Chain drop

Hruška

Warming-Up
Sep 13, 2010
4
0
0
Tokyo
#1
Mechanic meisters.....

I had a new group installed and rode for months with no problems. Now on a couple rides recently (but not consistently) my chain is dropping on the shift from big to small chainring.

I have taken a look at the biggest cog on the cassette / small chainring setting and the chain is very close to the inside of the front derailleur. IE this looks ok, at least to my untrained eye, and I don't think is the cause of the problem (plus I can put the back wheel on a stand and shift a hundred times from big to small with no drop).

The drops have happened I think with the chain on the 3rd or 4th biggest cog on the cassette, so I don't think the angle of the chain is a cause either. btw, I'm running Campy 11 with 34/50 crank and 11-25 cassette.

I'm an awful mechanic when it comes to fine-tuning like this, plus i just moved and only have basic tools. If I can find a K-Edge Chain Catcher around town I'll get one....but even though I get piece of mind this will still not solve the problem.

Any ideas? I've thought somehow maybe pedal torque or cable tension - the drops seem to happen when I've started a climb in the big ring and shift down to continue. But it's not like this is any new behavior, so why now?

Grateful for any thoughts, thanks...
Mark
 

andywood

Maximum Pace
Apr 8, 2008
1,753
1,393
133
Niigata
#2
I too drop the chain sometimes. I usually find it happens in races as a climb picks up and I shift up at the back to get ready to shift dow at the front. It's a quick action and I probably end up doing both simultaneously which leads to the chain dropping.

I find the chain is more likely to drop when the drop between the two rings is bigger (ie. when using a 50/34 or 53/38 as opposed to a more traditional 53/39).

Don't know what the "K-edge" retail at but you can get a simple plastic "chain guard" which you clamp to the downtube and costs just a couple of hundred yen. An essential bit of kit if you ask me.

Andy

www.jyonnobitime.com/time
 

Ludwig

Speeding Up
Oct 9, 2008
871
0
36
Setagaya-ku, Tokyo
#3
Same experience here - it happens sometimes when shifting simultaneously on both front and rear, in the same direction. I always manage to get the chain back up right away. The trick is to immediately shift back into the outer ring and pedal gently, while continuing to ride. Then quickly back to the small ring, which one usually needs right away, as this usually happens at the start of a climb.

It's slightly annoying when it happens, but really only slightly.
 
May 22, 2007
3,630
1,469
143
Kawasaki
halffastcycling.com
#4
My experience is a little different - slight threadjack

Three times recently my chain has dropped over the largest (28) cog on my cassette, into the space between the cassette and the spokes. Total jam and I can't go forward or back.

This happens when I quickly shift up several steps under load, e.g., realising too late that the bridge ramp I'm tackling is steeper than I thought. Under these circumstances the problem is reproducible.

I then have to get off and unwind the chain by hand. I'm getting better at it, but it's still a real nuisance.

This is my new 2011 Shimano 105 groupset; compact crank and 11-28 cassette. The limiter screws and cable tensions all seem set up correctly. Wondering whether it's just a chain tension thing that can't be helped.

Any similar experiences or suggestions?

--HF Mike--
 

Ludwig

Speeding Up
Oct 9, 2008
871
0
36
Setagaya-ku, Tokyo
#5
Indeed, chain drop on the rear cassette is a big problem! In fact, it is easy to destroy rear dérailleur and possibly some spokes this way.

I have had this happen to me only once, very recently on my bike with the old 105 group set. Fortunately, I was not applying any force to the pedals and so did not destroy anything. I have since adjusted the dérailleur settings slightly and hope it won't happen again.

I would try the same if I were you - chances are that a small adjustment may prevent this from happening again.
 

andywood

Maximum Pace
Apr 8, 2008
1,753
1,393
133
Niigata
#6
Mike, if the chain drops between the cassette and the spokes, I would think it is the limiter screws that need adjusting. Does your chain rub against the spokes when in the biggest cog at the back? That's a sure sign that you need to adjust the screws.

Personally I never do much fiddling with the derraileurs myself as I tend to just make it worse. A few minutes on a stand in a bike shop is all it should take.

Andy

www.jyonnobitime.com/time
 

Hruška

Warming-Up
Sep 13, 2010
4
0
0
Tokyo
#7
Guys, thanks for the continuing thoughts.

And Andy, I totally agree about fiddling and making the problem worse!....so, when you need a few minutes on the stand at a bike shop, where do you go? I'm looking for a shop for the harder repairs, etc - some old posts here but wondering about lately. I've heard mixed reviews....

Thanks again,
Mark
 

DanBell

Speeding Up
Apr 26, 2010
212
2
38
Kawasaki
#8
I've had very good experiences at Nalsima, although they get really busy and can't always do stuff on the day, and Nicole (just tonight in fact). I went to Nicole specifically because I thought they would be less busy than Nalsima on a Friday night.
 
May 22, 2007
3,630
1,469
143
Kawasaki
halffastcycling.com
#9
Mike [...] Does your chain rub against the spokes when in the biggest cog at the back?
It doesn't; everything looks to be in line. I'll have a fiddle with it tomorrow morning on the big repair stand.

I'm not scared of those screws. Although I can never work out just by looking what screw is supposed to have what effect, I reckon if I turn something half a turn in one direction and it doesn't improve the situation I can put it back where it was and I should be no worse off.

Famous last words!?

--HF Mike--
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#10
Guys - one thing to check always is the parallellness of the rear Derailer. Park has a nice tool for this - but essentially if the rear hanger does not provide a parallel positioning for your derailer then you'll have nothing but hassles trying to get a perfect shift. It wont matter the end stops at all - and in fact , you will probably end up over stopping your derailer which will get your shifts but highly increase the chance of chain throws.
 

Ludwig

Speeding Up
Oct 9, 2008
871
0
36
Setagaya-ku, Tokyo
#11
Guys - one thing to check always is the parallellness of the rear Derailer. Park has a nice tool for this - but essentially if the rear hanger does not provide a parallel positioning for your derailer then you'll have nothing but hassles trying to get a perfect shift. It wont matter the end stops at all - and in fact , you will probably end up over stopping your derailer which will get your shifts but highly increase the chance of chain throws.
I agree. If the derailleur is perfectly positioned, it is quite hard not to get the adjustments right. There are only three "variables", and two of them are really easy to get right as they just determine how far the derailleur can move up or down. So effectively, there is only one variable left to get right, and with a bit of trial, that should always be possible. Things get frustrating when the derailleur is not perfectly aligned, and then one needs a special tool (like the above, but there are other manufacturers too) to get this right.
 
May 22, 2007
3,630
1,469
143
Kawasaki
halffastcycling.com
#12
Wise words about derailler hanger alignment. I carry a spare hanger on my carbon bike now, after twice having to take the bus/train home after a minor spill.

I had a good cleaning session today and I think my problem might have been a lack of lubrication in the derailler mech leading to a delay in it picking up the chain tension. Or something like that; I could be bluffing. Anyway it's been thoroughly greased now. New saddle too. Now all I need is nice weather!

--HF Mike--