Broken teeth on rear cogs?

[MrMonster]

Not sure if this is the appropriate forum, apologies if i'm wrong but it seemed more like maintainence and I thought I would seek advice.

I was mountain biking through a local woodland a few weeks back when I went over a pile of leaves and a damn long metal wire wrapped around my rear derailleur and frame etc and when I managed to bend it all and get it off I noticed it had taken out half the teeth on my 7th gear.. Was just wondering how much I am expecting to pay to get this fixed? Is it worth it or can I just go around missing out that gear?

Thanks for your advice.

 

[Steve Austin]

You'll need to replace the cassette, if you have lost teeth.

As for cost. it depends on what level of kit you want to buy and if you can fit it yourself, and have the tools to do so.

 

[MrMonster]

Oh that doesn't sound as small as I thought it would be :s
Is it worth doing so? I very rarely use that gear anyway, generally 1-12 when mountain biking so it's not absolutely necessary, unless it affects anything else?

 

[Dan B]

It could potentially be very uncomfortable if you forget the teeth are missing and shift into that gear, as the chain may slip and you could potentially end up sitting down hard on the top tube.

Other than that, I don't think it would have any kind of knock-on effect on the rest of the ring. But: new cassette £20-40; continued reproductive health: priceless

 

[MrMonster]

I have had that happen a few times, especially when I start riding from standstill it sometimes drops when not greased enough and I end up, as you said legs either side of the bar. Doesn't happen very often though. Are they quite simple to fit on your own? I am considering going and purchasing one because the price isn't too offputting.

 

[Dan B]

If you have the correct removal tool (about a fiver?) it's a fairly simple job.

 

[MrMonster]

What is that tool? My dad has quite a bit of knowledge on bikes and may know himself, just haven't got round to asking him so it may be possible if he has the tool you are talking about. Ty btw.

 

[ASC1951]

What is that tool?

Probably this, given that nearly all MTB drive trains are Shimano http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=10183
You might also need a chain whip, although you can get away with a piece of old chain and some molegrips.

It's physically straightforward to change a single cog on a cassette, Danny, but difficult and expensive to get the cogs separately. If you end up getting a new cassette this time, it might be worth keeping the old one for spares because by the sound of it all the cogs are unworn apart from the one you have just broken. (Don't mix new and well worn cogs, though - it's a sure way to bark your right shin on the chainwheel!)

Ty btw.

Steady on, lad. Most of us on here are many years too old for txt spk.

 

[MrMonster]

Thanks ASC! It is a Shimano Tourney set on the back, that's as much as I know!
I'll have a look at the link and give my Dad a call and see if he knows how to replace them, if not will Halfords do it? Not sure if I can do it first time round. I probably would keep it as spares, other than the 7th gear, the 6 gear has one missing tooth but that's never been a problem for me at all.

Apologies! Read through it and added it before I sent, next time I won't be so lazy and say the real thing

 

[02GF74]

yeah, it is a real pain that you cannot buy the sprockets separately or probably be able to take the cassette apart.

Generally, when commuting,m you do the same journey over and over and will tend to use a very limited number of sprockets that get all the wear. when you replace the chain, it is those most commonly use sprockets that may have the chain jumping - it would be nice to be able to replace them too.


but ofcourse that would loose the manufacturers money.

 

[ASC1951]

I'll have a look at the link and give my Dad a call and see if he knows how to replace them, if not will Halfords do it?

I'm not as rabidly anti-Halfords as many on here (after all, they stay in business because they provide a lot of people with reasonable goods at a reasonable price) but on principle I would try my LBS first for repairs and servicing. After all, if you are going to take up cycling, you will need to build up a relationship with a proper shop.

Not sure if I can do it first time round.

It's not as difficult as many bike jobs: a new cassette is just a swap job, with no fiddly adjustments. I would get a cassette tool from your LBS and give it a go. Here is how you do it. http://www.parktool.com/repair/readhowto.asp?id=48

A lot of us swear by the late great Sheldon Brown. A wonderful man and a wonderful site. Here is his article http://sheldonbrown.com/k7.html#remove although the whole site is worth a good browse.

If you get stuck you can always ask on here. A friendly lot, provided you avoid the P & L section.

 

[ColinJ]

Just one thought (apologies if teeth definitely have broken off) - are you sure that you aren't mistaking the deliberate cut-outs that some teeth have, for broken teeth?

Some teeth are specially shaped to facilitate shifting between gears. The first time I looked at such a cassette, I thought I'd broken teeth off it.

 

[02GF74]

^^^ good point.

when I was trining for time trial I once managed to shear of some teeth of a cassette.

those were the days, thighs the size of bolivia........

 

[MrMonster]

Thank you ASC, i'll look at that and attempt it myself. If worst goes to worse, i'll just pay someone to do it.
Also, what is LBS? The only bike place I know of around here is Halfords, which is why I mentioned them, and EvansCycles online of course.

Colin + 02GF, i'm sure they are broken, I have torn almost 3/4 of the teeth on that cog off and whenever I put it into that gear it just slips and I end up with legs either side of the top bar.. So it's definitely broken! Thanks for the input though

 

[JohnW]

LBS is Local Bike Shop.