Bicycle Mechanics - (Video) What happened to my cassette ? (Loose cogs)

The smallest cog says 'lock' on it, so I believe I have a cassette.
During my last ride, I heard strange noises from the cassette.
On certain gears, the cogs have no traction on the hub and me pedaling does not advance the bike.

Please view the video below.

https://vimeo.com/52736184

Do I need to tighten something that I can see in this image?
http://i.imgur.com/TWOH7.jpg

Only counting 6 cogs there, all cassettes (except some really old Suntour 6 speed) are 7 speed or more now.

Also, there is a big gap (which indicates that this is a cassette, not freewheel) between what looks to be the lock ring, and the first cog, this suggests that a cog (smallest) is missing, and / or a spacer at the rear may be missing as well.

Only counting 6 cogs there, all cassettes (except some really old Suntour 6 speed) are 7 speed or more now.

Also, there is a big gap (which indicates that this is a cassette, not freewheel) between what looks to be the lock ring, and the first cog, this suggests that a cog (smallest) is missing, and / or a spacer at the rear may be missing as well.
I did hear two things fall to the ground but there were cars behind and I did not want to cause traffic jam. I will look for these tomorrow in the road.

It's time for a new freewheel.

I'll tell you why I'm pretty sure it's a freewheel. It looks to be a GMC Denali road bike, which has 21 speed gripshifters. Also, as far as I know, no bolt-on cassette wheels are on the market.

It's time for a new freewheel.

I'll tell you why I'm pretty sure it's a freewheel. It looks to be a GMC Denali road bike, which has 21 speed gripshifters. Also, as far as I know, no bolt-on cassette wheels are on the market.
Yes it is the GMC Denali.
Do I have flexibility for replacing it?
I would be happy if I could actually have a larger biggest gear for downhill.
The 'specification' that came with the bike say the bike works with a different tooth combination where the largest cog's number is 34T instead of 28T.

For tools will I need more than "chain whip" and "lockring spanner"?

Yes it is the GMC Denali.
Do I have flexibility for replacing it?
I would be happy if I could actually have a larger biggest gear for downhill.
The 'specification' that came with the bike say the bike works with a different tooth combination where the largest cog's number is 34T instead of 28T.

For tools will I need more than "chain whip" and "lockring spanner"?
You can put any 7 speed freewheel you like on it, except one of those megarange gear freewheels. For tools, you'll have to figure out what kind of freewheel that has, and then buy the corresponding tool. Or just go to your LBS and pay them the $5 or $10 it takes for them to remove it.

Is there anything wrong with this freewheel? (http://www.amazon.com/Sunrace-7-Speed-Freewheel-14-34-Silver/dp/B002I7IC26/ref=sr_1_17?ie=UTF8&qid=1351971208&sr=8-17&keywords=7+speed+freewheel)
It says megadrive. Is that different from megarange?

Same thing, different brand. Why would you need lower gears to go downhill?

Same thing, different brand. Why would you need lower gears to go downhill?
I want a larger biggest gear. Would this correspond to larger number in the 14-34? My original is 14-28.

Yes, the freewheel has come apart, probably some pressed on ring on the back broke. The deal with the larger bigger gear is it's different than the front. A big chainring in front is the high gear, but its the small cog in back that is the high gear. So if you wanted a high gear to pedal down hill would want a smaller cog on your freewheel. Unfortunately to find a freewheel with a 13t or 12t cog would probably cost half what you paid for the bike.

If you want a higher gear then get a freewheel with a 13, I can't remember if a 12 is available, a 14-34 will get you a lower bottom end not a higher gear.

Unfortunately to find a freewheel with a 13t or 12t cog would probably cost half what you paid for the bike.

Maybe if he got the Denali used. 13-28 HG37 are typically around $20 tops. 13-25 Sunrace for $16

Maybe if he got the Denali used. 13-28 HG37 are typically around $20 tops. 13-25 Sunrace for $16Unfortunately the 13t freewheels you mention are 7 speed. The current 6 speeds only seem to come in 14T.

Unfortunately the 13t freewheels you mention are 7 speed. The current 6 speeds only seem to come in 14T.
It's a 21 speed bike, meaning that the OP lost a 7th cog on the freewheel.

Only counting 6 cogs there, all cassettes (except some really old Suntour 6 speed) are 7 speed or more now.

Also, there is a big gap (which indicates that this is a cassette, not freewheel) between what looks to be the lock ring, and the first cog, this suggests that a cog (smallest) is missing, and / or a spacer at the rear may be missing as well.

I would like to see a pic of the wheel off the bike butI really think tht is a 7spd cassette. The smallest cog is not screwed on and there appears to be lockring of sometype. I think if this was a freewheel and the last cog (that screws on) was broken causing everything to be loose, the cogs would be hitting the frame too.

I suspect a cog broke off and not a spacer.

http://sheldonbrown.com/free-k7.html


I believe the older shimano Uniglide cassettes were also 6spd.

Yeah, Denalis come with 7-speed, but typically freewheel on the blue ones, dunno about the yellow ones.

One of the cogs likely cracked in half and fell off.

I was going with the six cogs in the photo and the OP's statement
The smallest cog says 'lock' on itWhich would seem to indicate that all the cogs were there; at least the smallest cog anyway. I am also assuming the freewheel looks something like this Sunlite; it uses a cassette like carrier with the smaller cogs and a lock ring at the end. But I have not seen any 6 speed Denalis so I will defer to 7 speeds.

.282047

I want a larger biggest gear. Would this correspond to larger number in the 14-34? My original is 14-28.

For a bigger gear, you need either a bigger chainring, or a smaller cog in the rear, as it's a ratio. A 13-28 freewheel should do the job. :thumb: