Changing chainring to a “non-traditional” gearing 50/34 —> 50/42
#51
Senior Member
Join Date: Jun 2013
Location: location location
Posts: 3,035
Bikes: MBK Super Mirage 1991, CAAD10, Yuba Mundo Lux, and a Cannondale Criterium Single Speed
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 344 Post(s)
Liked 297 Times
in
207 Posts
The downside of the tighter cassette is that you have to make more rear shifts when changing chainrings. With my 13-26 cassette which has the same gaps as a 12 -25 cassette I have to make 3 rear shifts when changing chainrings. With the 12-29 on my other bike, I only make 2. Your 11-30 would be similar
3 shifts is 1 throw of the downshift lever on shimano or Campag shifters (if going to the big ring) or 3 quick clicks of the thumb/upshift lever (if going small ring) and if you’re at a point of front-shifting, you’re rarely going to be making those full 3 rear shifts; most big ring shifts happen as you’re a) reaching the part of the climb where it starts to get really steep and you go to the small ring or b) going over the top of the climb starting the descent.
You make 3 shifts at the rear to stay in the same gear as before the front shift. But almost by definition, you’ll only front-shift at a point where you’re making a big shift in gear anyway. Even with a 12-25 cassette.
Likes For Leinster:
#52
Method to My Madness
Join Date: Nov 2020
Location: Orange County, California
Posts: 3,641
Bikes: Trek FX 2, Cannondale Synapse, Cannondale CAAD4, Santa Cruz Stigmata GRX
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1939 Post(s)
Liked 1,463 Times
in
1,012 Posts
(a) 50:19 = 2.63, next lower gear combination on 34T chain ring is 34:14 = 2.43, from 19T to 14T is 5 upshifts (given that 34:13 = 2.62, which is almost the same rather than the next lower gear combo);
(b) 50:21 = 2.38, next lower gear combination on 34T chain ring is 34:15 = 2.27, from 21T to 15T is 5 upshifts;
(c) 50:23 = 2.17, next lower gear combination on 34T chain ring is 34:17 = 2.00, from 23T to 17T is 4 upshifts (given that 34:16 = 2.13, which is almost the same rather than the next lower gear combo);
(d) 50:25 = 2.00, next lower gear combination on 34T chain ring is 34:18 = 1.89, from 25T to 18T is 4 upshifts.
But in practice, because one also loses momentum shifting between the chain rings, shifting 3 rear cogs feels about right.
Last edited by SoSmellyAir; 09-10-21 at 04:08 PM.
#53
Senior Member
Join Date: Jun 2013
Location: location location
Posts: 3,035
Bikes: MBK Super Mirage 1991, CAAD10, Yuba Mundo Lux, and a Cannondale Criterium Single Speed
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 344 Post(s)
Liked 297 Times
in
207 Posts
With a 12-25 cassette, you need to shift more than 3 rear cogs after shifting between the front 50/34 chain rings to mathematically minimize disruption to cadence.
Most other gear shifts can be dealt with in the rear, unless you’re already all-the-way cross-chained.
Likes For Leinster:
#54
Method to My Madness
Join Date: Nov 2020
Location: Orange County, California
Posts: 3,641
Bikes: Trek FX 2, Cannondale Synapse, Cannondale CAAD4, Santa Cruz Stigmata GRX
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1939 Post(s)
Liked 1,463 Times
in
1,012 Posts
But my point is that if you’re front-shifting, you’re not trying to minimize disruption to cadence; you front shift when you need to make a significant change to your cadence and/or when meeting a significant change in terrain that will require a change in cadence. You front-shift when you’re in 50-23 and you can see the road getting steeper. You front-shift when you’re going over the top of a climb and starting a descent. You front-shift as you exit the gravel sector onto the smooth asphalt.
#55
Senior Member
Join Date: Oct 2015
Posts: 15,481
Bikes: 2015 Workswell 066, 2017 Workswell 093, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE
Mentioned: 144 Post(s)
Tagged: 0 Thread(s)
Quoted: 7648 Post(s)
Liked 3,465 Times
in
1,831 Posts
But my point is that if you’re front-shifting, you’re not trying to minimize disruption to cadence; you front shift when you need to make a significant change to your cadence and/or when meeting a significant change in terrain that will require a change in cadence. etc .
I often shift down in front and way up in back at the base of a long climb because it is easier Not to shift up front under heavy load, even with modern equipment. I can look up the road (assuming it is straight enough) or if I know the route, I can prepare for the upcoming terrain. I Rarely want big changes in cadence because I have a pretty limited range of optimal output, and I don't want to go a lot slower, and faster is only good at certain points on climbs.
There are a couple places I can think of where I come downhill into a turn uphill where I need to drop from 50-midrange of 34 midrange (or just work down the cassette if I am not too tired) but as a rule I try to plan so I don't have to make big gearing jumps unless the terrain also makes big jumps ... short, steep rollers for instance. And to me the whole point of having all those ratios is that I can always find a ratio which keeps me in my peak output range---peak balance of power and revs so that my lungs and heart and legs can all keep contributing. I might spin a little faster on some hills because I feel like quicker strokes are more efficient (less power momentum lost between power pulses) but i never want to go from say, 85 revs to 65 revs on a climb. Or anywhere else, really,.
#56
Method to My Madness
Join Date: Nov 2020
Location: Orange County, California
Posts: 3,641
Bikes: Trek FX 2, Cannondale Synapse, Cannondale CAAD4, Santa Cruz Stigmata GRX
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1939 Post(s)
Liked 1,463 Times
in
1,012 Posts
Hmmm ... maybe I am doing it wrong.
I often shift down in front and way up in back at the base of a long climb because it is easier Not to shift up front under heavy load, even with modern equipment. I can look up the road (assuming it is straight enough) or if I know the route, I can prepare for the upcoming terrain. I Rarely want big changes in cadence because I have a pretty limited range of optimal output, and I don't want to go a lot slower, and faster is only good at certain points on climbs.
There are a couple places I can think of where I come downhill into a turn uphill where I need to drop from 50-midrange of 34 midrange (or just work down the cassette if I am not too tired) but as a rule I try to plan so I don't have to make big gearing jumps unless the terrain also makes big jumps ... short, steep rollers for instance. And to me the whole point of having all those ratios is that I can always find a ratio which keeps me in my peak output range---peak balance of power and revs so that my lungs and heart and legs can all keep contributing. I might spin a little faster on some hills because I feel like quicker strokes are more efficient (less power momentum lost between power pulses) but i never want to go from say, 85 revs to 65 revs on a climb. Or anywhere else, really,.
I often shift down in front and way up in back at the base of a long climb because it is easier Not to shift up front under heavy load, even with modern equipment. I can look up the road (assuming it is straight enough) or if I know the route, I can prepare for the upcoming terrain. I Rarely want big changes in cadence because I have a pretty limited range of optimal output, and I don't want to go a lot slower, and faster is only good at certain points on climbs.
There are a couple places I can think of where I come downhill into a turn uphill where I need to drop from 50-midrange of 34 midrange (or just work down the cassette if I am not too tired) but as a rule I try to plan so I don't have to make big gearing jumps unless the terrain also makes big jumps ... short, steep rollers for instance. And to me the whole point of having all those ratios is that I can always find a ratio which keeps me in my peak output range---peak balance of power and revs so that my lungs and heart and legs can all keep contributing. I might spin a little faster on some hills because I feel like quicker strokes are more efficient (less power momentum lost between power pulses) but i never want to go from say, 85 revs to 65 revs on a climb. Or anywhere else, really,.
Likes For SoSmellyAir:
#57
cycles per second
Join Date: Oct 2003
Location: Minnesota
Posts: 1,930
Bikes: Early 1980's Ishiwata 022 steel sport/touring, 1986 Vitus 979, 1988 DiamondBack Apex, 1997 Softride PowerWing 700, 2001 Trek OCLV 110
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 44 Post(s)
Liked 71 Times
in
48 Posts
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.
#58
Senior Member
Join Date: Nov 2018
Location: Redmond, WA & Bangkok, Thailand
Posts: 565
Bikes: 1999 Giant ATX MTB, 2002 Lemond Zurich, 2018 Fuji Transonic 2.3, 2019 Specialized Tarmac Disc Expert
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 170 Post(s)
Liked 391 Times
in
226 Posts
My three road bikes all have different gearing although two are very close. The Fuji has a 52/36 up front with a 11-28 cassette in the rear. My Specialized came stock with a 52/36 and an 11-30. After two years I replaced the rear cassette and put on an 11-32. This is an even better set up on hills. My LeMond is a triple with 52/42/30. The original cassette was a 12-25 9spd. Now it has a 12-28. If I ever were to use the 30-28 (as low as it goes) I'm probably on some hill I shouldn't be on in the first place!