Road Bike, Cycling Forums banner
1 - 9 of 9 Posts

·
Registered
Joined
·
317 Posts
Discussion Starter · #1 ·
First of all, I'm not a racer but a rec rider. But I like to go out and challenge myself and check my mph average as many of you do.

A couple of months ago I changed from a 52-39 chainring to a 50-34. Today I went out on a 30 mile ride with some hilly terrain and noticed my average speed was slower than when I used the 52-39 by 1/2 to 3/4 mph. I had to work hard to get that. I wonder if this could be due to the different chainrings.

It seems there is a lot more shifting/gear changing on the 50-34. It seems 50 -34 tooth combo makes it more difficult to find the right gear because of the large difference in gears. I am aware the 52 will give me a slight increase in speed on the flats over the 50 but wonder if the extra shifting causes loss of momentum/time. Maybe it's because I haven't gotten used to the 50-34 yet or maybe because I am a year older:)

Anyway, have any of you had similar results when changing from a 52-39 to a 50-34 or data that dispels my hunch?

Thanks in advance.
 

·
haole from the mainland
Joined
·
5,966 Posts
I ride a compact and found the 34 almost useless on the flats, plus I didn't like the big jump between chainrings. So I switched to a 36 and am happier.

I honestly don't think the compact is really responsible for you slowing down. It sounds like you got frustrated a bit and might have psyched yourself out.
 

·
Cannot bench own weight
Joined
·
4,298 Posts
Could be. I definitely think it was the reason I got "slower."

Reason why is that when the hills got tough, I'd just use my easiest gear and "spin" up. Which means slower then doing the same thing with 5 more teeth up front.
 

·
Spicy Dumpling
Joined
·
9,723 Posts
Einstruzende said:
Reason why is that when the hills got tough, I'd just use my easiest gear and "spin" up. Which means slower then doing the same thing with 5 more teeth up front.
There you go. I had the same experience when I went from riding my singlespeed on a local hilly loop with a lot of steep rollers. I was actually faster on the singlespeed because I'd jump on a bigger gear instead of spinning up. After adjusting to riding the geared bike again I've gone to bigger gears on the climbs when I can. I'm now much faster than before.
 

·
Banned
Joined
·
6,492 Posts
half a mile per hour on one ride is meaningless, IMO

Are you really so consistent that half or three-quarters of a mile per hour is outside your normal variability? I'm not--I've done the same commute for more than 25 years, and my speed varies by two or three miles per hour from one day to the next, or from morning to afternoon. I doubt I'd even be aware of 0.5mph.
That doesn't mean the gears aren't wrong for you, or for the terrain, but I don't think one bad ride demonstrates it. The "wrong gear" feeling may be a lack of familiarity. You could figure the ratios for the two cranksets and determine which gears you don't use and where you have gaps, then adjust accordingly. The forumula to get a result in "gear inches":
Divide the number of teeth in the cassette cog into the number in the chainring, then multiply by the diameter of the wheel in inches (for 700c rims, tradition says to use 27). Do that for both sets of chainrings., Or you could Google up a gear chart and save yourself the trouble. Either way, that will tell you what gears you had before that you're mssing now, if any, and show you comparable ratios with your new rings.
I mean, I wouldn't bother, but if I were going to bother, that's what I'd do.
 

·
Steaming piles of opinion
Joined
·
10,520 Posts
Nah. At least, not beyond a question of familiarity.

dasho said:
It seems there is a lot more shifting/gear changing on the 50-34. It seems 50 -34 tooth combo makes it more difficult to find the right gear because of the large difference in gears.
Not true in one sense, and minimally true in another. It's not true, in the sense that you only can't find a thing because you don't know where it is. Once you become accustomed to it, no issue. It's minimally true in the sense that you'll often need to execute an additional rear shift for every front shift to find the 'next' gear in your chart. That's only a fraction of a second, and only for relatively few shifts - it's not as if a bicycle is shifted sequentially all that often. Increased familiarity will help some, and training to increase your 'power band' (to borrow an automotive term) will cover the rest (and would be good no matter the gearing used.)



dasho said:
I am aware the 52 will give me a slight increase in speed on the flats over the 50
Only if you routinely ride above 35 mph on the flats and are spinning out your smallest cog. Otherwise, no difference there at all.

dasho said:
but wonder if the extra shifting causes loss of momentum/time.
Tiny amount, eliminated once you become accustomed to it.

dasho said:
Maybe it's because I haven't gotten used to the 50-34 yet or maybe because I am a year older:)
Little of each. Plus, you can't possibly draw a conclusion from one (or even three) rides. If you were so consistent that this amount was statistically significant, it was not because of 'real' factors, but because you were riding to the number on your computer. Real life (temperature, wind, tire inflation, hydration, nutrition, rest, recovery, training, clothing, and on and on) make far more difference than this 1/2 - 3/4 mph.

IMO, you're overthinking it. Ride, enjoy.
 

·
Banned forever.....or not
Joined
·
24,573 Posts
Nope, it must be that Aluminum foil helmet.

A gear is a gear is a gear.
A 53X19 will get you down the road the same speed as a 39X14 +/- a hair.
 

·
Cannot bench own weight
Joined
·
4,298 Posts
MR_GRUMPY said:
Nope, it must be that Aluminum foil helmet.

A gear is a gear is a gear.
A 53X19 will get you down the road the same speed as a 39X14 +/- a hair.
That's all well and good, but unless you are incredibly disciplined, you will find you end up using easier gears than you might have when you were on a 53/39. I was among the undisciplined, and I got slower because of it.

Cory is right to a point, if you're riding by yourself, does it make a difference? Not always, but some times you like to go out and try to set a PR of a familiar route. Where I really noticed was when I was riding with my club, and I started getting spit out the back on power climbs, when I used to be up near the front.
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top