Bicycle Mechanics - Are chainring swaps "trivial"?

Is it a simple, easy, and a quick operation to swap a 53/39T and a 50/34T back and forth on the same bike depending on anticipated riding terrain? Or, does the derailleur need to be adjusted every time a swap is made, (the front derailleur is a braze-on, so can't be moved up or down on the seat down tube.). The cluster is easy enough to swap out, but I'm not sure about the cranks. Assume same crank length and level of components, (i.e., Dura-Ace 7900, 175mm).

Derailleur needs adjustment.

Also, there are a few derailleurs now designed for 'compact' road cranks - that is, they are ideally suited to smaller chainrings. I suspect the reason for the 'compact' FDs is because shifting can be fussy when using a derailleur designed for 53/39 on a crank with 50/34.

Also, most braze-on fron dreailleurs still have an inch or so of height adjustment - the braze-on has a long slot for mounting the derailleur.

FWIW, this is sort of an unusualy strategy. Riders who need widely different ratios depending on the ride usually change the rear cluster, not the cranks. You can have a 11-25 for flat rides and 13-34 for hilly ones (but you might need a MTB rear derailleur to handle the larger cogs).

The title and body of your post seem to conflict. Are you talking about changing chanrings on the same crankset or will you have both a standard and compact crankset to change between. the 50/34 chainrings will not fit on your standard double.

I'll mess with just about anything on a bike, except headsets and bottom brackets, and sometimes I'll adjust a headset. Part of the reason is I don't have the tools. Part of it is they need maintenance less than any other component. But I know some people re-pack their bottom brackets after every ride in the rain, so what's your threshold for "trivial?"

Go take a chilled 1-liter Mountain Dew to your LBS's mechanic, and ask him to explain what's involved, and what tools you'll need to do the swap. It isn't trivial for me, but maybe it will be for you.

I agree with Re-cycled... big difference between changing chainrings and changing cranksets. U can NOT put a 50/34 chainrings (compact) in a 53/39 chankset. The BCDs are different. U can put a 50T in a regular crankset tho, but not a 34, thats why they came up with compact, CT cranksets.

If you want to change the cranksets, yes is trivial, U need to have another chain for the 50/34 crankset, obviously is like 2 or 4 links shorter. Besides the chain, it can be done in 10 minutes.

The title and body of your post seem to conflict. Are you talking about changing chanrings on the same crankset or will you have both a standard and compact crankset to change between. the 50/34 chainrings will not fit on your standard double.

Sorry for the confusion. The bike in question has full Dura-Ace with a 175mm 53/39T crank. I've changed the OEM cluster from a 12-27 to an 11-27 easy enough, (just remove the 16T, 16T spacer, and 12T "lock" ring and sub in the 11T and 11T lock ring). To go with a 11-28 (maximum available Dura-Ace) or 12-28 would entail purchasing a whole new cluster. That's a lot of bucks for just one tooth in the back. Dura-Ace makes two cranks, (in their respective lengths), the regular 53/39T and the compact 50/34T. Larger rings are available, up to 56T, but they would be a special order from your LBS and you'd probably have to change the small ring at the same time. The chainrings can not be swapped between the two crank arms due to "bolt circle diameter", (i.e., 130mm for the FC-7900 and 110mm for the FC-7950).

I'm at the age, (turn 60 this summer), when there are times that I need a little extra help getting up some hills. Since 39-27 is the max right now for me, I was thinking on these long, hilly centuries, that 34T on the front would give me that extra boost I'd need on those long rides. I'm also hoping to assault Tioga Pass and the grade from the valley floor up to the top of Sequoia this summer.

For a whole lot less money, I could go with an Ultegra cluster to get that extra tooth on the rear. I'd still have the 39 on the front if I couldn't swap cranks. Not sure how much extra that would get me.

Shimano only makes one Dura-Ace front derailleur for use on either crank, (part number FD-7900-B). Their spec sheet says 50-56T for the "Top Gear Teeth" and a "Maximum Capacity" of 16T. Maybe I'd get lucky and going to and from 53T to 50T wouldn't require much, if any adjustments of the FD.

By "trivial", I meant a 5-10 minute; loosen this, loosen that, turn here, adjust that ... and be done.

Thanks for the help in insight so far. It's been helpful and useful in what I might be able to do.

U want to change the cranksets. yes it can be done in 5 minutes and 5 more minutes to put a second chain.

As for the front derailleur, I had a 105 that worked with compact and regular cranksets, and sincerely it would not surprise me if the dura ace would do it too, well knowing shimano maybe not.

What I would do is to find a FD that works with both cranksets, I would advice you just put a campagnolo one but what I dont know is if it will work fine with shimano, maybe sram makes one? I'm not a shimano person so I'm getting in stuff i don't know but for sure somebody else have done it or done this. But clearly u need a FD also that works with both cranksets.

Good luck.

My road bike uses a campagnolo centuar FD actuated by ultegra brifter. Shifts are precise and there is no extra rub.

I think I'd rather get a triple than swap cranks every couple of months (weeks?) depending on what ride I was doing.

My guess is you can switch to a compact and just leave it there for all your riding. 50 x 11 is still a pretty tall gear for most of us. My tallest gear is 50 x 12, and it's fine for fast group rides. At a cadence of 100, you'll go 32 mph. With a 50 x 11 at 100, you'll go 35 mph. Any faster than that for me, it's time to tuck and coast anyway.

Swapping out cranks on a regular basis is a bad idea. It will require lots of fiddling and it will be hard on the cranks.

It sounds like the ideal solution is one of the following 2 options:
1) Leave the compact crank on the bike all the time
2) Get a triple crank if you want low gearing and really want a 53t large ring

I would not get so hung up on DA and get myself a triple. The air is pretty thin up there.

If you get yourself a compact crankset you will have 34/27, that's pretty close to a 30/25. You can get yourself a 110 BCD 53t chainring and swap it out. You will have to optimize your chain for 34-27, but I don't see why your drivetrain should not work between 53/11 and 53/17 or maybe 53/19.

My bike has a 50/39/30 with a 12-25 9-speed. It seems fine for just about anything. A lower gear than 30/25 would seem pretty ridiculous. A higher gear than 50/12 might occasionally get used downhill, but I don't find myself getting dropped for lack of a high gear. That happens on the uphills, no matter what my gearing.

I'm thinking you're not going to be happy making that swap frequently.

It's easy enough to swap the crank and chain, but the front shifting is going to change. Compact doubles aren't, even at best, the smoothest shifting combination due to the wide range between chainrings. Starting with the disadvantage of a too high mounted front derailleur is going to make the shifting even worse. When you change the position of the front derailleur it affects the other front derailleur adjustments.

Good advice, all. Thank you very much. You've helped me make up my mind on which way to go. I'll just keep both bikes as they are now. The other year I ordered the Madone with a triple (50/39/30 and 12-27). The bike shop really tried to steer me to a compact, but I wanted a triple. My money ... so I got what I wanted. I didn't then, nor do now, buy his argument about "too much overlap". I changed the 50 to a 52 easy enough and dropped in an Ultegra 11-28. That bike is set pretty well for the steeper hills, it's just that the component mix is not the best, (i.e., lightweight). It came with a 105/no-name mix which I'm slowly changing to an all-Ultegra or a Ultegra/105 mix.

The Kestrel came with a 53/39 and a 12-27. I modded the DA 12-27 to a 11-27; and it would be too expensive to go to an 11-28 if I stay DA. Dropping in an Ultegra 11-28 would be a lot more cost effective and something I'm seriously considering. The RD spec says it can handle an 11-28.

I've decided to just leave the Kestrel as my flatland, speed-demon bike and use the Madone in the hills. I actually do use the 53/11 and 52/11 quite often. On my training rides, there are some long, flat, wind-aided, no stop light/sign runs when I can really let it loose. Those of you who are familiar with the winds, terrain, and lack of stop lights in the hinterlands of the Antelope Valley will understand. You can really eat up the miles ... if you're not fighting the wind. Funny in that I don't use the 53/11 on the downhills. I'm too much of a wimp to get much over 35 on the downhill curves and seem to constantly hover my hands over the brakes to keep the speed to a manageable level.

Just picked up the Kestrel from the bike shop last night. Went in for a pro fitting, and we ended up putting on a new stem, (10mm longer). The tech was aghast that the bike was built "dry" and wanted to have their shop lube the bolts properly and check everything over. Looks like they tweaked the truing of the wheels and adjusted everything. On the trainer during the fit, he said it wasn't shifting properly. Got home too late to ride, so I'm looking forward to tomorrow and Saturday. We'll see what this puppy can really do.

Thanks again for the help and advice. Good group of folk here.

The other year I ordered the Madone with a triple (50/39/30 and 12-27). The bike shop really tried to steer me to a compact, but I wanted a triple. My money ... so I got what I wanted. I didn't then, nor do now, buy his argument about "too much overlap".

IMO the industry has a bloody stupid attitude to road triples... prolly because if you have a triple with a close-ratio cassette (unobtainable) you have a gear for every occasion - which would eliminate a whole mess of sales.

I ordered the Madone with a triple (50/39/30 and 12-27). The bike shop really tried to steer me to a compact, but I wanted a triple. My money ... so I got what I wanted. I didn't then, nor do now, buy his argument about "too much overlap". I changed the 50 to a 52 easy enough and dropped in an Ultegra 11-28. That bike is set pretty well for the steeper hills, it's just that the component mix is not the best, (i.e., lightweight). It came with a 105/no-name mix

A Madone with a no-name mix?? What's wrong with these people?

Btw, there's nothing at all wrong with 105. You might save a couple of grams moving to Ultegra or DA: inconsequential.

A Madone with a no-name mix?? What's wrong with these people?

trying to keep the price point out of the stratosphere..

For 10K$ you can get them fitted out full bells and whistles..

If I were concerned about price, I wouldn't buy a Madone. That would be like fitting a Ferrari with a Fiat gearbox to keep the price down...

Besides, he'll be spending more for the upgrades than he would have up front. "Penny wise, pound foolish."

That Madone was my first road bike purchase since 1972. I know squat about the newer technology because I've been perfectly happy with my Mondia Super and have been out of the market on the newer bikes. The Madone 4.5 is the least expensive bike in the Madone series and every year they put less expensive components to keep at a specific price point. In previous years, the 4.5 was all 105 or a Ultegra/105 mix. The year of this bike, a 2010 model, had Tiagra brakes, which just about every user review stated as a weakness. The OEM crank is a Shimano R-553. Not junk, for sure, but not up to 105 level.

If I were concerned about price, I wouldn't buy a Madone. That would be like fitting a Ferrari with a Fiat gearbox to keep the price down...

Besides, he'll be spending more for the upgrades than he would have up front. "Penny wise, pound foolish."

You buy a Madone because it's a fine riding frame. The parts don't make the ride.

I'd rather have a 6 Series Madone with 105 and Tektro brakes and some decent wheels than a lesser carbon frame with DA.

As a shop mechanic and owner, I hate triples on short chain-stay bikes. Yes, they can be made to work, but most customers can't seem to wrap their brains around the idea that no, they don't have 30 usable gears! Yes, that noise is normal when you cross-chain a triple on a bike even Shimano says is at the limit concerning chain-stay length. It's a compromise, and people who spend big bucks don't like to hear that there are compromises involved! LOL