from rookie’s keyboard,
Hello, friends
I hope you’ve had a good weekend. Mine was fine. (I’d use a harsher word, but my anger management therapist a.k.a. me said I should be more positive.)
I used the time to replace the old and beaten 11-25 cassette on one of my steel retro road bikes (I own two) with a new 11-28 model.
The 11-25 was about 20 years old. Don’t worry. It was in good condition (teeth steel intact) when I bought the bike, but I saw a good deal for an 11-28 model and went for it.
Why?
I needed the lower gearing. My bike has classic 54/42 chainrings, and I found myself struggling with the 11-25 cassette on some of the more demanding hills in the city.
I also had to replace the chain as the old one didn’t operate well with the new cassette. As some of you may know, this is not uncommon. Chains stretch over time and become unusable (skipping, jumping…etc.) when combined with a new cassette and/or chainrings. (I kept the original chainrings as they work just fine with the new chain.)
The difference?
Well, the difference is only 3 teeth, but it’s undoubtedly perceivable. I was so surprised by the performance that decided to do some math.
When it comes to cassette analysis, it’s crucial to become familiar with a little concept known as gear ratio.
The gear ratio shows the number of full spins that the rear cog in use makes per one full revolution of the chainring. You find the gear ratio by dividing the number of teeth on the chainring by the number of teeth on the cog.
In my case, the gear ratios of my lowest gears with a 25T and a 28T rear cog compare as follows:
- 42T/25T=1.68
- 42T/28T=1.5
The lower the gear ratio, the easier it is to spin the cranks because each revolution requires the rear wheel to make fewer rotations. The less the rear wheel has to rotate, the easier it is to propel the bike forward.
In my case, the difference amounts to 11.32% (the decrease from 1.68 to 1.5). In other words, a 28T gives me an 11.32% lower gear.
The number isn’t insane, but it’s definitely noticeable on the terrain that I cover.
What is the cost?
As the wise among you probably know, you can’t get something for nothing in this world.
So, why did I sacrifice to acquire to acquire my lower gearing?
Only one thing – slightly sub-optimal cadence due to the larger jumps between the gears.
Some of you may not know what cadence is. After all, this site is called rookiejournal.com, not expertpro.com
Cadence is a term used to indicate the number of crank/chainring rotations that the rider makes in 1 minute. The abbreviation is RPM (rotations per minute).
A higher cadence is considered beneficial as it doesn’t fatigue the rider as much while allowing the maintenance of a consistent average speed. Smaller jumps between the gears make it easier to maintain a steady cadence. Large jumps…do the opposite.
When two cassettes have the same number of cogs, the cassette with the lower 1st gear (or larger large cog, in simple terms) comes with bigger gear transitions/gaps.
In my case, I have a 7-speed cassette (don’t laugh! It’s plenty for me.)
So, here are the gradations of my old and new cassette compared back to back:
- 11-13-15-17-19-22-25
- 11-13-15-18-21-24-28
| Jumps | 1 | 2 | 3 | 4 | 5 | 6 |
| 11-25 | 2T | 2T | 2T | 3T | 3T | |
| 11-28 | 2T | 2T | 3T | 3T | 3T | 4T |
The 11-28 cassette has three slightly larger jumps. But the difference is only 1 extra tooth and is quite frankly inconsequential, especially since I am using my bike for commuting.
But even if I was racing on it, 1 extra tooth wouldn’t be enough to hurt my cadence. For that to happen, the largest cog will have to be around 32T.
Honestly, I prefer the extra low range rather than the ever so slightly smaller jumps.
A Note On Joint Pain
The lower gearing doesn’t help only with climbing. It also reduces the stress on the joints. If you have inflamed knees due to too much riding in gears that are too high for your capabilities, a cassette with a lower gearing can be the remedy. (Of course, you first need to rest for a while, if the overuse injury is legit.)
I don’t have that issue…but wanted the lower gear to get more mileage per unit of effort exerted on an ascent.
I know that many of you aren’t riding road bikes from the previous millennium and probably have transmissions with more than 7 speeds at the back.
Hence I made the tables below comparing the gradation of 11-25 and 11-28, 10/11-speed cassettes.
10-speed 11-25 and 11-28 Cassette Comparison
| Shimano (11-25) | 11-12-13-14-15-17-19-21-23-25 |
| Shimano (11-28) | 11-12-13-14-15-17-19-21-24-28 |
| SRAM (11-25) | 11-12-13-14-15-17-19-21-23-25 |
| SRAM (11-28) | 11-12-13-14-15-17-19-22-25-28 |
| Campagnolo | 11-12-13-14-15-17-19-21-23-25 |
10-speed 11-25 and 11-28 Cassette Comparison
| Shimano (11-25) | 11-12-13-14-15-16-17-19-21-23-25 |
| Shimano (11-28) | 11-12-13-14-15-17-19-21-23-25-28 |
| SRAM (11-25) | 11-12-13-14-15-16-17-19-21-23-25 |
| SRAM (11-28) | 11-12-13-14-15-16-17-19-22-25-28 |
| Campagnolo | 11-12-13-14-15-16-17-19-21-23-25 |
Well, nothing surprising here, really.
10 and 11-speed cassettes offer minimal jumps between the gears as small as one extra tooth per cog. After all, that’s the main purpose of having extra gears/cogs.
The difference between the transitions is minimal again.
If I were you, I’d choose an 11-28 cassette. It’s just more functional. But if you are currently “torturing” an 11-25 cassette, ride it until it “burns”.
Never forget that optimal/perfect is the enemy of done/good.
Until next time,
– rookie
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