How many links in your chain?

Lumen · 17-04-2010 08:03AM #1

I'm trying to fix my chain dropping issues. First step, get correct chain length.

I found this article from Park which has several equations (yay) for calculating correct chain length.

I created a spreadsheet of various gear combinations.

For my Scott Addict (405mm chainstays) the recommended number of links using the "rigorous equation" came out as anything from 45.3 (50-21) to 47.25 (53-27). << edit: no, it doesn't

I currently have 53 complete links in my chain, which would seem to be at least 5 links too many than the recommended 47-48 links for a 53-27. << edit: my assumptions were wrong

Anyone care to sanity check? (i.e. count the links on your own chain)

The chainstay length is a factor, so race bikes would be more useful.

I use 1.125 inches as the link size (1 1/8 inches), assume that is correct. << edit: no, it isn't!

Golfanatic · 17-04-2010 08:35AM

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

ive used one of these before and bike is perfect

lescol · 17-04-2010 08:39AM

WOW! That's some calculator, I was looking for the page being dated 1/4/10. When I last changed my chain on my Planet X I counted 53 links which agreed with this:- http://www.epicidiot.com/sports/chain_length_calculator.htm#results. Chainset is 52/39, cassette 12-25. Just ran to bike to double check...53 links

Lumen · 17-04-2010 08:47AM

Ah, OK. Dunno where I got the 1 1/8 inches per link from. Doh!

Lumen wrote: »

I use 1.125 inches as the link size (1 1/8 inches), assume that is correct.

Golfanatic · 17-04-2010 08:48AM

i reccomended that one over on another thread but now i prefer the other one

Lumen · 17-04-2010 08:50AM

Thanks, so my chain length is actually perfect already. Hmmm....

Lumen · 17-04-2010 09:24AM

OK, will look at front mech height and limits (angle is not adjustable as it's a braze on).

Maybe it's just poor shifting technique. The problem is that when I last dropped a chain I was so fried I can't remember whether it was dropped inside or outside, or how I was shifting at the time.

This makes me feel better....

lescol · 17-04-2010 09:42AM

I've only dropped the chain twice in nearly 2 years. On the W200 when I suddenly felt the need for the small ring and then again on a charity ride, (which has become a race over the years between myself and 2 others, more fun than anything really) last month when I could "feel" their presence so I flicked down for a climb and.... then came the shout of "dropped chain, bad luck" as they tore past! The moral is, chains only drop when you really, really don't want them to.

redmaxi · 17-04-2010 09:48AM

The angle is adjustable with braze on also or at least it should be.
The correct angle is vital to proper shifting. I usually find the crank arm should come very close to the front shifter in the farthest out position.

victorcarrera · 17-04-2010 12:25PM

Check these.
Are all components the same speed (spacing)?
Adjust high and low stops to manufacturers spec.
You should be using a curved washer with a braze on derailer to allow correct alignment with chainring and 1mm height.
Are chainrings compatible (with each other), not buckled and fitted correctly. If not the chain could be dropping on to the tops of the teeth on the small ring and hopping off.
If any adjustments are out, you are more likely to drop the chain when front downshifting if the chain is on the biggest rear sprocket.

Try this.
When down shifting, press rather than flick the "B' lever and soft pedal (but dont allow the chain to go so slack that you are relying on the derailer spring to keep tension on the top run of the chain.

72hundred · 17-04-2010 02:04PM

lescol wrote: »

The moral is, chains only drop when you really, really don't want them to.

Haha, yea!

Lumen · 26-04-2010 09:52PM

Well I think I found the cause of my chain drops, and it was screamingly obvious - a bent chainring tooth, hiding under the crank.

Pliers to the rescue!

How many links in your chain?

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