Lloydb

I知 just getting back into cycling with my first new bike to replace my 9 speed Campy Record. I ordered my new (Marinoni Piuma Ti) with Record components, and a compact crankset. I enjoyed unpacking it and tuning it up but I知 wondering if the chain is too long? It痴 sitting on the chainstay while resting in its lowest gears. I知 wondering if that might be why I知 having trouble getting the shifting right.

Buzzkill53120

Was the bike assembled or partially assembled when you received it? Sounds like the chain needs to be shortened. Park Tool has a video on how to properly size up a chain.

Bill Kapaun

IF the chain is "drooping", either too long or the chain wrap capacity of the RDER is exceeded.
How much slack can you generate when on BIG:BIG?
This is the method I use for a simple check.
Normally, we want more than 1" and less 2".

bldegle2

A very simple way to get it right. Small ring up front, smallest ring in da rear. The chain length is determined by one simple thing, just long enough that the chain does not rub the rear derailleur arm. I will post a pic later, got to run right now...

dsbrantjr

Better be sure it is long enough to easily go on big-big or you are in for an unpleasant surprise one day.

Marcus_Ti

It would be. Small/small sizing optimized for the longest chain possible your derailleurs support. As opposed to big/big that optimizes based on the shortest possible chain size for the given cogs.

bldegle2

^^^^^^thank you, what he said....^^^^^^^^

Lloydb

Your responses tell me I was on the right track. The bike came just partially disassembled, the drive train was complete. However, I asked for a compact crank, I assume that would require a shorter chain as well? Maybe that wasn稚 installed/shortened. Thanks!

HerrKaLeun

Look up the manual for that rear derailleur.

andrewclaus

This method works for an average triple crank, not so well for doubles. Not for my gravel bike, for instance.

bldegle2

I build all my rides up from bare frames. I run a 50/33 (special ring made in France for 5 bolt 110 BCD) and a 11/34 in da rear. As long as you don't go way out of spec with the rear derailleur and cassette, it works all the time. What you are looking at is a medium cage 4600 derailleur rated for 30 max, runs the 34 like a dream. Same for my other unit, same specs (50/33, 11/34), running a 4700 rear derailleur rated for 32 max, but sporting a 11/34 also. Both are medium cage (GS)....if I make the chain the next size longer the derailleur arm will rub the chain as the end/tip will be higher and interfere with the chain...

HillRider

Not necessarily. If the gearing exceeds the rear derailleur's chain wrap capacity, then having no slack in small-small could give a chain too short to allow big-big. I've done that on several bikes since I run triple cranks and replace the OEM 30T granny chainring with a 26T. Small-small is too slack to use but big-big is still functional. There is really never any need for small-small or big-big but big-big can be selected inadvertently and must work.

This situation is unlikely on a new bike set up by the manufacture but it can be done.

DaveSSS 

Be careful if the chain is a Campy 10, 11 or 12. All use a special joining pin that requires a Campy tool to install. If the chain must be shortened, you can't just push out a pin and reinstall it, like you could with 9 speed. Although Campy doesn't make a quick link, there are other brands that will fit and work. I remove the original joining pin and the pin next to it, on the same pair of outer plates, then use the quick link to join it.

jadocs

Sounds like the bike is in all kinds of disarray from the manufacturer. Before sizing your chain correctly, make sure the b-limit screw is set correctly. I advise you to visit park tool YouTube channel and watch everything associated with rear derailleurs (setting, adjustment/indexing) and chain sizing.

and yes the small/small chainsizing technique does work. This assumes correct cassette/derailleur compatibility (manufacturer should not be sending a bike with a cassette that is incompatible with the derailleur) and correct b-limit adjustment.

TiHabanero

"Better be sure it is long enough to easily go on big-big or you are in for an unpleasant surprise one day."

Yep, be real sure of this. My former boss snapped the chain stay on his custom carbon frame by not checking this and then shifting into the big ring while on the largest diameter sprocket out back.

bldegle2

That is what bike stands are for. Always run though the gears before you get it outdoors in the wild....

squirtdad

here is a good vid for small/small sizing...... i have used this successfully with both 105 5800 compact 50/34 11/32 setup and vintage 52/39 12x28 setups

alcjphil

I assume by this that the top run of your chain is either touching or very close to the top of the chainstay when it is located on the small chainring and the smallest rear cog. Is the chain visibly sagging along that top run? If it isn't then this condition is normal and that gear combination is one that you would almost never use normally. It would surprise me if the people at Marinoni would not know how to properly size a chain. I have dealt with the staff at Marinoni many times and have always found them to be very knowledgable. Several times I have taken Ergopower shifters in and had them overhaul them while I waited. However, if you have a 34 tooth small chainring and an 11 tooth small cog the chain is bound to be very close to the chainstay on a bike like your Piuma.

Lloydb

The bike manufacturer had me remove the “B Link” and make a few adjustments. It’s all good, chain length was fine! Been enjoying it for a month now, and realized I should close this out. Thanks guys!