hunterr41

I am in California for the winter and the group I ride with ride a lot more elevation that I am used to riding. I have a SRAM apex crankset with compact gearing (50/34) and 11/32 cassette. There are hills that I can not keep up cadence on. I currently have a 172.5 crank arm. According to SRAM literature, a 165 crank arm is available.

My question is how much a 165mm crank would help me be able to climb the much steeper hills that my group rides on?

rms13

I don't think crank length is the right thing to look at. The crank length you use should never really change it is based on your body proportions and fit

CRANK LENGTH ? Which one? » Bike Fit » Steve Hogg's Bike Fitting Website

bitingduck

It's a sort of odd question...what cadence are you trying to maintain? You're probably limited by your power to weight more than anything else - if you're in your lowest gear (34x32) and can't pedal fast enough, shift up a cog or two. If you still can't keep up, then you either need more strength, more power (not the same thing), less weight, or some combination of the three, which you'll mostly just get with more riding. Crank length is going to have a minimal effect on whether you can keep up in the hills.

valygrl

Shorter crank will make your lowest gear effectively higher (=lower cadence), not lower.

bt

isn't there a point of diminishing returns?

Bunyanderman

I doubt going from 172.5 to 165 will lead you to notice any cadence difference. Maybe if you had 180 and went to 165 you would slightly, but still not worth the swap. A 34x32 gives you quite the easy gear. At 70 rpm you should be a little less than 6 mph (5.8). There are not many climbs that you will need to drop down to 6 mph for longer than a minute. This might be a climb over 10%, I held 6 mph on a 13.5% (34x28) and I am usually out of the saddle.
Try out of the saddle, your gearing is plenty low, unless you wanted to try a 34x42.

hunterr41

I try to maintain a cadence of 80 or greater but can not of steep hills of estimated 7 to 8%. I am riding a lot more hills and trying to improve.

jeff@work

Like valygrl mentioned you'd be going in the wrong direction with shorter cranks, they'd decrease your leverage and make it harder for you to pedal uphill. Moving to longer cranks would make it easier but only slightly. I've changed crank length a bunch, trying everything between 170 and 180... personally i prefer the longer cranks. I'm sure someone could do the math for you to compare them but in my experience a 36x28 with 172.5 cranks feels similar to 39x28 on 180's. So if you want to try cranks go longer just don't expect a miracle.

andr0id

This is not a realistic expectation.
Sometimes you just have to shift to your lowest gear and grind it out.

Maybe you could maintain a cadence of 80 with a triple with a 30 tooth granny and a 32 tooth large cog, but it doesn't seem worth the trouble.

colnago62

Something to consider also; longer cranks make it more difficult to pedal through tighter turns.

bikepro

I agree. Crank arm length makes little difference unless you made a significant change like going from a 175 to 165 or some such. If you have difficulty on hills, lower gearing is the answer.

carpediemracing 

Remember that to go a certain speed up a certain climb in given conditions requires the exact same amount of power.

If you want to go, say, 15 mph up a 6% grade it's going to require the same power, whether you have short cranks, long cranks, you use big gears, little gears, whatever. If it takes you 300 watts, it's going to take 300 watts.

Based on my own experiments with crank lengths, based on experimenting with different gearing, the only time you'll find crank length to truly improve climbing will be on the shorter anaerobic climbs. As more of a flatlander myself, having done a number of "SoCal training camps" (where I visit a friend and former teammate and train for 2-3 weeks), I suspect most of the climbs are more than 20-30-40 seconds long. Therefore my above scenario doesn't apply (it didn't apply for me).

There is an element of muscular endurance, meaning you use glycogen in your muscles. If you spin then you reduce your muscular reserves. I couldn't put a finger on this until someone cited a study where they found that spinning zapped glycogen stored in certain parts of your body.

Basically if you spin all the time then you reduce the amount of anaerobic power available. I use my anaerobic power to help me cheat through the aerobic demands of a climb when said climbs are short enough, like a few minutes. This covers a lot of the climbs I encountered in SoCal, the 1/2 - 1 mile climbs scattered all over the place.

Having experimented on steep climbs with long cranks (175mm) and short cranks (170mm), typically using the cranks for a whole season to acclimate to the difference in size, I found that as soon as I got into the red the crank length makes no difference. I'm just as slow/bad on long or short cranks. I can go faster until I blow up on long cranks because I turn bigger gears at much lower rpms, using my anaerobic power, but once I blow up and have to plod along at about my FTP I'm struggling with a set low power threshold.

I can find some references etc in a bit if you're curious.

LesterOfPuppets

Grinding up hills is slightly easier with longer cranks.

Just choose length that makes a comfortable circle for you to spin, though.

Change gearing to suit the hills you climb.

Jiggle

This isn't a component issue. You need to lose weight. Fortunately, that is free. This post just saved you money.

dtrain

?? For many situations, sure. But with 34/32, he's got plenty of low gears. Stick with it and HTFU is the answer.

dtrain

+1.

dtrain

There you go. That's the only way to do it. Your gear is fine.

FBinNY 

To the extent that it would matter, going to shorter cranks is the wrong direction. If anything (not that I'm suggesting it) you'd want longer cranks for added leverage for hill climbing.

OTOH- consider that a a crank change would make a difference of 2-4%, which is roughly like adding one tooth to your largest rear sprocket, so not exactly earth shaking. Also changing crank length messes with your automatic pedaling circle. This matters more to spinners than pushers, but you're very used to the cranks you have, and changing isn't something you want to do on a whim.

Your cheapest most productive option is replacing the 34t with a 32t for about a 6% drop in your low gear. However that's not all that much, so you might need to consider a triple, or a 34t cassette combined with the 32t chainring.

Keep in mind, that lower gearing may not solve the problem. Climbing at speed is a horsepower issue, so while gearing might help with cadence, it can't magically increase your horsepower. The only way to do that is to ride hills and adapt. It's no accident that some of the best climbers among the pros come from places like Columbia.

Number400

It would be great to do long climbs at 80. My reality is that I on really tough stuff or if I am in the red, I drop my normal cadence and grind it out at more like 50. On a really steep climb, it was so bad that I was 30 and was so far forward that I had traction issues. Lock your arms, rotate your pelvis up and do leg presses all the way up. Your HR and the hill will dictate what cadence you need to survive. I used to have a really high cadence all the time and it has it's benefits but as mentioned above, you may need to train it down to perform well all round and climbing.

Your gearing is the same as mine and works almost anywhere for me. I have made the mistake of traveling and doing mountain rides with the wrong gearing and really beating my knees up.

colnago62

Yes, this is the sad truth about climbing, you can't buy faster ascents. You really can't just climb more hills, either. The only way to improve dramatically one's ability to climb is by losing weight.

dtrain

Weight loss can be a huge benefit to climbing (no doubt). But I also think one can definately get better at climbing by climbing more. You don't think there is a fitness aspect to all this? Better technique(s)?

Hmmm

80 seems high for climbing if you're new to it or if the hill is getting really steep. I would say try to stay at 60-70 in your lowest gear.

After that: HTFU or loose weight.

RJM

The shorter crank isn't going to help you...lower gears will or better fitness in your legs.

What cadence are you trying to stay at that you can't? It isn't unreasonable to have your comfortable cadence drop from, say, 90 on flats to 70 for climbing without any ill effects.

I went from a 172.5 crank arm length to a 165 because of knee problems and they helped me quite a bit. It didn't really change the gearing or how I was pedaling...at least none that I could feel.

carpediemracing 

Ultimately pedal technique and all that simply give the rider something to think about. For example if I focus on pedaling technique a bit more then I tend to be more consistent. When I don't think about it I tend to slow here and there.

However the reality is that climbing is all about weight and power, meaning how light can you get and how much power can you put down.

The issue with fitness is that you're genetically limited to a certain FTP (watts you can put down for an hour) and related numbers (watts you can put down for a minute or 10 minutes or whatever). You can train to get close to your potential but your genetic cap is what it is.

So, for example, my FTP in 2010 was about 220w. It's reasonable to hold 180w for 2 hours, about 90% of my FTP. Difficult but reasonable. I could do 105% of 220 for 20 minutes, but that's a max effort, like I want to climb off the bike and lay down after.

I have teammates and friends that have FTPs in the 300-350-400w range. To go from 220w to 300w is next to impossible for a reasonably fit individual. For me to go from 220w to 400w, I don't think even doping to the max would accomplish that. It's a genetic cap and it's what we all have to live with.

The best way to express weight and power is watts/kilogram or w/kg. This gives you a great idea of how well you'll climb (since you deal with much less wind resistance at the lower climbing speeds). My w/kg is typically in the 2.5-2.8 w/kg range, below that of many riders out there. At my best I was about 3.1 w/kg, like in 2010. If I had zero% body fat (impossible) then I'd be at 3.6 w/kg.

Compared to that a Tour de France winner might be at something closer to 6 w/kg, maybe 6.5 w/kg. It's basically twice my w/kg. There's a reason why those guys are pros - they have a genetic talent/gift that's very rare.

When I lost 29 pounds between 2009 and 2010, and did Palomar Mountain (northeast of San Diego), I went from doing the climb in 2:00-2:05 at 184-185w to 1:51 at 181w. It's not a huge difference considering I was 29 pounds lighter. Sure I was faster but the guys that climb Palomar in an hour flat? They're untouchable from my point of view. What could I do to take FIFTY ONE MINUTES off my time? Not much. I already lost 29 lbs. If I took another 30 lbs off I'd realistically be dead. I can't increase my power by 100%.

Some folks don't climb that well. That's all there is to it.

colnago62

More climbing might make you faster within the group you climb with, but it won't move up to the next group ahead of you on the climb. Weight loss can have a dramatic effect on how you climb, especially considering most enthusiasts have a lot weight they could lose. Ultimately, how well we climb has been determined by our genetics long before we decided to ride a bike.