Gearing - Do I need a compact

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bigfatty
Posts: 135
Joined: Sun Sep 28, 2014 11:53 am

by bigfatty

I was just out on a test ride to see if I could do with a compact crank.
I rode a 900m climb, of which 8km was at 7%. I spun a 39x23 gear at 70rpm with out getting into any trouble.

According to some studies of TdF riders here is an excerpt on average cadence on Cat 1 and HC climbs

"The “climbers” had a higher power output and cadences in both Cat 1 (321 W, 75 rpm) and HC (311 W, 71 rpm) than the “helpers” (292 W, 71 rpm for Cat 1; 287 W, 69 rpm for HC)."

source: http://www.pezcyclingnews.com/toolbox/p ... C2Eb-IR2PI

seeing as I could lose a couple of kilos and I'm only just getting into riding with a club, I think I could push my cadence up to 75rpm in the near future, so I could probably just get away with a new 27t cassette?

Somebody told me I should be spinning a higher cadence up hills but I think the studies prove this is not reality and is only another armstrong myth.

I would invite feedback on whether a compact is really neccessary.

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eric
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by eric

I do a lot of climing and climbing races. Cadence is a personal preference. Some people do best at higher cadendces, others can handle lower cadences. Low cadence tends to tire the muscles faster. But some of the faster climbers I know use relatively high gears and low cadence.

Generally heavier riders seem to prefer higher cadences and lighter ones can get away with lower cadence but that's a gross generalization.

Also realize that doing a single climb when you're fresh is different from doing the same climb after 4000 meters of climbing that day and 4500 the day before.
And getting up the climb is different from racing it like the (race leading) pros do in a mountain stage of the tour.

You have a lot of room for lower gearing with your current chainrings. Unless you're planning on doing some big climbing rides or steeper climbs or some other large increase in your climbing you can get by with a larger cassette. If you find that's not low enough then get the compact.

martinko
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by martinko

Pushing high gear and lowering your cadence may also lower your heart rate. That's what I do if I need to keep speed but calm down a little bit.

davidalone
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by davidalone

I would argue that the vast majority of riders could use a compact and be way better. it is difficult to tell from one ride. A higher cadence recruits your aerobic system more, while if you're spinning at lower cadence you're expending muscular strength. You 'might' be okay for one hill but you won't last long if you're using a 39-23 living in a mountainous area- and I mean real mountains, where you have rides that are uphill for 30, 40km. simply because sooner or later lactic acid is going to start to hurt- your aerobic system will be more effecient.

Even protour riders use compacts when going up the really steep stuff. Contador put a 34-32 on his bike a few years ago at the Giro. I've seen Even High level riders (state masters champions) rides compact.

ultimatel the answer us going to depend largely on what sort of rider and what terrain you have. if you're super strong and have mostly flat terrain then a 53-39 might suit you. for someone living in the rockies who's thin but with a big engine maybe not. I ran a 50-36 on my crank for half a year. it certainly didnt hold me back, I just rode everything in the big ring.

In my own experience compact is definitely the way to go if you aren't a pro and pay for your own equipment. It's way more versatile. you can go from a 50-34 to a 53-38 on a compact crank if you wanted, or run a mid-compact 52-36. the new shimano 4 bolt crank allows you to do this as well. not so with a standard 5-ring 130 standard.

jpanspac
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by jpanspac

Another factor is how fast you want to go down the hill. You'd spin out a lot sooner with a compact crank. If you're content to coast down it doesn't matter so much.
My favorite components are the ones I never have to think about.

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Rick
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by Rick

Since I am an extremely mediocre (OK...poor) climber I have been fascinated by this. I get the opportunity to ride with some seriously good climbers and I am always mystified that they range from "jabbing like a runaway sewing machine" at 100 rpm, to "grinding at an almost imperceptible cadence") at about 50 RPM. (Of course they are all very skinny!) So I have tried both, and I try desperately to train so as to extend my range of usable cadences to try to find what is most efficient and powerful.
The only thing I have learned is that you have to find your own cadence. Riding with other people, faster than you, will really open your eyes, because what feels best is not necessarily really best. And what you think is as hard as you can go is not as hard as you will be able to go with a combination of testosterone and adrenaline dumping in a real race.

It sounds like you are a pretty good climber, so I would first try the 27 cog. You could even go bigger if necessary. I am using a compact and even have a 32 tooth cog, but just for training. I usually end up using a 27 max. There is no harm in owning a few different cassettes. I don't find any disadvantage using a 50-11, even on downhills. You are usually coasting or drafting when going that fast, so the need for a 52 or 53 is a non-issue for me.

So I am a big advocate of the compact, but because I know I NEED it. If you are a good climber, you probably don't NEED it. But there are a lot of high level pros using compacts, so it is certainly no disgrace.

dunbar42
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by dunbar42

I wonder if those pro cadence numbers are just for the climb? According to Strava my average cadence on a mixed ride (flats + hills) is around 70rpm but I rarely drop below 80rpm when I'm pedaling. And when I'm climbing at FTP I'm doing more like 90-100rpm. My Garmin is set to include zeros so coasting brings the average down.

I do think it comes down to what sort of cadence you normally fall into when climbing. I use a 50/34 with an 11-28 11sp cassette and I recently tried a 36T small chain ring. I lasted about 10 days before swapping back to the 34. What I found was the lowest three cogs were fine (36-28; 36-25; 36-22) but once I got into the taller gears (36-19 and higher) my cadence would bog down into the 70's. I just didn't feel like I was on top of the pedals. I can't imagine what a 39T small ring would feel like on anything more than a 5% grade.

Svetty
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by Svetty

The issue for me is what gradient climbs I need to be able to ride. I can grind up almost anything with a 39:25 but for anything over 20% find a 34:25 more suitable. Most of the time I find a 52/36 chainring combo best for all round riding as there's not much I can't manage with a 36:25 and I have a variety of wheelsets with different cassettes for flatter or steeper rides.

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bigfatty
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by bigfatty

My preferred climbs are 5km - 10km and about 7%.
Reason I am asking is down to cost as I run Campagnolo and I would in March like to get a stages power meter (only if I keep up the training over winter, as a reward, but not if I fade out from training) so that leaves me with the choice of FSA and with my budget, limited to either compact or standard.
I think I will go with 39x27 after looking at http://www.bikecalc.com/gear_ratios .

I will look at cadence speeds of my fellow riders on the next climb but for me 70 is a good mix of low aerobic and low muscle fatigue, with training I can hopefully up this to 80 in the same gear.

Thanks for the response, it is a very interesting read.

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bigfatty
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by bigfatty

dunbar42, if I remember correctly, cadence is just for climbs.
also you can check Valverdes cadence at http://www.srm.de/news/road-cycling/le- ... e-stage-9/ . he averages 79rpm on a 7% slope. I guess with his weight and power output he is pushing a 39x19

Marin
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by Marin

Going from your nickname, I estimated you at 180cm and 85kgs.

39x23@70/min is 15kph, which means on an 8% slope you're pushing out around 350 Watts -not bad.

I'm a bit lighter (79kg), but when I did a 1000m climb in around an hour a few weeks ago, I was extremely glad that I was on my CX with extra low gearing. I could never push 39x23 uphill , my knees would kill me. I ride compact with 11-28, and I put on a 11-32 for the mountains...

fallzboater
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by fallzboater

I'm old-school so my summer bike has a 53-39, mostly out of pride. I have used compact on rentals and I spend a lot of time on my winter cross bike with slicks and 46-38 rings. One nice thing about smaller rings is that you can stay in the big ring longer up moderate slopes. I think people who ride in flatter terrain also benefit from compact rings, they don't have any use for a 53/11. I have long descents and on group rides I appreciate not being completely spun out at 45 mph, but I don't really need it.

wingguy
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by wingguy

bigfatty wrote:I was just out on a test ride to see if I could do with a compact crank.
I rode a 900m climb, of which 8km was at 7%. I spun a 39x23 gear at 70rpm with out getting into any trouble.

I would invite feedback on whether a compact is really neccessary.


Is it a constant 7% or is the gradient quite variable?

7% average for a long climb is reasonably steep, 7% peak gradient is not. What do you want to have in reserve for the ramps?

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by spdntrxi

Better then I can do.. 7% I'd be in the 23 also but 34 upfront..[emoji4]..
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bigfatty
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by bigfatty

Max is 10%. Average is 7%. But more or less a pretty steady mix of 6,7,8% according to the garmin.
Lowest cadence was 62 when it ramped up to 10%
75rpm is nice tempo for me so would be happy to keep this up on the ramps.

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