Convert to compact crankset?
 

Hi,

I'm currently running a 53/39t Shimano 105 5700 drivetrain on my road bike, and plan to do some serious climbing this year. I've done 14-15 % climbs with this gearing (mostly shorter climbs), but in this area, you can climb 100 ft for every 10 mi ridden. Would it be beneficial to go with a compact crankset?

Would it be possible without changing derailleurs/shifters? Got a 11-28 cassette in the rear.

Dave

I've converted bikes with 53/39 and 52/36 to 50/34 with no issues. I think the 50/34 compact is more useable, at least for me.

You don't need any change out anything else, though you'll have to adjust your FD, including scooching it down for the smaller rings, and maybe lose a few chain links.

And so the first question is CAN you lower the F derailer ?.

If a clamp design, no issues, if braze on you might need an adapter, not sure how well those work.

I'm currently using a braze on front derailleur with a adapter to clamp it to the seat tube. Is that what you meant?

Dave

Did you mean 1000 ft for every 10 miles? Otherwise you're saying a typical 50 mile ride only has about 500 ft of elevation gain? I'd say there probably wouldn't be too much benefit for you switching your crank, if you're able to get over the short 14% humps that I guess you come across.

Yes, 1000 ft for every 10 mi. Even more if I go North towards the Cohutta mountains.
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Got 15,000 ft of climbing for the year already.

Dave

Yes, a wrap around clamp, even with the adapter for a braze on derailer, is easily lowered.

Usually.

Sometimes things like bottle cage bolts are in the way.

Good idea. May need to adjust FD as above and shorten chain a smidge.

There should be a bolt that attaches the front derailleur to a fixed bracket with a vertical slot to enable sliding the FD up and down. Easier than the locking collars on most steel frame bikes.

I've swapped chainrings and cassettes/freewheels around to suit my fitness and terrain. My routes are roller coasters, no serious long climbs, mostly lots of short steep hillettes. Around 500 feet of elevation gain every 10 miles, so typically 1,000-3,000 feet on my usual rides. I can get by with an old school 52/42 double and 13-24 freewheel/cassette, but I'd rather have some bailout gears for days when I'm tired or the headwinds are usually stiff (pretty much all winter and spring).

By the time I hit age 60 I realized I'd need to swap gearing around occasionally to suit my current "feels-like" gauge. Or have at least two road bikes set up for either go-fast or go-long days. So the '93 Trek 5900 had 52/42 Biopace chainrings (which I liked on that bike, but didn't care for on another bike -- probably minor differences in geometry, crank length, etc.) and 13-28 freewheel; and the '89 Ironman was switched from the original 52/42 and 7-speed 13-24 to 50/38 chainrings and 13-28 freewheel.

With that gearing the Ironman has been a great bike for casual and tempo pace solo and group rides, but I'd spin out on some downhills. No big deal. But for the moment the Trek 5900 is out of commission (time to service the nearly 30 year old Chris King headset, which was badly neglected). So I've been redoing the Ironman gearing.

I tried the same Biopace 52/42 on the Ironman. Worked great on the Trek with 170 cranks. But I just could not get along with the same chainrings on the Ironman with 172.5 cranks. Can't put my finger on it, but it felt too surge-y and herky-jerky, rather than the smooth transition to the elongated lobes that gave me a bit of leverage and oomph on climbs with the Trek. After a couple of weeks my right knee was twinging a bit. I couldn't find a setup of saddle angle, fore/aft or height that suited me on the Ironman with the Biopace.

So last night I switched the Ironman back to the original Suntour 52 big ring and a Vuelta 39T small ring. A few tweaks to the front derailleur locking collar. Same 13-28 freewheel I've been using for about a year. Felt great today on a 36 mile ride, with lots of rollers. Not my fastest ride on a favorite 6-mile time trial route, and today a fast group working a paceline bumped me out of the top ten on Strava to 14th. Ah, well. A couple of years ago I had 2nd place, but I knew it wouldn't last with just little old me riding solo. I doubt any combo of gearing would have mattered. I need a younger engine and legs.

I have a 2011 Diamondback Podium frame on the workstand at the moment, waiting to be built up. It came with an Ultegra 53/39 crankset, so I'll use that for awhile. It's not original spec (I think Diamondback used SRAM and FSA for their Podium series), so I guess the previous owner switched to Ultegra. And I have a 10-speed 11-25 Dura Ace cassette, so we'll see if I can handle that combo. I suspect I'll need to change the Ultegra crankset to 53/38 or smaller little ring. But the lightweight frame might surprise me and make it possible for me to climb with that combo.

I'd say for that terrain yes. I have my bike set up with a 50x34/11x32 for riding in Greene County area of the northern Catskills in NY. Avg rides are 1mi/100ft, which this gearing is perfect for IMO. There's not many long climbs here, mostly ~1mi or so stuff, and plenty of short steep rollers into the teens my 34x32 gets a fair amount of use. Our place is up around ~2,000ft too, so the climb home is usually the hardest part of any ride. Also the granny gears come in handy for unpaved stuff too.

I think 53/39, 52/36 and 50/34 are pretty much the standard trio that most bikes should be able to handle any of them without requiring additional modifiers to the FD, such as FD extenders and the like.

That said, I think changing the cassette (e.g. to a 11-34) would provide a bigger impact, though that may require changing to a long cage derailleur and a longer chain. Or ideally, change both. :innocent:

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If you're bottoming out your gearing to where you're not able to modulate your efforts the way that you want, yes. Possibly even smaller than a 50-34, depending on how badly you might bottom out, how much you care about keeping your cassette closely-spaced, and how much top-end you have real use for.

Only you can answer that. Do you have the strength to use the current set up? Are you struggling doing the 1,000 ft per every 10 miles? Does your conditioning not allow you to use the current set up? Do you need lower climbing gears.

1,000 ft per 10 miles is not that much. Around here and 8 mile climb gives one 2,300 ft of gain. When I was training for climbing rides, it was no problem on a 53/39- 12/26 cassette.

I also did a ride with 12,000 ft in the first 72 miles.

Not saying anything about your fitness or strength. Only that YOU ask if you should swap to a compact. Only you know the answer.

My opinion, if you are training as you say, you shouldn't have a problem with that type of gain. If you feel you need it, then yes! Nobody can answer that but you.

It depends on how strong you are.

For reference: I regularly do climbs over 12% sustained and peaking between 15 and 20%. A particular climb I do at least once a week is 3km long, min gradient is 15% and max 20%. I'm running a 50/34t with a 11/32t cassette. I can climb them with this gearing, but I must admit that using the lowest gear I'm around 50rpm and 95% of my max bpm on the hardest parts. I'm seriously considering using a 11/34t cassette, although I'm not keen on the increased gaps between sprockets and have been holding back because of this, since such climbs, although frequent, are only a "short" portion of my rides.

I can do the same climbs using a 28 cassette, but my legs feel knackered afterwards since it forces me to either pedal standing up at a really slow cadence or ride at a higher speed which I find it difficult or impossible to sustain, especially in hot weather.

Sometimes I also use the 34-32 low gear on more modest climbs, maybe around 12%, when they are long and I feel my legs tired because I've been riding for long, or I've been riding hard.

and... a new rear shifter. Got a 10 speed now :innocent:

well, honestly, I probably don't need a compact crank. Just thinking it might be nice since i'm climbing so much this year. Had my best mileage (and over 150,000 ft of climbing last year) and so far this year is looking to be at least as good,

I'm looking to climb the ten largest climbs (according to wikipedia) in Georgia this year. From what I understand, some of these climbs are gravel, so at least a few of them will be on my mountain bike with 26gi. Here is the list and elevations (there are two tied for 10th):1 Brasstown Bald 4,784 ft

2 Rabun Bald 4,696 ft

3 Dick's Knob 4,600 ft

4 Hightower Bald 4,568 ft

5 Wolfpen Ridge 4,561 ft

6 Blood Mountain 4,458 ft

7 Tray Mountain 4,430 ft

8 Grassy Ridge 4,400 ft

9 Slaughter Mountain 4,338 ft

10 Double Spring Knob 4,280 ft

10 Coosa Bald 4,280 ft

In theory, this is an interesting goal. In practicality, not so much. A lot of these mountains don't have roads that go up. This is just to give you an idea of where i'm at.

Dave

A 34F/28R gives you a low gear ratio of 1.21, your current low gear is a ratio of 1.39 so it will be easier. But if you pedal when going fast down hill you might not like what the 50/11 combo feels like.

Changing cassettes to a 11-32 might give you acceptable results with a low gear ratio of 1.22 and preserving your current high gear. Of course there will be some shifts that will have more change in ratio. However depending on you, it might be a non-issue.

You will need to check if your rear DR can handle that big a cog. My 105 5800 can. Cassettes aren't that expensive and are easy to change. Depending on your crank, chain-rings can be inexpensive or some require a new crank entirely.

Ah, those are the highest peaks in Georgia. I myself don't think you would need one but it all depends on your comfort as you say.

I've done this ride on my standard crank. I believe Onyx Summit is the highest "PAVED" road in our area 8,400 ft/ the ride was 12,000 total gain in 72 miles. Also 4 other times on another ride coming from the opposite direction. I didn't feel I needed the compact myself.

But again, it's your comfort zone is what matters. :thumb:

Out here in California, we have some pretty good peaks with paved roads.

https://cimg2.ibsrv.net/gimg/bikefor...7954b50d6a.jpg

​​​​​​That looks like my kind of ride! Sign me up lol. Here in GA there is a race called the Death March. I believe it's almost 100 mi of gravel and 10,000 ft climbing. That's on my list for this year

I guess suffering is good lol.

Dave

Sounds like a great ride. I hear about gravel rides lately but here in the concrete jungle, not sure if they exist but it sure sounds cool! :thumb:

50x11 will get descending fast enough to where you hit the point it’s more efficient to tuck and coast.

I’ve done Pro1-2-3 races, and descended in Alps, Pyrannees, Colorado ( and Hogpen and Brasstown in the OP’s neck of the woods) and have never been limited by the 50x11. ( time trials aside, which is a different issue.)

I'm not touting actual performance positives and negatives concerning the 50x11 vs 52 or 53x11. I'm just letting the O.P. know that it'll feel different to the point they might not like the feeling.-- if they regularly use their 53/11.

The ratio of 53x11 is 4.82 and 50x11 is 4.55, not a big difference. However I don't find that I can max out every downhill to "tuck and coast", in my area and I'm glad to still have a 52x11. I'm not competing on any level. I just ride for me.

I haven't really used the 53x11 as I'm a mere mortal lol. Found out last night my buddy had an extra ultegra compact crankset laying around, so I'll probably try it. This will drop my low gear from 37gi to 31gi.

Road my mtb in a hilly area with 26 gi, and it was a pretty big difference when climbing hills. If I really want to, could change the cassette from 11-28 to 11-32, but that would probably mean larger gaps between gears.

Dave