Giant bike cranks after 20 deg rotation

[daniil]

i just purchased new Giant cypress. there is strange knock when i ride with pedals in horizontal position and starting to rotate the pedals trying to accelerate. i have to rotate up to 25 degrees before it starts to crank. in this moment it make metallic knock. i do not think it is normal. even my old cheap bike did not do so...

does anybody know what's wrong with the bike? How to fix it?

i would very appreciate your help. thanks

[AndrewB]

Congrats on your purchase. It's too bad the bike isn't working perfectly out of the shop. I'm assuming you did buy it at a local bike store?

You'll probably have to take it back to them or to another store to get the crank repaired. It's fixable, but you'll need some tools to do the work. Chances are they didn't assemble it correctly or used an incorrect part that doesn't fit your bike.

Report back.

[JohnV]

You should be able to take it to any Giant dealer and they will fix it for you as the bike, being new, is still under warranty. I don't know your location, but here in Tampa, there are several Giant dealers and any of them will work on warranty work.

BTW, one of my two bikes is a Cypress and I love it. Unless I am training for a long distance ride, I ride the Cypress more than my Defy because it is a heavier bike and I get a better cardio workout from it. I bought it last July and have almost 3,000 miles on it. The Defy was purchased in October and between the two, I have over 4,000 miles on them.

[daniil]

Thanks for reply.
i went to Intersport, where i bought the bike, but the technician thinks it is normal.
i suspect loose chain or lack of lubrication somewhere. but where?

[cyclerUK]

(05-21-2011, 09:06 AM)daniil Wrote:  Thanks for reply.
i went to Intersport, where i bought the bike, but the technician thinks it is normal.
i suspect loose chain or lack of lubrication somewhere. but where?

Technician "thinks" it's normal.
There is no thinking - it either is or it isn't?
There should be no "knock" on a new bike.
If unsure then take it to another bike shop for another opinion, or ask an experienced cyclist friend for theirs.

[JohnV]

CyberUK is 100% correct. There should be no knocking, grinding or clicking noise on a new bike. However, reading your post again, I'm curious to know if this happens when you start pedaling after coasting and what gear this happens in? I'm just wondering if you are in between gears on left grip shifter when this happens?

[daniil]

Yes. after coasting, when i want to accelerate, the pedals move freely for 15-20 deg. without any resistance before engaging in cranking. The mechanism meets some kind of obstruction with a sharp metal knock and starts cranking. It happens in all gears.

[JohnV]

Strange! I would take it to a different bike shop and see if they can isolate the problem. If it's not a Giant dealer, at least you know what you can tell the mechanic where you bought the bike. That is definitely a warranty issue.

[AndrewB]

I concur with JohnV - try another LBS.

Story: I took my almost new bike to a LBS to get a routine service - tighten the cables, adjust brakes, lube and check. What I didn't realize is that they stripped the cable bolt on the front derailleur until months later. They put a little piece of wire in there such that the screw would hold. After backing it out, finding the wire, the screwed up threads on the bolt and the derailleur, I realized I was in a hole. Grrr. They should have at least told me and offered me a deal.

Learning from story #1: inspect all LBS work, ask questions

Learning from story #2: use bicycletutor videos and do more of my own maintenance

[daniil]

Returning to my original issue, I would expect that play in the pedals would be 360
degrees divided by number of teeth. It should be few degrees. So, why the
Shimano on Giant bike has 20 degrees free rotation whithout cranking???
The knock is annoying...
Is there good mechanic on line?

[Painkiller]

try out another wheel from a buddie see how it acts. tell your shop to humor you for moment have them do it. If it does work right thats your problem, then tell your shop to fix that wheel and make it slip so they do not sell some else a wheel that does not slip.

[cyclerUK]

Which "teeth" do you you mean?
By "knock" do you mean the clicking of the freehub in the rear wheel?

According to Giants website specification the hubs are not Shimano. (Joytech).
http://www.giant-bicycles.com/en-gb/bikes/model/cypress/7854/45482/

If you are are talking about the take up of the freehub ratchet then if you turn the cranks backwards you will hear the clicking of the ratchet. This will give you an idea of the angle the cranks have to turn before the ratchet bites.
Some freehubs are noisy and others virtually silent.
The freehub on my Mavic wheel is very noisy compared with my Shimano,s.
So it may be down to the design of the hub.

If your problem is different to the above then we would need a better explanation.

[daniil]

Which "teeth" do you you mean?
By "knock" do you mean the clicking of the freehub in the rear wheel?

///Yes.

If you are are talking about the take up of the freehub ratchet then if you turn the cranks backwards you will hear the clicking of the ratchet. This will give you an idea of the angle the cranks have to turn before the ratchet bites.

///I did it. If I turn the pedal backwards and forward again, it cracks in a couple of degrees....that is what suppose to be!
So, why in free run (coasting), when I'm trying to accelerate, I have to turn almost 20 degrees???

Some freehubs are noisy and others virtually silent.
The freehub on my Mavic wheel is very noisy compared with my Shimanos.
So it may be down to the design of the hub.

If your problem is different to the above then we would need a better explanation.

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I THINK WE VERY CLOSE TO RESOLUTION!!![/b]

[cyclerUK]

When you are free-wheeling, have a glance down at the top run of the chain and see if it's drooping in the middle.
If this is so then the chain slack has to be taken up before drive will kick in.