Changing chainring to a “non-traditional” gearing 50/34 —> 50/42
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Changing chainring to a “non-traditional” gearing 50/34 —> 50/42
I recently got a new road bike after having ridden my previous bike for 13 years. My previous bike had a triple chainring, where the middle and larger chainrings were 42 and 52t. I literally *never* used the smallest chainring, as I would often drop the chain if for some reason I did end up shifting down.
Anyway, shiny new bike arrives and it’s a double chainring 50/34t. I find this gearing to be really terrible. The 34t chainring is too small to be useful to me, and so I find myself riding in the larger chainring almost exclusively. Gut instinct is that changing the small from 34t to 42t (to be more like my older bike) would be great - I feel like I’d get a lot more out of the bike overall.
What are the downsides to replacing the small chainring? Why should I NOT do this?
I don’t know enough about gear ratios to really understand the potential downsides, so I’d love any input/suggestions folks have. Fwiw the rear cassette on the new bike is 11-30t, the old bike was 12-25t.
Anyway, shiny new bike arrives and it’s a double chainring 50/34t. I find this gearing to be really terrible. The 34t chainring is too small to be useful to me, and so I find myself riding in the larger chainring almost exclusively. Gut instinct is that changing the small from 34t to 42t (to be more like my older bike) would be great - I feel like I’d get a lot more out of the bike overall.
What are the downsides to replacing the small chainring? Why should I NOT do this?
I don’t know enough about gear ratios to really understand the potential downsides, so I’d love any input/suggestions folks have. Fwiw the rear cassette on the new bike is 11-30t, the old bike was 12-25t.
Last edited by guapo337; 09-07-21 at 08:55 AM.
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More details about the components on your new bike are in order. There may not be any chainrings available for your crank in 42 teeth. Your previous triple did provide you with low gear options that you would lose completely by switching to a 42 tooth small ring. Perhaps you need to take some time to get used to your new setup. It all likelihood, depending on your actual crank, the largest small ring available may be a 36 or perhaps a 39 tooth small ring. However, because shift gates may no longer match properly, front shifting could be significantly degraded
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Why is this a problem? For people that live/ride in flatter areas, using the larger chainring most of the time is pretty normal and I sure as heck wouldn't actively seek out a "solution" to make front shifting more frequent than it needs to be. If anything, I'd probably go to a tighter cassette and leave the chainrings alone, since you don't need the 34/30 for climbing; go get another 12-25t (assuming 11 speed).
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I recently got a new road bike after having ridden my previous bike for 13 years. My previous bike had a triple chainring, where the middle and larger chainrings were 42 and 50t. I literally *never* used the smallest chainring, as I would often drop the chain if for some reason I did end up shifting down.
Anyway, shiny new bike arrives and it’s a double chainring 50/34t. I find this gearing to be really terrible. The 34t chainring is too small to be useful to me, and so I find myself riding in the larger chainring almost exclusively. Gut instinct is that changing the small from 34t to 42t (to be more like my older bike) would be great - I feel like I’d get a lot more out of the bike overall.
What are the downsides to replacing the small chainring? Why should I NOT do this?
I don’t know enough about gear ratios to really understand the potential downsides, so I’d love any input/suggestions folks have. Fwiw the rear cassette on the new bike is 11-30t, the old bike was 12-25t.
Anyway, shiny new bike arrives and it’s a double chainring 50/34t. I find this gearing to be really terrible. The 34t chainring is too small to be useful to me, and so I find myself riding in the larger chainring almost exclusively. Gut instinct is that changing the small from 34t to 42t (to be more like my older bike) would be great - I feel like I’d get a lot more out of the bike overall.
What are the downsides to replacing the small chainring? Why should I NOT do this?
I don’t know enough about gear ratios to really understand the potential downsides, so I’d love any input/suggestions folks have. Fwiw the rear cassette on the new bike is 11-30t, the old bike was 12-25t.
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Why is this a problem? For people that live/ride in flatter areas, using the larger chainring most of the time is pretty normal and I sure as heck wouldn't actively seek out a "solution" to make front shifting more frequent than it needs to be. If anything, I'd probably go to a tighter cassette and leave the chainrings alone, since you don't need the 34/30 for climbing; go get another 12-25t (assuming 11 speed).
Re: tighter cassette - can you explain how this would be helpful? If I'm understanding correctly, moving from 11-30t to 12-25t would make my "easiest" gear harder and thereby make using the smaller chainring slightly higher effort. Is that an accurate understanding?
What about switching to 53/39 on the front? What are the merits and downsides to doing that?
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More details about the components on your new bike are in order. There may not be any chainrings available for your crank in 42 teeth. Your previous triple did provide you with low gear options that you would lose completely by switching to a 42 tooth small ring. Perhaps you need to take some time to get used to your new setup. It all likelihood, depending on your actual crank, the largest small ring available may be a 36 or perhaps a 39 tooth small ring. However, because shift gates may no longer match properly, front shifting could be significantly degraded
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there’s no downside if the gearing works for you. Years ago I realized that a standard 53/39 crankset was “overgeared” for me, so I swapped out the 53 for 50, which was ideal at the time. I’ve since tweaked it up to a 51 which in combination with a 12/23 cassette, gives me a gear range ideal for me and my typical pace/terrain. The 39 loses me some low-end gearing compared to a compact crankset, but there’s nothing around here that can’t be climbed with a 39/23. That may change as I age. Switching to a 42 will restrict your climbing ability, but if your terrain isn’t extreme (and it sounds like a 42/25 low gear has been adequate in the past), go for it.
Thanks, very helpful. For what it's worth, I was riding the 42t bike throughout San Francisco and in Marin County, where I was regularly climbing 2-3k ft each ride. I recently moved to Boston where I've struggled to find 1k of vert over the same distance in my limited exploration. I think 42/30 would be more than enough, and based on past experience the 42/25 gearing would be fine as well.
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Shift up two gears on the rear derailleur at the same time. Problem solved.
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53/39T might require more thought about chain length, front & rear Der capability, chain stay clearance interference, & cassette cog selection/options.
I was disappointed a while back when a larger double wouldn't clear the frame. Everything else was good, but not the frame...
I was disappointed a while back when a larger double wouldn't clear the frame. Everything else was good, but not the frame...
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When I got my first compact crankset (50-34) I didn't like it so much but I adjusted to it and have put about 40K miles on it. Unlike you, I need the low gears for climbing but on less hilly rides I did find the 16 tooth gap annoying.
Give it some time and see if you get used to it. If not, you can probably get a 36 inner ring. Or, just stay in the big ring. I can stay in the 50 on some rides.
Give it some time and see if you get used to it. If not, you can probably get a 36 inner ring. Or, just stay in the big ring. I can stay in the 50 on some rides.
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This is a useful comment. Shifting with a compact that has a 16 tooth difference between chainrings is quite different from an older triple that has only an 8 tooth difference between the big and middle rings. Even a traditional 53-39 setup has a 14 tooth difference and usually requires a rear change along with a front shift to avoid that abrupt change in cadence you have been experiencing. With the 13-26 cassette I have on my bike I have to do a double or even triple rear shift when I drop from large to small ring with my 52-36 semi compact double crank. I have a 12-29 cassette on my other bike with a 50-34 compact and I have to do a double rear shift when going from large to small ring. Basically, you have to learn to do 2 things at once. With a bit of practice it becomes second nature.
Last edited by alcjphil; 09-07-21 at 08:50 AM.
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I share your dislike for 50 -34. I started my (derailleur bike) life on a 52-35 X 14-28, Way, wa better than enything I ever knew before but when I bought a triple with 52-42-30 (which I quicly changed to a 28), it was "Wow! This is it. I raced that bike, simply not using hte inner ring. Bought a real race bike. 1977. It was geared the usual 42-53 and I acquired 43,44,53 and 54, stitching them depending on the race. I was in my mid-20s, racing strong and loved to climb out of the saddle in big gears. I also loved the 52-42 shift with close ratios in back.
In the 40 years since, I've aged. The triple is a given on all my bikes. All my gearing has come down. But the concept I love hasn't. My best bike is set up 50-38-24; very close to a simply scaled down 53-42-28.
Years ago I had a race bike (but decades after my last race), I geared it 53-39, the gearing that existed but was not at all common when I was racing. Hated it. The 39 was too low to be a good flat ground gear and the shift up and down too big. Went back to the 52-42-28 and all was right again.
In the 40 years since, I've aged. The triple is a given on all my bikes. All my gearing has come down. But the concept I love hasn't. My best bike is set up 50-38-24; very close to a simply scaled down 53-42-28.
Years ago I had a race bike (but decades after my last race), I geared it 53-39, the gearing that existed but was not at all common when I was racing. Hated it. The 39 was too low to be a good flat ground gear and the shift up and down too big. Went back to the 52-42-28 and all was right again.
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You'd probably need to be a little more "patient" on upshifts since the ramps and pins on the 50T and 39T wouldn't be synchronized, but coming from older bikes, you know the drill.
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What I'm finding is that in the instances when I do drop into the 34, the change is pretty abrupt. I go from being in a gear that might be a little too hard to one that is far too easy (and I effectively just spin out). In my mind (uneducated on this topic, which is why I'm asking here), a larger chainring would make that shift down far less jarring. To be clear, I dont mean "jarring" and "abrupt" in that the shifting itself is unpleasant, I mean that the difference in effort/power required in each gear seems to change drastically moving from big to small.
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Boston and hills! Have you tried Blue Hill, just southeast of Boston in Milton. Or Chickatawbut Hill, also in Milton. Both are just small roads to a summit. Blue Hill climbs 400' in 9/10s of a mile. (I grew up 2 miles away and know it like the back of my hand. Chickatawbut used to be an anti-aircraft station and completely off-limits. I've only done it a couple of times. Much shorter, 280' as I recall and a far steeper average but the top section of Blue Hill is a bear. (I used to punish myself climbing it on a 42-14.)
In my (carless) racing days, I used to do day rides to Mt Wachusett (2000' summit and roughly 50 miles from Cambridge) and once did Pack Monadnock in New Hampshire (also a 2000' summit but short, steep and hard!).
In my (carless) racing days, I used to do day rides to Mt Wachusett (2000' summit and roughly 50 miles from Cambridge) and once did Pack Monadnock in New Hampshire (also a 2000' summit but short, steep and hard!).
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What I'm finding is that in the instances when I do drop into the 34, the change is pretty abrupt. I go from being in a gear that might be a little too hard to one that is far too easy (and I effectively just spin out). In my mind (uneducated on this topic, which is why I'm asking here), a larger chainring would make that shift down far less jarring. To be clear, I dont mean "jarring" and "abrupt" in that the shifting itself is unpleasant, I mean that the difference in effort/power required in each gear seems to change drastically moving from big to small. On 50/42, I did not have this same feeling.
Re: tighter cassette - can you explain how this would be helpful? If I'm understanding correctly, moving from 11-30t to 12-25t would make my "easiest" gear harder and thereby make using the smaller chainring slightly higher effort. Is that an accurate understanding?
What about switching to 53/39 on the front? What are the merits and downsides to doing that?
Re: tighter cassette - can you explain how this would be helpful? If I'm understanding correctly, moving from 11-30t to 12-25t would make my "easiest" gear harder and thereby make using the smaller chainring slightly higher effort. Is that an accurate understanding?
What about switching to 53/39 on the front? What are the merits and downsides to doing that?
Looking at your old gearing, I think that you have two problems:
- You're unaccustomed to the larger gap between chainrings. Others have already covered this - click up a couple of gears when you move to the small chainring
- You have much wider gearing than you need, making all shifts more abrupt than they need to be. On your previous setup, you state that you never went below the 40/25 gearing. Changing to a 12-25 on your current set-up would give you a low of 34/25 - that would a) remove some of the low end range that you don't need and instead b) give you less abrupt jumps between cassette shifts.
Moving to a 53/39 doesn't address either of these two problems and it's more expensive than changing out the cassette.
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Might be cheaper to swap cranks to an FSA Omega 46/30 or a Shimano GRX 11 spd. 46/30. Get you better low gearing. I ride my gravel which has 46/30 in the large ring all the time.
Just check that you can lower the front derailer a few mm.
Just check that you can lower the front derailer a few mm.
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You might want to read the OP's comments. What they don't like is the abrupt transition caused by the 16 tooth jump between their 50 and 34 tooth chainrings. This suggestion doesn't address that issue. Low enough gearing isn't the problem
Last edited by alcjphil; 09-07-21 at 09:52 AM.
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True, but there are few good options by actually changing rings. They might want to do a gear chart to visualize the changes. maybe a different cassette ?.
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That makes no sense whatsoever for the OP!
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OP, let us know how it goes.
........could just put an E-Assist in there. Let it take up the lack of gearing.
........could just put an E-Assist in there. Let it take up the lack of gearing.
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What I'm finding is that in the instances when I do drop into the 34, the change is pretty abrupt. I go from being in a gear that might be a little too hard to one that is far too easy (and I effectively just spin out). In my mind (uneducated on this topic, which is why I'm asking here), a larger chainring would make that shift down far less jarring. To be clear, I dont mean "jarring" and "abrupt" in that the shifting itself is unpleasant, I mean that the difference in effort/power required in each gear seems to change drastically moving from big to small. On 50/42, I did not have this same feeling.
Re: tighter cassette - can you explain how this would be helpful? If I'm understanding correctly, moving from 11-30t to 12-25t would make my "easiest" gear harder and thereby make using the smaller chainring slightly higher effort. Is that an accurate understanding?
What about switching to 53/39 on the front? What are the merits and downsides to doing that?
Re: tighter cassette - can you explain how this would be helpful? If I'm understanding correctly, moving from 11-30t to 12-25t would make my "easiest" gear harder and thereby make using the smaller chainring slightly higher effort. Is that an accurate understanding?
What about switching to 53/39 on the front? What are the merits and downsides to doing that?
If you have no difficulty turning the 50x11, you'll have no difficulty with 53x12.
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If your terrain or riding style don't need the range provided by a 50/34, then go with the 50/42. Your front shifting will be easier and less "disruptive". You'll lose some low-end gearing, but if you don't need it, who cares? If you can truly get by with a 42/25 low gear, switching from an 11-30 cassette to a 12-25 will further reduce range, but you'll be better able to get the optimal gear for most conditions you encounter. That's the route I took - my 10sp cassette is quite close ratio (straight 12-19, 21, 23), so a 12-tooth jump on the front requires a 2-3 sprocket shift in the rear, but it's easy to accomplish, and I can "fine-tune" my gearing to optimize cadence. If I know I'm going to be doing any serious climbing, I have a 13-29 cassette that I can swap on in a couple of minutes
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I should know better than to reply when the coffee has not kicked in. You are entirely correct. For some reason the word "triple" sat in my brain and I interpreted it as he never used the small as it never worked correctly and thus didn't like the 34 as that was what he wanted to fix.
Stupid me.
Stupid me.