Crank & Cassette Size

Yamabushi

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#1
Since I started proper road cycling two years ago, I've been riding a full size 175mm, 52/39 crankset, and most of that time with a 12-28 cassette. I admit I initially bought into the "real men" ride full size cranks rhetoric. That being said, overall it's been a reasonably ride-able setup, allowing me to claw my way up nearly everything I've attempted. For example, I made it up both the notorious Mikuni-toge and Kazahari Rindo without any stops or breaks.

Keeping all that in mind, I am nearly decided that I would be better served by moving to a compact crankset. The issue as I see it is that I'm not able to maintain my optimal cadence on the steeper sections. I have to drop down into the 40's on especially steep sections, when I'd really like to be in the 60's or higher. I end up mashing and not really using my cardio enough. I'd like to try a compact 50/34 with my current 12-28 cassette. I believe that would allow me to maintain a more ideal cadence through a wider range of climbs. I believe Alan is running something similar. If it turns out that I really never use the 34/28 combination, then maybe I'd go to a mid compact set up giving me the easiest gearing of 36/28. Regarding crank length, I've been very happy with 175mm but may move to a 172.5mm. I expect that would be a near imperceptible change. In summation, based upon my math and my gut instinct, I think a 50/34 with a 12-28 cassette would allow me to maintain the optimal balance of cardio vs muscle (grunt) on most climbs.

So now I ask, what are you riding? And, what feedback and/or input can you share?
 

FarEast

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May 25, 2009
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#2
The Pro's are stating that there is no real difference in power transfer in regards to crank length - thats what your gears do.

It really is down to personal preferance - as you know I ride compact in the climbs and Im actually looking to replace my 172.5 with a 175 which is the same as my standard cranks.
 

Yamabushi

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#3
The Pro's are stating that there is no real difference in power transfer in regards to crank length - thats what your gears do.

It really is down to personal preferance - as you know I ride compact in the climbs and Im actually looking to replace my 172.5 with a 175 which is the same as my standard cranks.
Yeah, as referenced in my initial post, I don't expect the negligible crank length difference to be a real factor. I just mentioned it to fill out all the information before someone asked. More to what I'm getting after, when you are running compact, what is your setup? What chain rings, and cassette range?
 

FarEast

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May 25, 2009
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#4
Ok well as you know me I change the cassette depending on terrain for racing - however my training set up is 50-34 and 11-28.

It covers everything~ !
 

AlanW

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Jan 30, 2007
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#6
Crank 50/34 compact
Cassette 12-13-14-15-16-17-19-21-24-27

I chose the 12-27 instead of the 11-28 because it avoids the 15/17 jump which is right in the middle of my usual gear range, and also because my legs aren't strong enough to make any meaningful use of an 11 tooth cog :eek:

AW.
 

GSAstuto

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Oct 11, 2009
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#7
For those that are weight minded, actually going 'smaller-smaller' is a little better. I've never had problems with my knees (other than snapping one of them in two) , so I'm not in the 'big gears hurt your knees' crowd and am pretty ok with mashing a larger ring. With that being said, though, once your cadence drops much below 60 you start to roll off torque efficiency rapidly. At the same time, if you ride out of saddle a fair amount, then you stand to gain a little more efficience by larger gearing as the initial 'roll on' is being done by a fairly big muscle and your weight - so pulling more chain through the front IS advantageous. Pantani typically did his climbing in a 44/54, BTW - with a 12 or 14 /25 rear set. But fast forward to much better mechs, chains, metallurgy, etc - and voila, we have really well working 10 and 11sp systems that can handle up to 18-20 teeth capacity! Amazing!

I'm now running a 36/51 with 11/28 rear cassette and absolutely loving it. Perhaps the only thing preventing me from going to a 'full compact' is just my ego and the fact I had a spare CX crankset sitting here. I did like the 38/53 combo as well - but on the gutbusters like Azami Line - hey, why bother. If you got the gears use them for chrissakes! Unless there is some specific reason to suffer - like Vintage Throwback Challenge, Fixed gear, etc - then I say gear as wide as you can.

I only wish Shimano would start stocking their new CX6700 cassette - I've had several on order for quite some time. They are 12-30 and a great, economical cassette. (Hidden jewel - like the CX70 crankset) And they work just fine with 105, Ultegra and DA rear mechs, btw. Though chain tug does get a bit tight on the BIG BIG if you are running more than a 50T front.
 

Jayves

Speeding Up
Nov 20, 2009
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#8
For a guy like me who doesn't have the top end power to match the pros as well as muscular endurance, I'm happy that I can always call the services of my compact cranks and 32T setup when needed :) sure, there are big gaps between gears making it difficult to find the right cadence sometimes but it doesn't really bother me. I'm happy to just sit down and spin and breath hard as I can... rather than hit with a lactic pain for the next hill after a refreshing descent :p
 

Yamabushi

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#9
Crank 50/34 compact
Cassette 12-13-14-15-16-17-19-21-24-27

I chose the 12-27 instead of the 11-28 because it avoids the 15/17 jump which is right in the middle of my usual gear range, and also because my legs aren't strong enough to make any meaningful use of an 11 tooth cog :eek:

AW.
Thanks for the clarification, Alan. As for the cassette, your reasoning is exactly why I use the 12-28. I want the 16t, otherwise the gap between 15t and 17t is too big! So my cassette is 12-13-14-15-16-17-19-21-24-28, exactly the same as your except I have a 28t in place of your 27t. That gives me pretty even spacing as I work my way through the cassette.
 

Mike

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Sep 24, 2007
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#10
Pete, on both my bikes I run 172.5 cranks and 12-28 cassettes, but have a standard and compact chainset for each. Obviously the compact is my mountain goat and the standard is more of an all rounder.

I only recently changed over to the compact and it sure makes a difference on steep climbs. I can now get over them with a good cadence and not feel like my knees are about to implode:confused:

Considering where you usually ride, I can't recommend getting a compact enough! You'll love the difference.
 

Yamabushi

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Jun 1, 2010
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#11
For those that are weight minded, actually going 'smaller-smaller' is a little better. I've never had problems with my knees (other than snapping one of them in two) , so I'm not in the 'big gears hurt your knees' crowd and am pretty ok with mashing a larger ring. With that being said, though, once your cadence drops much below 60 you start to roll off torque efficiency rapidly. At the same time, if you ride out of saddle a fair amount, then you stand to gain a little more efficience by larger gearing as the initial 'roll on' is being done by a fairly big muscle and your weight - so pulling more chain through the front IS advantageous. Pantani typically did his climbing in a 44/54, BTW - with a 12 or 14 /25 rear set. But fast forward to much better mechs, chains, metallurgy, etc - and voila, we have really well working 10 and 11sp systems that can handle up to 18-20 teeth capacity! Amazing!

I'm now running a 36/51 with 11/28 rear cassette and absolutely loving it. Perhaps the only thing preventing me from going to a 'full compact' is just my ego and the fact I had a spare CX crankset sitting here. I did like the 38/53 combo as well - but on the gutbusters like Azami Line - hey, why bother. If you got the gears use them for chrissakes! Unless there is some specific reason to suffer - like Vintage Throwback Challenge, Fixed gear, etc - then I say gear as wide as you can.

I only wish Shimano would start stocking their new CX6700 cassette - I've had several on order for quite some time. They are 12-30 and a great, economical cassette. (Hidden jewel - like the CX70 crankset) And they work just fine with 105, Ultegra and DA rear mechs, btw. Though chain tug does get a bit tight on the BIG BIG if you are running more than a 50T front.
For a guy like me who doesn't have the top end power to match the pros as well as muscular endurance, I'm happy that I can always call the services of my compact cranks and 32T setup when needed :) sure, there are big gaps between gears making it difficult to find the right cadence sometimes but it doesn't really bother me. I'm happy to just sit down and spin and breath hard as I can... rather than hit with a lactic pain for the next hill after a refreshing descent :p
Pete, on both my bikes I run 172.5 cranks and 12-28 cassettes, but have a standard and compact chainset for each. Obviously the compact is my mountain goat and the standard is more of an all rounder.

I only recently changed over to the compact and it sure makes a difference on steep climbs. I can now get over them with a good cadence and not feel like my knees are about to implode:confused:

Considering where you usually ride, I can't recommend getting a compact enough! You'll love the difference.
Cheers Tim, Jose and Mike! That's exactly the type of feedback I'm looking for! And I'm with you Mike, if I was only doing the occasional, moderate climb then I'd likely just stick with the full size, but this year every ride has been a 2000-3000m adventure with more than a few extra steep ones thrown in for sh*ts and giggles!
 

TOM G

Speeding Up
Jun 13, 2011
102
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Minato
#12
Pete -- I just swapped out my standard crankset for compact three weeks ago, after suffering up Mikuni with the standard. So, my current setup is 50/34 chainrings and 12-27 cassette. This gearing is working well as I can spin better up the climbs and it doesn't knock so much out of me. The biggest difference is I can recover better for the next successive climbs than I could with the standard. Go compact... You won't regret it.

Tom
 

m o b

Speeding Up
Jun 22, 2008
341
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Bremen
cyclitis.wordpress.com
#13
I did the math:

A 39 front and 28 rear gives you a speed of 7.1 km/hr on 700C tires at 40 rpm cadence. If you go to 34 front and 28 rear and pedal at 60 rpm your speed would move up to 9.2 km/hr. So if you can keep the speed - good.

If you would go at the same speed of 7.1 km/hr and pedal at 60 rpm, you would need a 36 rear cog with the compact crank.

From previous experience (Kazahari Rino, Mikuni, Nennogon) a compact crank is a good idea. I never had the feeling that I am loosing the top speed of a 52/11 combination.

An even better idea, purely from the point of gearing choices for steep Rindos, would be a tripple front crank. However that would require even more investment (derailleurs, Left STI lever) and looks rather uncool. Come on, with a tripple crank you are not taken serious any longer. A compact is the almost invisible and best choice.

Crank length had been discussed many times in great detail, for example here:

https://tokyocycle.com/bbs/showthread.php?t=2878&page=4

I am riding 52/16 fixed or 52/18 single speed and 52/40 with 12/28, but these are North German flatlands here. Don't even know crank length.

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Resized. Sorry for the inconvenience caused.
 

Phil

Maximum Pace
#15
mob, is it possible to resize that pic? Horizontal scrolling hell on the laptop :)

I've been on a compact for a long while now (in fact, my first road bike was a triple). Don't really need the 34 here in Boso, but I actually like the 50 more than the 52/53; means I can sit in the big ring all the time, even in heavy headwinds, and save the inner ring as a bail-out gear.

34 front, 23 (11-23) back is fine for Boso, as even though the climbs can be quite steep they are usually short so it's fine to power up them. (This is the same combination I had in LA, and it was also okay--there are some very, very long climbs there but almost all of them shallow (<6%)).

34 front, 25 (12-25) back was perfect for Tomin no Mori and Matsuhime two weeks ago.

34 front, 25 back was NOT perfect for Deej's temple loop in the Chichibu--I was struggling for more reasons that just gearing, but even in the best of shape 34-25 would not have been optimal for those hills. Definitely wanted at least a 27 and probably a 28 would have been nice.

Don't know if it's been mentioned above, but a 50-11 is a bigger gear than 53-12, so "losing the top end" is not usually a good reason for avoiding a compact.

The one clear disadvantage that I experience with a compact is when shifting to the inner ring mid-way up a power climb, say, out of the saddle, while trying to maintain speed (hang on to a wheel). With a compact, the initial drop-down usually leaves me spinning too much until I manage to drop down a cog as well, losing a revolution or two of power to the pedals, and often as not slowing me down enough to lose the wheel I'm chasing. Of course, this is a fairly uncommon situation and hardly offsets the advantages of having that lower gearing.
 

Quicksilver

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Jan 9, 2011
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#16
Pretty much echoing what others have said, but I changed from 72.5 cm cranks on a 53/39 chainset with 11-28 on the back to a 50/34 compact with 70cm cranks for hill climb races earlier this year. Apart from having to put the saddle up slightly, I couldnt notice any difference related to crank length but besides the real advantage of having a whole gear lower for the really steep climbs I find that I use a much fuller range of the gears when riding in the hills. You can also avoid going down to 40 rpms easily even on Mikuni.;) Still, like Mike, I think it is good to have both options and for flatter terrain I would gladly go back to the regular chainset and even the 11-26 cogs the bike came with. Fourtunately, if you dont mind having to change the front deraileur height a little, changing cranks is a pretty easy operation mechanically:warau:
 

joewein

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Oct 25, 2011
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#17
An even better idea, purely from the point of gearing choices for steep Rindos, would be a tripple front crank. However that would require even more investment (derailleurs, Left STI lever) and looks rather uncool. Come on, with a tripple crank you are not taken serious any longer.
This is the beauty of my 20" wheel Bike Friday - I don't have to worry whether I look like a "real" road cyclist with something like triples ;)

From experience I know that my knees give me trouble if I "grind" instead of spinning, so I spec'ed my bike with triple cranks (50/39/30) at the front. I use an 11-28 9sp SRAM PG-950 cassette at the rear. The extra small chain ring is on top of the 4:3 mechanical advantage the smaller diameter 20" 451 wheels already give me. My lowest gear of 30/28 corresponds to something like a 30/37 combination on a 700C. So when I hear "real" road cyclists discuss climbing gears, I just don't know how you do it! I actually do most of my riding in the middle chain ring because it gives me the widest range of usable gears without chain noise.

According to Sheldon's gear inch calculator, my range is from 90.5 in the fast 50/11 combination to 21.3 in the 30/28 climbing gear. I tend to drop down into my smallest gear once speed drops below 10 km/h or so. Until I crawled up the steeper sections of Takayama at 5 km/h, my slowest had been 6.5 km/h on some sections of R18, R35 and Matsuhime North Side.

My guess is, your legs put out a lot more torque (seeing your gearing) and more watts (seeing your climbing speeds).
 

Deej

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Oct 13, 2007
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#19
50/34 and 12-25, on Campy Chorus 11-speed.

This setup has served me well so far, but I'd like to see how 27 feels on the really steep stuff.
 
Jun 9, 2011
241
1
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tokyo
#20
if you can get your hands on one i'd suggest test riding a 170mm crank set. i used to ride 175mm on everything but after switching to 170mm on my bmx about 10 years ago riding anything longer make feel like i'm going crazy. i find that 170mm is much more comfortable to spin and as i recall we're pretty close in height, so maybe 170mm will also work for you.