RBR reader Andrew K. wrote us recently about a topic that rings true for many of us as we get older but still want to be able to do the “big rides” we’ve done for years.
Andrew wrote: “As I age, I feel the need to go from a mid-compact to compact gearing to participate in some gran fondos. Would you consider discussing changing chain rings and implications for needing to adjust the derailleur, chain, etc? I specifically use a Shimano Ultegra Di2 11-speed groupset.”
Going from a mid-compact to compact gearing may not be as complicated as you think it might be, Andrew.
The fact that you have the Ultegra Di2 group is great for what you want to do, because your Ultegra crankset should be Shimano’s newer 4-arm design. One of its chief advantages is being able to accept many different chain ring combinations.
So, if you’re running the mid-compact 52/36 rings now, you can just remove them and put on the 50/34 to lower your gearing a bit more for those hilly gran fondos.
And, since there is only a 2-tooth difference between a 36- and 34-tooth chainring, there’s a good chance that you won’t have to change your chain length.
So, I would buy the new rings, install them and then check the chain when you are on the new 34 and the smallest cassette cog in back. As long as the chain is not now rubbing on the rear derailleur pulley – which would mean you’d likely see some slack in the lower run of chain beneath the chainstay – the chain length is fine.
If the chain does sag and is so loose it hits the pulley, you might be able to tighten the B tension screw – the one on the back and top of the derailleur that points to the rear. Tightening that adjustment screw pulls the derailleur back and increases chain tension and can take a little slack out – sometimes just enough for a small change in chain ring size like this.
If the B tension screw doesn’t solve the issue, then you will need to slightly shorten the chain. Usually, removing an inch of chain is enough – (which is one full link). To do that on a Shimano chain, you’ll need a chain tool and a special Shimano chain pin to reconnect the chain after you remove the links. Or you can use a master link instead of the chain pin, in which case you would remove two links, replacing one with the master link.
All these things are easy to do at home as long as you have the tools. I hope this gets you on the road with some nice low gears.
Regarding Shimano hollow pin chain and master link: I use it. But, my LBS mechanic cited it as an ‘unhappy’ combination and the source of some chain noise. Opinions?
I am using KMC Missinglink 11 master links with Campy Chorus chains and find that there is a slight noise as the chain wears. It manifests as a barely audible/felt “clunk” as the chain wraps the chain ring. I know it is chain ring related because I get a very mild clunk, then a firmer clunk on the next revolution of the cranks, then a mild clunk on the next revolution of the cranks, then nothing for 2-3 revolutions, then repeat. It took me a while to figure all that out but I’m sure that nobody else can hear it and I just accept it as the price paid for the convenience of a master link instead of the very expensive Campy chain tool. Replacing the link with a new one doesn’t change anything, so it seems to be an interaction of the link with the slight elongation of the chain as it wears.
If you need a lower gear because the hills are too steep, a two-tooth difference in chainring size will not be enough of a change.
A two-tooth difference is the finest of fine tuning. That’s only a six percent difference on a 36-tooth chainring. I believe most people would have a tough time saying which was which in a controlled test.
How much difference does a tiny shift like that make? We can put that in context by recalling the half step gearing that was commonly used on touring bikes in the 1980s. A common half-step arrangement had a small granny chainring, plus two big rings five teeth apart. 32/49/54 is an example, and it’s what’s on my 1981 Santana tandem. I have similar gearing on many single bikes. In this example, shifting between the two large chainrings gives you a 10 percent difference.
Basically, you can barely feel the five-tooth/10 percent difference. What it’s good for is the long slog — you’re on a constant grade for the next hour and the wind shifts slightly. You make that five-tooth shift, perhaps in combination with a rear shift, and the gear more perfectly matches the exact effort level you want to put out. And when an actual hill appears, you shift a cog or three in the rear, giving a much bigger change in gearing.
What’s missing from this discussion is gear inches. What you want is the right gear, as measured in gear inches, and chainring size is a means to the end, not the end itself. If Andrew has a 41-inch gear (36-24) and he really wants easier going on steep climbs, I’m going to guess that he’ll be far happier with a 30-inch gear (36-32).
If you are using the Di2, are you using synchronized shifting? If not, it’s worth looking into whether you can – it automatically shifts the front gear while you just shift the rear gear and you can have different settings when you are going up gears or down and use a smart phone app from the e-tube project for immediate updates.
There’s a Syncro Shift article in today’s issue.
I moved to using a KMC master link a year or so ago (on Ultegra 10-speed chains) and have had no issues with noise or otherwise. In fact, I just replaced a chain a week ago after getting about 20% more wear than normal out of it (not necessarily related to the master link; the point is, it certainly does not shorten chain life).
I wish I’d gone to a master link years ago: It makes replacing the chain much easier, and if you ever need to take the chain off for any sort of repair, that, too, is far, far easier. The only time I’ve ever had a chain issue was from an improperly inserted chain pin. Even with a robust Park Chain tool, it can still happen. And with a lesser tool, it’s even more likely.
I have not had a chance to try Shimano’s new chains with the Shimano master link yet, Dave, so I can’t comment. Hopefully some rider who have will.
I know it’s not recommended but I run a Di2 52-34 front with 11-30 rear and it works great, no shifting problems at all. A riding buddy of mine runs a 11-32 on the rear. Just my experience.
Thanks, John!
Another way to think of this is in terms of how much your cadence would change. Let’s say you’re climbing at 60-70 rpm. If you could magically drop from a 36 to a 34 during that climb, your cadence would increase by 6%, or about 4 rpm. That’s probably on the threshold of noticeable.
Thought of in terms of riding at 90 rpm, a 5% change in gear ratio means about 5 rpm. And 5% is about 3 teeth difference on the big ring, 2 teeth on the small chain ring, and one tooth on the cassette. As John points out, if you’re struggling on a hill, 5% will help, but only a little bit.
I’ve got the opposite problem, have a DuraAce 7900 10-speed compact, and want to go to 52/36 or 53/39 so that I don’t spin like a madman during sprints and downhills. As it’s 10-speed, is my only choice to find one used? Thanks
You probably will also want to lower your front derailleur.
Thank you for the article and answers to my question. I am glad this query generated so much discussion and the comments extended the discussion to cassette gearing, as well. I appreciate the quantitative analysis from experienced individuals.
I’m kind of on the cusp of being able to complete the particular ride that gives me the problem. I know a third approach would be more training to make my body more capable; thanks for not rubbing that in.
Again, thank for the technical input on the equipment aspect, and “Go Premium!” to keep this site active.
By coincidence, my LBS just last week completed this same conversion on my 10-speed Specialized Tarmac. I was riding local climbing challenge Mt. Diablo recently with the old set up, and decided half-way up that at the age of 59, I deserved to make things a little easier! My LBS owner tried to convince me to go 52-34, i.e. just change the smaller chainring, but I was concerned about shifting efficiency. I had him convert to the standard 50-34 compact set up, and retained the 11-28 cassette.
Based on two tough climbs I’ve done since, I’d say there is a significant difference. Both have 2-3 sections where I’ve had to stand up in the the past, but i’m now able to complete both climbs seated, thereby saving my legs and my lungs. This was essentially my goal, so I may have biased the outcome but, regardless, I’m glad I made the switch.
Incidentally two chain links were removed in the process, although judging from the article, one or none might have done the job.
My immediate reaction is exactly the same as that of John Schubert. I would add that if you are going to do it anyway, then the simplest (and cheapest) solution would be to replace only the inner chainring. That obviates the need to move the front changer down.
Also, assuming that you’re using a five-arm 110mm BCD chainset, you may as well fit a 33-tooth chainring instead of a 34.
For your lame, injured, fat, old, and out of shape riders who live where there are hills, perhaps you could have an article about converting from a compact crankset to a triple. I have only ever had triples because they offer a wide range of normal gearing, plus that granny for when the going gets just too tough.