Chainring sizing question... 50/39?
#1
Chainring sizing question... 50/39?
Currently riding with a triple that has 52/42/30 tooth rings and I NEVER use the 30 and only use the 52 when I've got a tailwind or a downhill, or I'm really hammering. (My rear cassette is a 12-25 10-speed) Otherwise, I ride almost entirely in the 42.
I'm going to upgrade my crank and will probably switch to a double, since I ride flat roads in Illinois and really have no use for a triple.
Having a hard time deciding if 53/39 or 50/34 makes sense. The 50 tooth seems right, but 34 tooth seems way too low. Is there such a thing as a 50/39 or a 50/42? Would this result in just a bunch of overlap in gears?
I mostly want to avoid having to constantly switch between big/little up front when riding, and I'm afraid the 34 will be way too low, and the 50 will be too high. Thoughts?
I'm going to upgrade my crank and will probably switch to a double, since I ride flat roads in Illinois and really have no use for a triple.
Having a hard time deciding if 53/39 or 50/34 makes sense. The 50 tooth seems right, but 34 tooth seems way too low. Is there such a thing as a 50/39 or a 50/42? Would this result in just a bunch of overlap in gears?
I mostly want to avoid having to constantly switch between big/little up front when riding, and I'm afraid the 34 will be way too low, and the 50 will be too high. Thoughts?
#2
Senior Member
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From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
50/39 exists.
50/42 can be done by switching the 39T for a 42T from your triple.
check out https://www.chainreactioncycles.com/ they have a sale going on for cranksets in the gearing you want.
50/42 can be done by switching the 39T for a 42T from your triple.
check out https://www.chainreactioncycles.com/ they have a sale going on for cranksets in the gearing you want.
__________________
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
#3
I used to use a 50 tooth big ring on my road bike with a 39 tooth small ring. I liked the smaller gap in size between the two rings. There are various companies that make 50 tooth rings to fit 130mm bcd cranks, the one I used was made by FSA. You could also buy a compact crank and buy a 38 or 39 tooth ring to replace your inner ring and keep the smaller ring in case you ever need to do some hills
#4
50/39 exists.
50/42 can be done by switching the 39T for a 42T from your triple.
check out https://www.chainreactioncycles.com/ they have a sale going on for cranksets in the gearing you want.
50/42 can be done by switching the 39T for a 42T from your triple.
check out https://www.chainreactioncycles.com/ they have a sale going on for cranksets in the gearing you want.
Just picked me up a 105 50/39 for $32!!!
#6
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Joined: Dec 2008
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From: Orange Park, Florida
Bikes: jamis xenith comp '08, trek 750 hybrid (w/drops) c.1995, centurian fixie, kona cindercone mtb c.2000
The 50/34 compact crankset has been used on many recreational road bicycles to create a lower and wider range of gearing for the average club type cyclist.
I live in Florida, which is mostly flat, and my Jamis Xenith Comp came with a FSA compact crankset of 50/34. After accidentally dropping into the 34 a few times I swapped out the 34 for a 40 (one tooth larger than the more common 39). I later changed the 50 to a 52, but I'm kinda limited from going any bigger due to the 110 bcd of the crankset.
My suggestion would be to check the sheldonbrown.com gear calculator and play with the range of gears that can be created by swapping out chainrings. Then visit your LBS to find your solution
I live in Florida, which is mostly flat, and my Jamis Xenith Comp came with a FSA compact crankset of 50/34. After accidentally dropping into the 34 a few times I swapped out the 34 for a 40 (one tooth larger than the more common 39). I later changed the 50 to a 52, but I'm kinda limited from going any bigger due to the 110 bcd of the crankset.
My suggestion would be to check the sheldonbrown.com gear calculator and play with the range of gears that can be created by swapping out chainrings. Then visit your LBS to find your solution
#7
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From: Perth, W.A.
If you change out an inner ring from what came with the crank it pays to stick with 10-speed specific ones. There are lots of other brand 9/10 speed rings available but the shifting is not always as good as it could be.
#10
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From: Orange Park, Florida
Bikes: jamis xenith comp '08, trek 750 hybrid (w/drops) c.1995, centurian fixie, kona cindercone mtb c.2000
I do realize that, however, matching rings for the FSA crankset that I have stopped at 52. And, fwiw, I am kinda silly about aesthetics.

If the bike is only for commuting, then I'd agree. I like to ride fast and long and often found myself spun out while trying to hang onto the group. When I started to do a few races I found the extra effort from being spun up killed my chances of contention. My first race this season I was out the back in the first few miles (not a 10th of the way in) when I couldn't accellerate enough down a short-steep hill because I didn't have enough gear.
So, not much difference for commuting, but every little bit helps when racing.

So, not much difference for commuting, but every little bit helps when racing.
#11
ah.... sure.
Joined: Mar 2008
Posts: 4,107
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From: Whidbey Island WA
Bikes: Specialized.... schwinn..... enough to fill my needs..
I do realize that, however, matching rings for the FSA crankset that I have stopped at 52. And, fwiw, I am kinda silly about aesthetics.

If the bike is only for commuting, then I'd agree. I like to ride fast and long and often found myself spun out while trying to hang onto the group. When I started to do a few races I found the extra effort from being spun up killed my chances of contention. My first race this season I was out the back in the first few miles (not a 10th of the way in) when I couldn't accellerate enough down a short-steep hill because I didn't have enough gear.
So, not much difference for commuting, but every little bit helps when racing.

If the bike is only for commuting, then I'd agree. I like to ride fast and long and often found myself spun out while trying to hang onto the group. When I started to do a few races I found the extra effort from being spun up killed my chances of contention. My first race this season I was out the back in the first few miles (not a 10th of the way in) when I couldn't accellerate enough down a short-steep hill because I didn't have enough gear.
So, not much difference for commuting, but every little bit helps when racing.
#14
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From: Orange Park, Florida
Bikes: jamis xenith comp '08, trek 750 hybrid (w/drops) c.1995, centurian fixie, kona cindercone mtb c.2000
oh, ow, stop stop....
This was an older picture, sorry I didn't state that when posting my pic. That was pre-final set-up, I couldn't find a more recent picture showing the crankset.
The point being that I like the black ring with the silver cutaways. Of course, now that I've been called out I had to double check and my newer FSA ring is all black with silver teeth.

oh well. And before you get started, the seat angle is more of an optical illusion.
This was an older picture, sorry I didn't state that when posting my pic. That was pre-final set-up, I couldn't find a more recent picture showing the crankset.
The point being that I like the black ring with the silver cutaways. Of course, now that I've been called out I had to double check and my newer FSA ring is all black with silver teeth.

oh well. And before you get started, the seat angle is more of an optical illusion.
Last edited by droobieinop; 05-03-10 at 10:45 AM.
#16
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From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
The real deals are the 10sp 105 cranksets. $117~$130 for most double, compact or triple, black or silver.
__________________
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
#17
Would there be an advantage to paying 4 times as much for a 10 speed model vs. a 9 speed model?
#18
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https://www.jensonusa.com/store/produ...kset+W+Bb.aspx
#19
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From: Longmont, CO
Bikes: Litespeed Tuscany, Giant OCR Tourting, Co-Motion Tandem
Back a few years, most road bikes came with 53/42. Then 53/39 came along and I think it was mainly for those riding more mountainous areas. I have been riding a triple and, like you, find I often ride all day in the 42 ring if on flatter terrain (love my 28 small ring for really big climbs). My friends with compact doubles are finding (when riding on flatter terrain) they are often switching between rings and the ends of the cassette (big - lttle cogs) trying to find the right gear. I suggest you stay with the 42 and pair it with a 52 or 53 for those tailwind/downhill situations. I don't think 50/34 makes sense for your riding.
#20
pan y agua

Joined: Aug 2005
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From: Jacksonville
Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike
What's wrong with the current crank? If you don't like having a triple, you can always take the inner chainring off, adjust the front derailleur, and you have a double.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
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You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
#21
How about fc-r700(ulegraish compact) cranks w/ BB for $95? Sounds like a better deal..
https://www.jensonusa.com/store/produ...kset+W+Bb.aspx
https://www.jensonusa.com/store/produ...kset+W+Bb.aspx
Back a few years, most road bikes came with 53/42. Then 53/39 came along and I think it was mainly for those riding more mountainous areas. I have been riding a triple and, like you, find I often ride all day in the 42 ring if on flatter terrain (love my 28 small ring for really big climbs). My friends with compact doubles are finding (when riding on flatter terrain) they are often switching between rings and the ends of the cassette (big - lttle cogs) trying to find the right gear. I suggest you stay with the 42 and pair it with a 52 or 53 for those tailwind/downhill situations. I don't think 50/34 makes sense for your riding.
I think you're right about the 34t being too low to be useable in most riding, and I don't think I need a 53t (or even a 52t) big since I'm rarely on the small half of my cassette while riding in my 52t now. A 53/39 might work, but the jump between the small and big seems unnecessarily big when I don't need the extreme ends of either gear and sounds like I'd just be cross-chaining a lot.
Taking the small ring off doesn't accomplish anything other than removing a tiny amount of weight and getting rid of 10 gears. It also seems like the centerline of my drivetrain would be pushed to the outside too much with this setup, whereas a double keeps things more centered on the rear cassette. The cross chaining on a triple 10-speed is pretty crazy if you're trying to ride 52-25 or 30-12, for instance... but on a double it's probably more reasonable to ride the bigger cogs while in the big chainring, right?
#22
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Joined: Jun 2007
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From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
How about fc-r700(ulegraish compact) cranks w/ BB for $95? Sounds like a better deal..
https://www.jensonusa.com/store/produ...kset+W+Bb.aspx
https://www.jensonusa.com/store/produ...kset+W+Bb.aspx
and they don't come in black, standard double or triple options.
or any other size than 172.5mm
so if you don't want a 172.5mm compact crank, then the CRC offer is better.
__________________
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
#23
pan y agua

Joined: Aug 2005
Posts: 31,812
Likes: 1,234
From: Jacksonville
Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike
In your own post, you said that the 42 tooth middle ring covers most of your riding. There's little reason, other than vanity, to change. And if you're riding in the middle chainring the vast majority of the time, cross chaining is not an issue.
But it's your money.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
#24
Fixed.
In your own post, you said that the 42 tooth middle ring covers most of your riding. There's little reason, other than vanity, to change. And if you're riding in the middle chainring the vast majority of the time, cross chaining is not an issue.
But it's your money.
In your own post, you said that the 42 tooth middle ring covers most of your riding. There's little reason, other than vanity, to change. And if you're riding in the middle chainring the vast majority of the time, cross chaining is not an issue.
But it's your money.
#25
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FC-R700 comes in 165, 170, 172.5 and 175mm lengths, Jenson just has the 172.5.
It also weights only twenty grams more than a standard ultegra crank, which isn't a big deal at all.
So, I don't know what that your reasoning for that was, but if you want a compact, the r700 crank is a much better deal.
Last edited by clink83; 05-04-10 at 10:04 PM.




