Understanding gearing and drive train.

[diegogarcia]

Got myself royally confused with my set up, which is due to a bit of illness, which is in turn affecting me on the bike.

I ride one bike 110bcd 52/36 with a 12/27 on the bike which is great (climbing bike).

I ride another bike 130bcd 53/39 with 12/25 on the bike which is great (fast and flat bike).

However, I seem to be tiring quicker on the bike with 53/39 than I do on the bike with 52/36. Common sense tells me to bail the 53 ring, buy a 52 but I cant believe one tooth on an oval chainset can make that much difference, which is why I think it is a combo of both front and back?

However, I could even look at going back to 110bcd on the second bike and running 50/34 - 12/25 but in my head I think I will not attain as much speed on the bike on the flat. Does this make any sense? Cost is the real issue of course and would like to solve this as 'cheaply' as I can. On the 52/39 bike it is as if at 1 hour 30 mins or so, the plug gets pulled. I emailed Rotor who said that at the big point, 52 is akin to 58 round and if I had a 58 round on my bike that would be crazy, so could this be the issue?

I have had fitted up on both bikes and excellent position. Pelvis rotates well due to 170 cranks, nice position over pedal, nice flat back, no shoulder roll off and nice ben elbows and good view.

Any further advice appreciated.

Diego.

[artray]

"However, I seem to be tiring quicker on the bike with 53/39 than I do on the bike with 52/36. Common sense tells me to bail the 53 ring"

Problem solved

[diegogarcia]

"However, I seem to be tiring quicker on the bike with 53/39 than I do on the bike with 52/36. Common sense tells me to bail the 53 ring"

Problem solved

Is it as simple as that then, despite the smaller cassette ?

[mrfish]

Gearing wouldn't make much difference to anything, assuming you ride the same rpms and the bike is the same. I would expect that you end up riding the bikes differently - maybe hanging onto 53x25 up hills whereas you'd be on 52x27, which might be enough to make a difference? Similarly at the low end of the cassette. Or it might be that you sit in the saddle for longer on the flat bike. Maybe try using a Garmin or similar to measure rpm for a typical ride and then run a comparison to try to eliminate that as a variable?

The other obvious cost saving measure is to get rid of the oval rings as they don't give 'free power' and round ones change better...

[artray]

Stay with the same set up on your chainrings. Just go for a wider ratio on your cassette, unless your going up Mt Zoncolan. There should be enough to get you up most climbs. No shame in going compact if need be, Sastre rode the tour with a compact. If your riding 2 bikes then keep them as similar as you can. If your bikes are very different in size set up then you will always have problems adjusting. The pro riders change bikes ,they usually have a identical 2nd bike.

[diegogarcia]

Gearing wouldn't make much difference to anything, assuming you ride the same rpms and the bike is the same. I would expect that you end up riding the bikes differently - maybe hanging onto 53x25 up hills whereas you'd be on 52x27, which might be enough to make a difference? Similarly at the low end of the cassette. Or it might be that you sit in the saddle for longer on the flat bike. Maybe try using a Garmin or similar to measure rpm for a typical ride and then run a comparison to try to eliminate that as a variable?

The other obvious cost saving measure is to get rid of the oval rings as they don't give 'free power' and round ones change better...

Cheers, cant say my Rotors shift badly at all. Certainly had no issues and never miss a beat nor drop a chain.

Appreciate the reply however. One thing though. Rotor say that the load of an oval chain ring increases and drops. Sounds stupid, but is a round ring the same all the way round then ? 53 is 53 type thing ? I think I will drop back to 52 oval for now, or perhaps even try round again....as the one thing that puzzles me is that Rotor bleat on about how great oval is then the release round rings and a lot of riders migrated back to round....?!?!?!?

[diegogarcia]

Stay with the same set up on your chainrings. Just go for a wider ratio on your cassette, unless your going up Mt Zoncolan. There should be enough to get you up most climbs. No shame in going compact if need be, Sastre rode the tour with a compact. If your riding 2 bikes then keep them as similar as you can. If your bikes are very different in size set up then you will always have problems adjusting. The pro riders change bikes ,they usually have a identical 2nd bike.

Thanks. Will give it some thought. Has never been an issue and can get about on either or, but of late, I feel that by moving to 53 I fatigue quicker. Could be something else as I have the power but fades quickly. It may simply be this early into the season and will soon click. Thanks again.

[mjduct]

http://www.bikecalc.com/gear_ratios

here you go I did it for you:



find the similar ration for both bikes and go pound some pavement in them and see if there is truly something different about your 2 setups. if a 2.5 ratio feels better or worse on one bike, maybe you need to tune up a derailler or a hub or something...

or it could be the final word on Aero vs. not!!!!!

[inakidman]

Thanks for the nice link. I hope im not off topic with my q.

50-25= 2.0
53-27= 2.0

A.) Does this mean that I will be exerting the same effort when climbing (the same slope using the same bike but with different gearing setup ) when im using 50-25 and 53-27? Will I be exerting the same strength? Will my cadence change? Is this even neccessary?
B.) If I want the best of both worlds with one bike, can I setup
my gears as 53/34 with 11-27?

Newbie here.

[mvogt46]

No a 50/25 and a 53/27 gear ratio are not the same. For a more accurate view you should look at the gear inches and not the gear ratio of that gearing setup.

For example 50/25 = 52.6 inches where 53/27 = 51.6 inches, therefore the 53/27 gear setup is a smaller gear to ride. In basic terms, gear inches are the distance covered by each turn of the pedals. It is also known as the gain ratio. So if you were to ride both gear setups at the same cadence the 50/25 setup would see you obtain a faster speed.

Gear inches are the basic unit of measurement most track riders use when deciding on what gear to run.

[fordred]

bigger chain rings don't make u tire faster. to put it simply, it's the resistance + cadence u are using. With a bigger chainring, just use a bigger cog at the rear to achieve the same or similar resistance + cadence.

[inakidman]

This post has been very helpful. Helps me be coinscoius with gearing when I ride and what I can do to adjust. Experience will tell me eventually what gears to use depending on my goals ang route.

I sometimes feel that I cant decide between gears and often settle with a faster cadence, or slower speed than I could have wanted. I don't want to prematurely get tired by using too heavy gears.

I'm sure this is a common newbie challenge.

Should we even mind this?

[stella-azzurra]

To All,

Please use this gear calculator it is very intuitive to use.

http://www.gear-calculator.com/#

It will answer many questions for you about gearing, speed and RPM.

The thing it can't help you with is the kinda of shape you need to be in to turn a particular gear.

So get in shape first then see what gears you can turn.

[diegogarcia]

Thanks for this, have been looking at it in depth after analyzing my Garmin data and conclude that feel I am better off changing back to 50/34 with a 12/25 which is what I was running in 2010 which was a good year.

I think the issue I faced is that paradoxically, I assumed that a bigger chain ring with a relevant cassette would make me stronger and faster and to a point it may have but equally I have found it not really being conducive to my ride to the short legs! As ever it is all about deconstructing previous efforts and working stuff out. I appreciate the stuff on here.

[basilic]

However, I seem to be tiring quicker on the bike with 53/39 than I do on the bike with 52/36.

DG, why to you attribute the tiredness to gearing? I can see it if you tire more specifically on climbs where you mash a 39/25 (3.27 m development) and wish for a 36/27 (2.88 m development). But riding in the big ring on the flat, the 1 tooth difference up front is immaterial. The cassettes are the same for the first 8 gears, with 23-25 tooth cogs at the low end for one, and 24-27 for the other.
How different are your 2 frames? if the 53/39 is overbuilt and stiff, that could play a role.
How different is the usage? if you use one for hard intervals and the other for smell the roses rides, well...