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Why is the 53/39 ratio chainrings sacred?(23 posts)

Why is the 53/39 ratio chainrings sacred?sam-g
Mar 7, 2002 7:43 AM
I'm new to road biking, (coming from a running background of over 20 years) and have assembled a nice second hand road bike from a frame and parts purchased on this classified. Lately I've been attempting to dial in my correct fit by changing the stem, seat post and now crank size. My question is why the 53/39 ratio chainrings appear to be standard on virtually every double I've seen? In my brief riding experience of only about 500 miles, I rarely if ever use the 12 tooth small sproket but nearly always end up using the 25 on steep hills. By changing my chainrings to a 50/36 or 48/34, I could gain on the hills and lose almost nothing on the flats and downhills. The Ritchie Logic crankset I have has a 110 bolt spacing so that I can go as low as a 34 tooth small chainring. Any advice would be appreciated.
You'll get no argument from me. nmscottfree
Mar 7, 2002 8:01 AM
You've stumbled on the truth we try to hide...cory
Mar 7, 2002 8:03 AM
You may get a distorted picture from this board, because there are a lot of very serious and accomplished riders here. But I agree--53 teeth is overkill for nearly everybody. The road standard used to be 52-42, and even that was too high for efficiency in my mountainous area.
My main road bike now has a 46-36-26 triple and a 12-28 cassette, and I can ride anywhere comfortably. I don't remember ever needing a higher gear.
Having said that, though, if you're new to the sport, you'll probably get stronger, and if you decide to race, a 48 may be too short for you. But chainrings (and a cassette, if it comes to that) are cheap and easy to swap.
re: Why is the 53/39 ratio chainrings sacred?brider
Mar 7, 2002 8:12 AM
It's going to be based on a particular rider's ability (strength). Myself, I used to race a 54/42 up front and a 12-25 on back. Never had a problem. Now I'm using (and have been for some time) a 53/42 with an 11-23 in back. Seems to work for me.
re: Why is the 53/39 ratio chainrings sacred?Ray Sachs
Mar 7, 2002 8:15 AM
It's only sacred because racers use it. It shouldn't be sacred for 90% of us.

I have Ritchey 110 bcd double cranks on 3 bikes right now and run either 34-48 or 34-46 on them. A 48x12 high gear should be high enough unless you're trying to maximize speed on steep descents and even there you're probably better off coasting and getting as aerodynamic as possible. If it's not enough, you can always get a cassette with an 11 tooth cog. With a 46 or 48 tooth big ring, I guarentee you'll use your big ring a lot more than if you have a 53 on there.

-Ray
re: Why is the 53/39 ratio chainrings sacred?sam-g
Mar 7, 2002 8:55 AM
Ray,

Thanks for the advice, I'm inclined to go for a 48/34 set of chainrings. Since you have the same crankset, where would I find Ritchie chainrings? So far, all that I can find are Sugino alloy rings which I believe are very similar. Lickbike seems to have the best selection, but none appear to have ramps and pins found on the later model Shimano SG-X chainrings. Does it really matter? Also are there any other differences I should watch out for?

Sam
re: Why is the 53/39 ratio chainrings sacred?Ray Sachs
Mar 7, 2002 12:02 PM
I have various chainrings on mine. One might be an old Ritchey, a couple are Vueltas and a couple are Suginos. I've never had any problem with front shifting. To qualify that, I use a friction front shifter on two of my bikes, so that makes it easier. One of them has Dura Ace brifters though and it handles the front shifts fine. Maybe not as perfectly smooth as ramped and pinned DA rings, but just fine nonetheless. I have yet to lose time on a ride because of it.

-Ray
re: Why is the 53/39 ratio chainrings sacred?sam-g
Mar 7, 2002 1:05 PM
Ray,

On your Ritchie crankset which has a 34 small ring, do you have any clearance problems with the chainstays? Also what is the BB width? Is this size ring used with your DA index shifters or DA friction shifters? Thanks,

Sam
re: Why is the 53/39 ratio chainrings sacred?Ray Sachs
Mar 8, 2002 5:36 AM
No problems with clearing the stays - I have at least 5mm clearance. Those cranks work with a 107 bb on a road bike, maybe a 111-113 if you're using them on a bike with 135mm dropout spacing. I have this setup on three bikes, two of which are with friction front shifting, the third of which is with DA brifters, which are index (although with a double, it doesn't make much difference really) and DA front derailure. The derailure is designed for bigger rings but works fine with these smaller ones. It's a clamp on front derailure - braze on derailures can be a problem with smaller than standard front rings because you can't get the cage down low enough.

-Ray
re: Why is the 53/39 ratio chainrings sacred?Ping_Pong
Mar 7, 2002 8:20 AM
I would recomend swapping them out for something smaller if you are fairly new to the sport. Unless you ride a lot with fast groups a 53/12 is overkill. I ride 51/38 with a 13-23 on my training bike. This set up gives me some of the benefits you are looking for whilst keeping my gear ratios close together.
re: Why is the 53/39 ratio chainrings sacred?netso
Mar 7, 2002 8:31 AM
I had a 50/39 on my last bike. I liked it.
Probably because it creates a nice overlap...timfire
Mar 7, 2002 9:18 AM
Though I'm not sure, I would guess because it creates a nice overlap in gearing between the 39-14 and the 59-19. In those two gears you are pushing effectively identical gear inches (73.2 in the 39-14, and 73.3 in the 59-19).

If you are using a 12-23 cassestte, that would make your highest
i practical
(no small-small, big-big gearing) small CR gear (14) the same as your lowest big CR gear (19). This creates a smooth transition between the small and big CR's. If you were to switch your chainrings to some that were closer together, you would get more overlap, and thus would lose useful gears.

Understand what I'm trying to say? Hope that's not too confusing.

But on another note, I agree with others that the standard 53/39, 12-23 gearing is a little too high for the non-racer, myself especially. I've been thinking of switching to a lower gearing. Two thoughts I had was to either switch my casseste to a 13-27, or change the CR to a 49/36- a set-up that keeps nearly the same ratio between big and small CR (49-19 would give you 67.8 gear inches compared to 67.6 gear inches in 39-14). Of course you could also do both.

--TImothy Kleinert
Probably because it creates a nice overlap...curlybike
Mar 7, 2002 10:54 AM
Shimano has a 14-25 in their catalog, and a 13-26.
Probably because it creates a nice overlap...sam-g
Mar 7, 2002 11:53 AM
Tim,

I understand your point about the overlap, but don't see much of the value in that. Maybe I haven't riden enough to appreciate closer gear ratios. However I do see value to a wider range of gears, especially lower gears without having to go to a triple. Since I already have a fairly new DA 12/25 cassette, I figure that it would much cheaper to replace just the Ritchie/Sugino chainrings.

Sam
Lowest Common Denominatorgrzy
Mar 7, 2002 9:20 AM
Used to be a time that a 52/42 was sacred. Then people started looking at the available gear ratios with a critical eye and realized that there was a lot of redundancy. You could get almost the same gearing with the 42 and the 52 with certain rear cogs. With a little bit of math they realized that the 53/39 offered the least amout of redundancy and a fairly wide range that would work with various cog sets as the bike industry left behind old 5 and 6 speed freewheels and moved towards 7, 8, 9, and now 10 speed cogsets. Another angle is that if you're going to crank out bike parts with an eye on keeping the cost down you want some standardization - something that has always been hard to get in the bike biz. By settleling on one crank gearing the manufacturers (i.e. Shimano) can really get some economies of scale. They don't want to make every possible gearing combination under the sun. They want something that they can design their drive train around.

The other aspect is that the 53/39 gives people pretty good range. If you live in a place with some significant hills or mountains you will find that both the 53 and the 39 are quite useful - even when you run something like a 12-27 cogset. Now for the racer crowd they'll run something closer to a straight block, but will still want the 53 for the high speeds obtained in a pack (drafting) - lots of times they'll drop the 39 in favor of a 42 for closer gearing. Tri guys running 650 wheels will often run something larger than a 53 (Shimano makes a 55). A lot also depends on your cadence and fitness level. A RAAM rider might run a 57 up front, whereas someone new to cycling may find that the 53 doesn't get used all that much.

So the 39/53 is a compromise of sorts - it works for most people most of the time. If you find that you never use the 12 then get a cogset with the 13 being the smallest and go for the tightest range you can run. There is a good book out called "Bicycle Gearing" that goes over much of this, but you can work things out on your own if you make a matrix of your combos. Typically gear inches is used:

GI = front CR / rear cog x wheel diameter

So the 53/12 on a standard bike would be:

53/12 x 27" = 119.25 gear inches

With a little more math you can multiply by pi to get how far the bike moves with one crank revolution and you can then figure out what your speeds would be at various cadences. If you want to power up to 50 mph on a descent and maintain a reasonable cadence you'll soon realize that a 53/11 would be a nice thing to have.

Speed: 50 mph x 5280 ft/1 mi. x 1 h./ 60 min. = 4400 ft/min.

Gear Inches : 53/11 x 27" = 130.1 g.i.

One crank revolution: 130.1 gi x 3.1415 = 408.7 in./rev.

Cadence required for 50 mph: 4400 ft/min. x 12 in. / 1 ft. x 1 rpm/408.7 in./rev. = 129 rpm.

Now some will say that a cadence of 130 is nothing and that racers hit 160 or more, but you get the idea. Obviously a spread sheet works well for this.
re: WhyChen2
Mar 7, 2002 9:35 AM
You could lose some shifting performance. The curveture of the derailleur cage is shaped to fit the chain rings. You might consider less of a change in ring size (51-38)and then play with the cassette cogs to get the gearing you want. I've been converting my 12-25 and 12-27 cassettes to 13-25 and 13-27, and I'm going to try a 14-28 on my wife's bike (all 9-speed Shimano). So far I've left my rings at 53-39, changed the wife's triple from Ultegra to Campy 50-40-30 which fits her much better. I agree that most of us could use smaller chain rings. BTW, TA rings, a French company, seem to have a good reputation (for doubles) but I don't have a source for those anymore.
~Al
I thought that...PsyDoc
Mar 7, 2002 9:43 AM
...the reason most bikes are coming equipped with a 53/39 has to do with, in the case of Shimano, a BB that is not as wide as in the past. I used to run a 53/42 on my old Merlin Extralight and the BB was a 113 (I think). Now, the BB's on Shimano are 109.5, which brings the cranks a little bit closer together. Can you put a 42 tooth inner chainring coupled with a 109.5 BB and still have enough clearance between the chainstay and the inner chainring? I recall one poster mentioning that he used to run a 42, but that the clearance between that chainring and the chainstay was the width of a grain of sand.
re: Why is the 53/39 ratio chainrings sacred?LC
Mar 7, 2002 11:04 AM
Each road bike I have has a different set of chain rings (that is partly how I justify having so many bikes!) The cassette you match with the chainrings is every bit as important to match the type of riding you are trying to do.
Hilly race, flat race, recovery, touring.

53-39, 50-39, 46-36, 52-42-30.
And the cassettes:
12-27, 12-23, 11-28, 12-28
re: Why is the 53/39 ratio chainrings sacred?Barnyard
Mar 7, 2002 11:39 AM
In my opinion, and I know others who share the same opinion, 53 is too big! I find myself getting more use out of a 52.
re: Why is the 53/39 ratio chainrings sacred?SnowBlind
Mar 7, 2002 1:23 PM
Mainly road racing.
From what I see the half step system was more popular for non-racers and the cross system was prefered by racers back when 5 speed was the norm. That double shift every 2nd shift would have been a real bastard in a crit with downtube shifters!
Be interesting to see the current 9 or 10 speed set up half step, you would have as much range as a triple cross-chain setup. With the ease of double shifting, it would work well.
Looks like you could do 52-48, and run from 11-39 in 10% gear increments.

Personally, I rarely use my big ring before April or so.
The other, more expensive argumentDrPete
Mar 7, 2002 4:29 PM
...Sure, 53/39 is a bit much, and 50/36 would be nice, but 52/42/30 (i.e. Ultegra Triple) is the sweetest of all! I used to have an ego thing going with my 53/39 double until I rode the Civil War Century here in MD/PA. After 105 miles and 6500 feet of climbing, I realized that I was smoking on the descents but tiring myself out by mashing a slow cadence in the mountains. From that ride on I vowed to go triple, and I haven't looked back.

105 is a solid group and it offers a triple up front. I've learned that the triple gives you room to ride hard if you want, but you also have the option of taking it easy. Just my $0.02.
re: Why is the 53/39 ratio chainrings sacred?Steve Bailey
Mar 9, 2002 10:38 AM
You're not alone in finding that the 53/12 combo is too high a gear for average cyclists to utilize. Some feel that a 104 to 108 gear inch is just fine for the avg. folk, which translates into a 50/13 or so. You are also lucky in having in your possesion a Ritchey 110BCD double crank as it's a rare beast, and can now utlize a better selection of chainrings then are available in the 130BCD cranks.

Problem is the shifters. Typical Shimano STI (assuming Shimano here) has problems shifting up onto a large chainring (and a middle on a triple) when the rings aren't pinned and ramped to help the chain up onto the ring. STI is essentially an indexed front system with very little trim ability. This puts a burden on the rings to help move the chain. Or go the Campy route whose front shifters have many smaller index points and which can usually shift a chain up onto a basic chainring.

You may find that the typical 110BCD rings are not pinned and ramped, thus you may get poor shifting in the front. Your option is to hunt around for a large ring that's pinned/ramped - I'm unaware of any, others can help here.

Or, go to a different cassette, such as a Ultegra 9spd 14-25 for instance, maybe changing the larger cogs to larger then the stock 25, combining with a standard 130BCD crank with a 48/38 or so (note that a 38 is the smallest chairing available in 130BCD). You can get a TA 48 large ring in 130BCD that's ramped and pinned - pricy though at $45

SB
Source for chainringsgoathead1
Mar 11, 2002 11:39 AM
I recently went through the same dilemma for a touring / commuter bike I was building. I eventually settled on a Sugino 110 BCD double crank with 34/46 chainrings and a 12-25 9 speed cassette. I found an excellent array of chainrings at Cambria Bikes (www.cambriabike.com). I bought Real chainrings. They are ramped and work great with Tiagra STI shifters and an Ultegra front derailleur.