53/39 or 52/36 chainrings?

Triathlon Forum
1

I’m currently running 52/36 rings on my TT bike (with an 11-25 cassette), Ultegra crank w/standard Ultegra rings not aftermarket, and am wondering if there is any compelling reason not to change up to 53/39 rings?

I run 53/39 on my road bike with an 11-28 cassette and it’s fine for everything including racing. Started with Compact, then Mid-Compact and wound up with Std 53/29 and am a happy camper.

I’ll use the same bike for Tri as well once I get some more swim training in, and if there’s a hilly course, swapping on an 11-28 cassette is quick and easy.

I’m not anticipating needing extra hill-climbing help from smaller chainrings on the TT/Tri bike, so it would seem to make sense to go with 53/39 for greater top end range. I found the 39 much more useful, a more satisfying operating range, than the 36 on my road bike.

I searched for threads on this, and didn’t find a previous discussion (apologies if I missed it, and this is rehashing an already popular topic).

Thanks for your insights.

2

…it would seem to make sense to go with 53/39 for greater top end range.

Difference in “top sustained speed under power” (i.e. speed at 100 rpm) is 0.7 mph (37.7 vs 37.0). Honestly, its a pretty small window of circumstances where you’d spin out a 52 but not a 53. One scenario I modeled suggested the 53 is only helpful, relative to the 52, on grades between -4.5% and -4.75%. Any more slope, and you’re spun out on both. Any less, and the 52 is enough. Depending on your .cda, .crr, and atmospheric conditions, the #'s may move up or down, but the range between the two is always going to remain similarly tight.

If you were starting from scratch, were choosing between a 52 and a 53, and were supremely confident you could tackle any incline with a 39T front chain wheel, you might consider the 53. But I see no compelling reason to switch to a 53 if you already have a 52.

3

If you are a reasonably strong cyclist then do it.
I run a 54/39 on my TT bike and 53/39 on my roadie. Both with 11-28.

I have never felt under-geared for anything except the Alpe d’huez triathlon which had 3000m (10,000ft) of climbing in 120km (75 miles).

The 54 on the TT bike is good as I tend to grind a lower cadence.

52/36 is ok if you are a bit weaker cyclist.

4

…it would seem to make sense to go with 53/39 for greater top end range.

Difference in “top sustained speed” (i.e. speed at 100 rpm) is 0.7 mph (37.7 vs 37.0). Honestly, its a pretty small window of circumstances where you’d spin out a 52 but not a 53. Once scenario I modeled suggested the 53 is only helpful, relative to the 53, on grades between -4.5% and -4.75%. Any more slope, and you’re spun out on both. Any less, and the 52 is enough.

If you were starting from scratch, were choosing between a 52 and a 53, and were supremely confident you could tackle any incline with a 39T front chain wheel, you might consider the 53. But I see no compelling reason to switch to a 53 if you already have a 52.

Thank you, good to see the numbers between the big rings. Matter of fact, I really only noticed a significant improvement in operating range on the 39 inner ring on my road bike, can’t say I noticed much on the big ring. And on a TT/Tri bike, the inner ring isn’t such a factor unless it’s a hilly course.

I’m ordering a complete PM crankset, so it’s just a choice between those two chainring options. Hmm…maybe a good call to get the 53/39, so that way I’d have it on the PM crankset, and if I ever needed to swap to smaller rings for the odd hilly course, I could rob them from the other crank.

5

52/36 is ok if you are a bit weaker cyclist.

:slight_smile:

I run a 52/36, but also like to spin. So I can pedal my 52/11 at 110-120 rpms before coasting at 42mph. And having a 36/28 up mountains is great to keep my cadence above 70.

6

I’m ordering a complete PM crankset, so it’s just a choice between those two chainring options. Hmm…maybe a good call to get the 53/39, so that way I’d have it on the PM crankset, and if I ever needed to swap to smaller rings for the odd hilly course, I could rob them from the other crank.

As long as the PM accepts the 4 arm shimano rings. Personally I like these since you can put whatever ring size on the chassis and not have to deal with the 110 to 130 BCD change that 52/36 and 53/39 will come with.

7

Try riding your current setup without ever shifting into the 25. Meaning 36/23 is your easiest gear. If you’re good with that, then 39/25 is a very similar gear ratio and you’ll be fine. Of course you always have the option of moving to a 11-28 cassette for hilly days, which is slightly easier than 36/25, but I’m not sure if you want to go through the hassle of spending money on bigger chain rings just so you can also give yourself the hassle of swapping cassettes.

So assuming the bail out gear isn’t a problem for you, nor is the cost of new rings, then you should move to 53/39.

You’ll gain more top end gear for downhills
You’ll be using larger ring/cog combos which are more efficient than smaller ring/cog combos
You’ll have better ability to stay in your small ring without cross chaining on climbs that have sections that flatten out.
You’ll have more reliable/quicker/smoother shifting performance in the FD due to a smaller gap in ring sizes.

8

If you are a reasonably strong cyclist then do it.
I run a 54/39 on my TT bike and 53/39 on my roadie. Both with 11-28.

I have never felt under-geared for anything except the Alpe d’huez triathlon which had 3000m (10,000ft) of climbing in 120km (75 miles).

The 54 on the TT bike is good as I tend to grind a lower cadence.

52/36 is ok if you are a bit weaker cyclist.

Lol, didn’t you hear that grinding it out is “out” in the pro peloton? High rpm climbing now. Low rpm is so past decades.

9

The question is highly rider and fitness dependent. You need to know what your cadence is when you are highly fatigued.

For me, in 40k TT my cadence often drops down into the 70rpm range just to maintain my power numbers to the finish. If I had too small a chainring, then I wouldn’t be able to maintain the wattage.So I keep a 54 on mine so I never run out of gears. Not to mention, I hate running in the 11 tooth back unless I absolutely have to as the chainline is not as straight.

10

If you are a reasonably strong cyclist then do it.
I run a 54/39 on my TT bike and 53/39 on my roadie. Both with 11-28.

I have never felt under-geared for anything except the Alpe d’huez triathlon which had 3000m (10,000ft) of climbing in 120km (75 miles).

The 54 on the TT bike is good as I tend to grind a lower cadence.

52/36 is ok if you are a bit weaker cyclist.

Lol, didn’t you hear that grinding it out is “out” in the pro peloton? High rpm climbing now. Low rpm is so past decades.

Good thing I’m not a pro cyclist.

11

Try riding your current setup without ever shifting into the 25. Meaning 36/23 is your easiest gear. If you’re good with that, then 39/25 is a very similar gear ratio and you’ll be fine. Of course you always have the option of moving to a 11-28 cassette for hilly days, which is slightly easier than 36/25, but I’m not sure if you want to go through the hassle of spending money on bigger chain rings just so you can also give yourself the hassle of swapping cassettes.

So assuming the bail out gear isn’t a problem for you, nor is the cost of new rings, then you should move to 53/39.

You’ll gain more top end gear for downhills
You’ll be using larger ring/cog combos which are more efficient than smaller ring/cog combos
You’ll have better ability to stay in your small ring without cross chaining on climbs that have sections that flatten out.
You’ll have more reliable/quicker/smoother shifting performance in the FD due to a smaller gap in ring sizes.

That’s another great point, shifting reliability/quickness.

Your note about more efficient with larger ring/cog combos, are you referring to less friction due to larger radii? That’s also an interesting one. I understand it in theory, not sure if I’d ever recognize a difference, but interesting nonetheless. I read some of the testing of larger jockey wheels and it didn’t seem definitively better, but in the case of chainrings, if the bigger set might save watts, why not. :smiley:

12

This makes me feel like a putz… I’m on a 50/34 and I truly have not found a reason to go any bigger, I even run a 12-28 cassette on my setup! I did IMLP last year and was happy to have it. My average cadence is 88-92 - I could imagine having a 52/36 I guess haha…

When I ran the calculators it showed that a 50x15 @ 80 cadence would give me a speed of 20.97mph… That sounded fine to me based on my bike strength I had plenty of rpm to go in that gear or heck other gears to click into. A 50x12 @ 110rpm was 36mph so I see where it suffers there but I found the 50t to be way more suitable for the rest of most course I ride.

13

The question is highly rider and fitness dependent. You need to know what your cadence is when you are highly fatigued.

For me, in 40k TT my cadence often drops down into the 70rpm range just to maintain my power numbers to the finish. If I had too small a chainring, then I wouldn’t be able to maintain the wattage.So I keep a 54 on mine so I never run out of gears. Not to mention, I hate running in the 11 tooth back unless I absolutely have to as the chainline is not as straight.

I’m just starting TT’s, and had my first 20k two weekends ago (with no cadence sensor or power on my bike yet), so have no idea what my cadence avg or peak was. Only had HR, speed and elapsed time to go by on my Garmin, and RPE. That said, based on past Strava data in road racing and longer training rides, I’m in the 85-95 avg cadence range with peaks on laps or long segments in the 105-100 range while fatigued.

Looking at the past, with improved fitness, I tend not to increase cadence range, just run a slightly bigger gear at similar cadence. Not grinding, just going one cog smaller in the back and keeping my respiratory rate similar along with better fitness and output level that comes along with it.

14

You probably don’t need anything bigger than a 52 then unless your average speed is over 28mph or so.

15

Try riding your current setup without ever shifting into the 25. Meaning 36/23 is your easiest gear. If you’re good with that, then 39/25 is a very similar gear ratio and you’ll be fine. Of course you always have the option of moving to a 11-28 cassette for hilly days, which is slightly easier than 36/25, but I’m not sure if you want to go through the hassle of spending money on bigger chain rings just so you can also give yourself the hassle of swapping cassettes.

So assuming the bail out gear isn’t a problem for you, nor is the cost of new rings, then you should move to 53/39.

You’ll gain more top end gear for downhills
You’ll be using larger ring/cog combos which are more efficient than smaller ring/cog combos
You’ll have better ability to stay in your small ring without cross chaining on climbs that have sections that flatten out.
You’ll have more reliable/quicker/smoother shifting performance in the FD due to a smaller gap in ring sizes.

That’s another great point, shifting reliability/quickness.

Your note about more efficient with larger ring/cog combos, are you referring to less friction due to larger radii? That’s also an interesting one. I understand it in theory, not sure if I’d ever recognize a difference, but interesting nonetheless. I read some of the testing of larger jockey wheels and it didn’t seem definitively better, but in the case of chainrings, if the bigger set might save watts, why not. :smiley:

To be honest, I can’t tell you for sure that larger rings/cogs are more efficient. I’m not that smart, but I was going with the same assumption as you were that the less you have to bend the chain around tighter angles, the smoother it will run. It seems to be a “somewhat” generally accepted concept, but I don’t know if there is hard data to back it up when it comes to cycling and the difference of running 39/19 compared to 36/17. So take it for what it’s worth.

Frankly, I run 50/34. I don’t tri or TT anymore, but I never needed anything more than that along with an 11/25 cassette for any of the courses I did. Went as fast as 57:20 on a flat but windy 40k. Would have gone to 50/38, but I would swaped that crank between TT and road bike where I do need the extra climbing gears for hills that I didn’t do on my TT bike.

16

For me, in 40k TT my cadence often drops down into the 70rpm range just to maintain my power numbers to the finish. I

That’s looks like a sign of really poor pacing.

Cadence is a function of power.
Your power on a 40k TT should be fairly even for the duration.
Your slowing cadence says you go out too hard.

17

I notice a lot of newer TT bikes now cone with a 52/36 as standard off the shelf. I am surpirsed at this for a TT bike, I would have thought a 53/39 would have been more suited.
How does the 52/36 compare? Is it better all round?

18

I notice a lot of newer TT bikes now cone with a 52/36 as standard off the shelf. I am surpirsed at this for a TT bike, I would have thought a 53/39 would have been more suited.
How does the 52/36 compare? Is it better all round?

Almost ALL bikes come with 52/36 and 11-28 standard. I think it really picked up steam when Shimano went to 110BCD for all their cranks.
That combo offers a range of gearing applicable to most buyers.
That doesn’t mean it’s the optimal gearing

19

I notice a lot of newer TT bikes now cone with a 52/36 as standard off the shelf. I am surpirsed at this for a TT bike, I would have thought a 53/39 would have been more suited.
How does the 52/36 compare? Is it better all round?

Almost ALL bikes come with 52/36 and 11-28 standard. I think it really picked up steam when Shimano went to 110BCD for all their cranks.
That combo offers a range of gearing applicable to most buyers.
That doesn’t mean it’s the optimal gearing
Do you think you notice a lot of difference vs 53/39? Is it mainly top end? Can’t imagine spinning out unless hammering downhil And I suppose you have benefits of uphill.
None the less it seems an odd combo on a tt bike

20

I notice a lot of newer TT bikes now cone with a 52/36 as standard off the shelf. I am surpirsed at this for a TT bike, I would have thought a 53/39 would have been more suited.
How does the 52/36 compare? Is it better all round?

My personal opinion (YMMV) is that a 52/36, given no other options, is probably the most versatile chainring setup if you can’t run anything else on a road or TT/Tri bike. With that and an 11-28 cassette, you could pretty much handle 98% of the climbs you’d ever encounter, and the 52-11 can handle upwards of 52+ mph if my calcs are correct before spinning out, and that would be exceeded by a 53 by a couple of mph. I typically don’t go that fast, but maybe I’m just a wimp. I had a front blow out at 52 mph a couple years ago coming down out of a mountainous area, and it scared the you-know-what out of me, so I try not to go above 50 if I can help it. We are, after all, just wearing spandex, you know. :slight_smile:

All of that said, I switched from 52/36 to 53/39 on my road bike, because the 39 covers a much broader operating range, so I don’t have to shift into the big ring as often when in rolling terrain, love it. I guess it feels more familiar, because I was running a 42 small ring in high school and college.

Now, TT is different than riding the road bike, I’m in my big ring the entire time (at least so far on the local course), so that’s all that matters. Practically speaking, the difference for me between a 52 and 53, being a newb in TT has got to be negligible. I need to work on my power and pacing to get the greatest improvements. The 53 won’t really be any harder to race with, it’ll just give me a more stout small ring (and if I’m silly enough to sign up for a course that’s really steep, I’ll swap out the 11-25 for an 11-28 and should be all set).