Triple chainrings: a flawed concept/design?

Triple chainrings are, as we know, found on all kinds of bikes, including electrified bikes like mine. But the topic I wish to broach applies equally, I think, to both categories. And it actually arises out of my biking experiences prior to doing my electrification projects.

My enagement with bicycles dates way back, prior to the appearance of 6-cog freewheels (5 was max when I first got seriously involved). I was avidly tinkering with bikes, doing a bit of amateur racing and some cross-country touring back then. About the time I took a break from the bike world was when mountain bikes were first appearing on the scene. Though I built my own mountain-ish bike using an old Schwinn Continental frame (it provided the widest tire clearance of any semi-decent frames I'd run across), triple chainrings were not commonly available in my area. So I got by with just 12 gears on that bike.

Jump ahead to around the turn of the last millennium when I got involved in bicycling anew, and triple chainrings were on just about everything. So when it came time to acquire bikes again, a triple chainring was of course something I wanted to have. But in actually using triple chainrings over the course of the last decade or so, I've come to view them as almost more of a design flaw than as an advancement. I figured I might explain here my reasoning in hopes of getting feedback from those more expert than myself--just in case it may be my own thinking or practice that is somehow flawed. I ride almost exclusively on paved roads, by the way, and most of those miles are on a recumbent tandem.

So of course the appeal of the triple chainring is the low gearing it affords. Great for going up inclines, especially steep ones. But that's where the problems come in and where the triple chainring fails to live up to its promise. That's because, once I'm going up that incline and am reaching speeds slow enough to warrant the lower gears, there is already maximal tension on the chain: when the chain is under that sort of tension, the front derailleur can't derail the chain onto the smallest chainring. I would have to pause, then resume, pedaling, for the desired gear changing to work under that scenario. That would effectively mean coming to a stop. So why even have that small chainring if it can't be pressed into service when most needed?

So, in my experience to date, the only way the small chainring can ever come into play is if I remember to shift down to it prior to starting the climb. If I forget to do that or happen not to know ahead of time how steep/long the incline is, then I am simply forced to climb it in the lowest possible gear I can get on the middle chainring. Thus, my working assumption that triple chainrings are at best over-hyped, and at worst simply a flawed design solution.

Am I wrong in any way my suppositions? Do I need better front derailleurs, or do I need to work on making finer adjustments to them? Input will be appreciated.

Which model gearset do you have ?
Most decent gearsets will change under load, the better ones certainly will, but most riders learn to subtly reduce the chain tension momentarily whilst shifting, to minimise strain and wear on the gears and chain.

I believe Sram/Shimano components--I'd have to double check to give particulars. I've actually got 3 recumbent tandems, all with slightly differing components, and the shifting problem referenced applies to all 3. If the subtle pedal-cadence adjustment you speak of is the solution, that will be very diffcult to coordinate on a tandem. I'll probably test it out at some point here though to see. I'm sure it will make for a tense moment since, at such slow speeds (e.g., 6 mph) on a steep incline any reduction in momentum gives the sensation that tipping over is imminent.

for sure tandems and recumbents have their own set of complications, but a good set of components, correctly set up, should have no problem shifting under power.
I doubt you and your partner combined generate the kind of pedal power a Tour level pro cyclist does on a climb, and they couldnt tolerate unreliable shifts.
It may just be set up/fine adjustment, or you may have to source more appropriate components, but there are solutions.
is this only the front chain ring, when shifting to the smaller sprockets ?... i would expect more issues shifting up the sprocket sizes on the rear cassette.

Hillhater said:

is this only the front chain ring, when shifting to the smaller sprockets ?... i would expect more issues shifting up the sprocket sizes on the rear cassette.

Click to expand...

Yes, none of the three will shift to the small chainring when the chain is under the tension of climbing a hill. On the first tandem I thought maybe there was some misadjustment so I took it to the shop where I'd bought it. They worked on it and supposedly adjusted it, but it never worked reliably: the only way to to unfailingly shift onto the small chainring on any of those bikes is to do it while the chain is under little or no tension. If it's not done then, it's unlikely to work at all--only a loud dragging of the chain against the derailleur frame results from an attempt to shift onto the small chainring.

Actually, I need to qualify that: if the chain happens to not be already on the largest cassette cog, I have seen the chainring shifting work once the rear derailleur moves the chain onto one of the other rear cogs. Problem with that strategy is that it doesn't always work and, even more importantly, I'm almost always already in my lowest gear in the middle chainring at the time I need to shift to the small chainring. Thus, my conclusion that the design is faulty. Or maybe faulty when it comes to bikes with unusually long shift cables--though the rear derailleur shift cable is yet longer and I've had no issues with its operation.

Remember the rear derailier is shifting on the slack side of the chain run, so doesnt have to work against chain tension which the front shifter does have to work against...but shifting down to smaller sprockets should not be too difficult.?
Shifting up to the bigger sprockets is not an issue ?

For a properly maintained drivetrain, it takes only a fraction of a pedal strokes time to shift to a smaller chainring. You ease up only for as long as needed.

But the heart of the matter is that you really should be planning ahead and getting into the small ring before you need to use it, when you can more easily afford to pause the pressure on the pedals. This is part of what goes on in a race situation. You see or know a steep climb is coming and you drop to the small ring before you've slowed and before you are on the incline.

You are right that triple chainrings are not needed for most types of riding, especially with new 2x9/10/11 systems giving a wider range.

Hillhater said:

Shifting up to the bigger sprockets is not an issue ?

Click to expand...

I've never had a problem shifting onto the large chainring on any of these bikes (well, except for an isolated incident where I had misadjusted the derailleur and wound up overshifting [chain fell off the crank arm side]). Another factor all these bikes have in common is, of course, chain length. These chains are all about twice as long as chains on typical upright bikes. Could that be a factor?

I've got an upright, non-electrified errand bike that has a triple chainring. I very, very rarely use the smallest chainring (40/32 is the lowest ratio on the middle chainring which, on a 26" wheel, is as low as any of the roads on which I ride require). But I don't recall ever having had any issue shifting onto the small chainring on that bike. Though surely such shifting would not have taken place under high chain tension. That bike is currently sidelined for maintenance, but I now want to get it going soon so I can try shifting to the small chainring under load on it to see what results I get on it.

Well,, as usual just a guess, but I bet the chain line on those tandems is subtly different from that on other bikes, such as MTB's. Something is making it want to stay on the middle ring. My own experience is that the chain tends to want to bounce down to the low gear, sticking on the top or the middle only if the derailleur keeps it there.

You are not suppose to shift the front sprocket under load. If you're shifting under load, you're just doing it wrong. They are not designed to shift that way. You'll bend your front derailleur, wear out the sprocket ramps and teeth, stretch the chain, and under the right conditions, can fold the sprocket or even snap the chain.

Over many yrs, ive always had good luck with the 3xs chainring.. but took it fairly easy on them,i always build my ebikes to do what i need them to do,i have monster hills and a single front ring + 9 gear rear is all i use but my top sp is only 28mph.