small/small chain sizing
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small/small chain sizing
I have always done big/big and add 2 links chain sizing.
with my recent build with 5800 105 with a compact crank (50/34) and 13/32 cluster, the result was not as good as I wanted in terms of shifting and rear derailler position
My mechanic suggested trying low/low saying that it is shimano's current technical reccomendattion
it worked great for me, not sure how it would work with vintage deraillers and crank/cluster sizing, but will try soon
this method if you are not familiar with it (and I wasn't) is:
put deraillers in low/low combination
thread the chain thru the deraillers and have on the low rings and teeth
size the chain so that it does not rub on rear derailer
here is a video link
ymmv
with my recent build with 5800 105 with a compact crank (50/34) and 13/32 cluster, the result was not as good as I wanted in terms of shifting and rear derailler position
My mechanic suggested trying low/low saying that it is shimano's current technical reccomendattion
it worked great for me, not sure how it would work with vintage deraillers and crank/cluster sizing, but will try soon
this method if you are not familiar with it (and I wasn't) is:
put deraillers in low/low combination
thread the chain thru the deraillers and have on the low rings and teeth
size the chain so that it does not rub on rear derailer
here is a video link
ymmv
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I can see how this would work. But I can't yet see the advantage over my current method: big (front) - small (rear) and vertical cage. This works for me, as long as I respect the chain wrap limits of the RD.
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Putting the chain on the smallest chainring and smallest cog to size the chain is how I learned to do it, I've never done it any other way. For many years I didn't know some people did it differently. It works for me on my vintage bikes with 42T small rings and modern bikes that have compact cranks.
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This should work, unless you're intentionally exceeding the recommended chain wrap capacity. Some derailleurs will allow their stated capacity to be exceeded, others don't.
I would just caution you to shift into the big chainring, and carefully work your way up to the big cog in the back, checking that the chain length allows that combination without exploding.
I would just caution you to shift into the big chainring, and carefully work your way up to the big cog in the back, checking that the chain length allows that combination without exploding.
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This should work, unless you're intentionally exceeding the recommended chain wrap capacity. Some derailleurs will allow their stated capacity to be exceeded, others don't.
I would just caution you to shift into the big chainring, and carefully work your way up to the big cog in the back, checking that the chain length allows that combination without exploding.
I would just caution you to shift into the big chainring, and carefully work your way up to the big cog in the back, checking that the chain length allows that combination without exploding.
Ben
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the long accepted general best practice (at least as explained to me) was - as short as possible but no shorter.
so - use the small small cog combination, make the chain the shortest possible length that it is not sagging (that is, the jockey cage is just starting to take tension) and then set the chain at that length. Run thru the various cog / chainwheel combinations and confirm that you have enough chain and that shifting is good. Sometimes too much chain tension will inhibit shifting to a smaller cog. On triple chainrings you may not be able to use the combinations of large ring / large cog.
No one rule covers all possibilities, but this approach yields good results in most cases.
Mark Petry
Bainbridge Island, WA USA
so - use the small small cog combination, make the chain the shortest possible length that it is not sagging (that is, the jockey cage is just starting to take tension) and then set the chain at that length. Run thru the various cog / chainwheel combinations and confirm that you have enough chain and that shifting is good. Sometimes too much chain tension will inhibit shifting to a smaller cog. On triple chainrings you may not be able to use the combinations of large ring / large cog.
No one rule covers all possibilities, but this approach yields good results in most cases.
Mark Petry
Bainbridge Island, WA USA
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The real risk is when the chain is actually too short to fit around the chainring and the rear cog, and the results can be severe. Trashed RD, bent/broken derailleur hanger, and broken rear spokes - and worse - you winding up on the ground.
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#9
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the long accepted general best practice (at least as explained to me) was - as short as possible but no shorter.
so - use the small small cog combination, make the chain the shortest possible length that it is not sagging (that is, the jockey cage is just starting to take tension) and then set the chain at that length. Run thru the various cog / chainwheel combinations and confirm that you have enough chain and that shifting is good. Sometimes too much chain tension will inhibit shifting to a smaller cog. On triple chainrings you may not be able to use the combinations of large ring / large cog.
No one rule covers all possibilities, but this approach yields good results in most cases.
Mark Petry
Bainbridge Island, WA USA
so - use the small small cog combination, make the chain the shortest possible length that it is not sagging (that is, the jockey cage is just starting to take tension) and then set the chain at that length. Run thru the various cog / chainwheel combinations and confirm that you have enough chain and that shifting is good. Sometimes too much chain tension will inhibit shifting to a smaller cog. On triple chainrings you may not be able to use the combinations of large ring / large cog.
No one rule covers all possibilities, but this approach yields good results in most cases.
Mark Petry
Bainbridge Island, WA USA
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I don't agree with this, provided that your RD has sufficient chain wrap capacity. With proper capacity and chain length, the RD will handle any possible combination of front chainrings and rear cogs. There may be cross-chaining issues, but those can avoided by choosing different gears. Cross-chaining should be avoided, but it should not be catastrophic if you do it enroute to a different gear.
The real risk is when the chain is actually too short to fit around the chainring and the rear cog, and the results can be severe. Trashed RD, bent/broken derailleur hanger, and broken rear spokes - and worse - you winding up on the ground.
The real risk is when the chain is actually too short to fit around the chainring and the rear cog, and the results can be severe. Trashed RD, bent/broken derailleur hanger, and broken rear spokes - and worse - you winding up on the ground.
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yes, you are right, with a long enough cage and careful selection of chain length, you MAY be able to get the chain to wrap the large / large or small / small combination on a triple, but why ? Both are at the extremes of chain tension and slack, and also friction and wear associated with cross-chaining are at a maximum, but more importantly, the gear ratios of both combinations can be approximated by less extreme selections of ring and cog.
I have only one bike with long derailleur cage, it can easily shift the large large, but I never ever use that combination, or the small small either. Sort of a department store bike anyway as you can see :- )
Mark Petry
Bainbridge Island, WA USA
I have only one bike with long derailleur cage, it can easily shift the large large, but I never ever use that combination, or the small small either. Sort of a department store bike anyway as you can see :- )
Mark Petry
Bainbridge Island, WA USA
#12
don't try this at home.
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If using your small-small method, I'd carefully check the big chainring - biggest cog combo before riding it. The chain needs to be long enough to not jam when shifting into the big-big.
I sized using the usual "big-big + 1 inch" method, and it was fine. Like previous comments mentioned, this might be best if you are exceeding the recommended cassette sizes.
A rider might never want to use the big-big, especially on a triple, but it's easy to lose track of the current gear, and shift to the big-big by accident.
I sized using the usual "big-big + 1 inch" method, and it was fine. Like previous comments mentioned, this might be best if you are exceeding the recommended cassette sizes.
A rider might never want to use the big-big, especially on a triple, but it's easy to lose track of the current gear, and shift to the big-big by accident.
#13
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The big/big method works most of the time, but on occasion it's less than optimal.
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I don't agree with this, provided that your RD has sufficient chain wrap capacity. With proper capacity and chain length, the RD will handle any possible combination of front chainrings and rear cogs. There may be cross-chaining issues, but those can avoided by choosing different gears. Cross-chaining should be avoided, but it should not be catastrophic if you do it enroute to a different gear.
The real risk is when the chain is actually too short to fit around the chainring and the rear cog, and the results can be severe. Trashed RD, bent/broken derailleur hanger, and broken rear spokes - and worse - you winding up on the ground.
The real risk is when the chain is actually too short to fit around the chainring and the rear cog, and the results can be severe. Trashed RD, bent/broken derailleur hanger, and broken rear spokes - and worse - you winding up on the ground.
Now I have run setups that had the RD completely folded back and the chain rubbing on itself running the small-small. (Triples) That combo only gets used for when long hills level out and I do not want to do a double shift, then have to reverse that double shift as soon as the hill steepens again. Never had an issue beyond the noise. Now, with more modern cranksets with their pegs and pickup teeth, usually I cannot even run the small-small without the bigger ring picking up the chain so it isn't even an issue.
Ben
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Makes sense. When I was running my bike's original 52/42 chainring and 13-24 freewheel, I cut the chain to suit.
After switching to a 50/39 chainring and 13-25 freewheel, the chain rubs the rear derailleur cage in the small/small combo -- 39T chainring, 13T freewheel cog. I suppose I could cut a link or two but haven't bothered. I just avoid that gear combo.
Main problem with the chain being a link or two too long is the chain slop-slap on downshifts -- occasionally the chain drops, but instead of fixing it I just jockey the front derailleur lever to pick up the chain again while riding. So far, so good, although it can be unnerving on hill climbs in traffic -- I have only a couple of seconds to reset the chain before I run out of momentum.
After switching to a 50/39 chainring and 13-25 freewheel, the chain rubs the rear derailleur cage in the small/small combo -- 39T chainring, 13T freewheel cog. I suppose I could cut a link or two but haven't bothered. I just avoid that gear combo.
Main problem with the chain being a link or two too long is the chain slop-slap on downshifts -- occasionally the chain drops, but instead of fixing it I just jockey the front derailleur lever to pick up the chain again while riding. So far, so good, although it can be unnerving on hill climbs in traffic -- I have only a couple of seconds to reset the chain before I run out of momentum.
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If using your small-small method, I'd carefully check the big chainring - biggest cog combo before riding it. The chain needs to be long enough to not jam when shifting into the big-big.
I sized using the usual "big-big + 1 inch" method, and it was fine. Like previous comments mentioned, this might be best if you are exceeding the recommended cassette sizes.
A rider might never want to use the big-big, especially on a triple, but it's easy to lose track of the current gear, and shift to the big-big by accident.
I sized using the usual "big-big + 1 inch" method, and it was fine. Like previous comments mentioned, this might be best if you are exceeding the recommended cassette sizes.
A rider might never want to use the big-big, especially on a triple, but it's easy to lose track of the current gear, and shift to the big-big by accident.
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#17
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Oh, yes. That department store with only one department: the nice bike department.
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yes, you are right, with a long enough cage and careful selection of chain length, you MAY be able to get the chain to wrap the large / large or small / small combination on a triple, but why ? Both are at the extremes of chain tension and slack, and also friction and wear associated with cross-chaining are at a maximum, but more importantly, the gear ratios of both combinations can be approximated by less extreme selections of ring and cog.
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I think one needs to review both, plus the shifting performance, with B screw rear mechs, that can come into play too.
With other when expanding the range, a few rear derailleurs allow multiple positions for the jockey cage, that can sometimes help or be needed.
I just did that to a Nuovo Record rear mech when I went beyond the limits of the front chainring differential, 50/34
With other when expanding the range, a few rear derailleurs allow multiple positions for the jockey cage, that can sometimes help or be needed.
I just did that to a Nuovo Record rear mech when I went beyond the limits of the front chainring differential, 50/34
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I just installed a FSA Vero 50/34 on my Criterium Series. Thank you for a timely article.
#21
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The little/little method will work with doubles or triples and gives the longest possible chain within the RD's wrap capacity. I've used the same chain length on doubles and triples, because the longer cage on the triple takes up the slack in the little/little position. There is no advantage to using a shorter chain. The only time the big/big method is a must, is when the largest cog being used is larger than recommend for the RD cage length. Then you better add length and know that the chain may hang loose in the little ring and several of the smaller cogs. It takes 4 teeth larger to use 1 inch of additional chain length.