular stuff (repairing punctures etc.) then I'll gradually progress to try to do more things. Modern bikes seem a fair bit more complex than the old fixed-gear things I mucked around on as a kid years ago so I'll take it slowly and hopefully not destroy too much kit in the process!

Cheers again...