DTSCDS

Okay, so this is probably a very basic question but here goes...
When heading uphill and needing to shift between the front rings--how do you keep from losing all momentum as you finish your front ring shift, but are now in much to low a gear on the back and are spinning like a madman? Is it possible to shift both at the same time so you can hit the next gear ratio down from where you started pre-shift? (If that is the right wording)

flip18436572

I only shift one at a time. Unless I go from a 0% incline to 15% incline, I can usually stay on one of my two front drive rings. That being said, if I need to change gear rings, I will push harder and then switch the front to the easier, and then shift the back to the harder, but it only takes a few seconds. I try to keep my cadence around 90, so it doesn't take long for the gear changes.

What is your cadence when you are shifting?

Halthane

Also if you are needing to shift into your smaller ring up front learn to do it before you get all the way down the cassette. ie, when in the middle of the cassette on the big ring, shift to the small ring. There is usually a point in the cassette where the change from big to small ring is about the same, this is where I make my shift.

BikEthan

Generally if you're hitting a steep incline and you're going to want a smaller chain ring you're better off shifting just before you start to ascend. If you're forced to shift while going uphill I usually give it a good push right before hand to get the strain off the drive train. This helps prevent chain suck and other front shifting issues. Then I'll shift into a smaller rear cog as needed.

Ray Dockrey

I run a compact crank and have to do this regularly. I do both at the same time. Very common on compact cranks. There is a thread somewhere that talks about this. One click on the left shifter and three on the right shifter for me. I have gotten pretty good at it and don't think much about it anymore.

DTSCDS

Okay, I think this may prove extremely helpful to me. So, let me asks this: Are you saying that when in the big ring and in a certain gear in the cassette will somewhat 'overlap' with the middle ring in another gear in the cassette. If so, is there some kind of online thingy where I could input my gear/cassette numbers and find where these overlap points are? That way I could know that when I need to downshift from the big ring I need to do it when I get to gear x.

Torrilin

Sheldon Brown's gear calculator is your friend here. It will spit out a nice chart in whatever units you like.

Tom Stormcrowe

And here's that link

https://www.sheldonbrown.com/gears/

DTSCDS

Okay, so once again the Sheldon Brown site is a wealth of information. Now the problem is, how do I interpret the information in the chart? I input my numbers and it came back with a chart with % between cogs. How do I take that info and translate that into "when in ring x and cassette gear y, downshift into ring x and cassette y." I don't expect anyone to take a long time trying to educate me. A website or other source would be fine but the more simple the better. Or, is this just something I am going to have to learn by doing? I am going for a ride tonight in a area where there are a few hills so I will get to try the "downshift the front ring and upshift the rear" approach.
Thanks to everyone for their help

Tom Stormcrowe

You can change the option to MPH in each gear as well, which will give you an idea that you can visualize. Example: In the big ring, small cog, the combination on my bike is 53:13. That gives me 38.7 MPH at 120 RPM, and in the lowest gear I have, it's 4.2MPH at 90 RPM.

deraltekluge

You can get the results in mph or gear inches or other units, showing the over-all ratios for each combination. You can look at the numbers for each gear and see how they overlap and which are equivalent. Here's one I did once upon a time for a mountain bike (22/32/44 chain rings, 11-32 9-speed cassette, 26" tires) in mph at a cadence of 60 (1 revolution of the crank per second).



The figures in the white boxes are the mph for each combination. You could accomplish the same comparison with gear inches if you desire.

Note that the lowest gear using the middle ring is in between 3rd and 4th using the small ring, and the highest gear using the middle ring is in between 6th and 7th using the large ring...so there's about a 2½ gear overlap. That is, changing one gear on the front derailleur is about equivalent to a two or three gear change on the rear.

piper_chuck

Going back to the original question, I use a couple different strategies depending on the situation. To begin with, I usually ride a triple, so a shift on the front ring typically translates to one or maybe two different cogs in the back. This is one of several reasons I ride the triple instead of a compact.

One thing I do regularly is a double shift. I hit the downshift for the front at the same time as I upshift once on the back. Much of the time, this works flawlessly.

Another strategy I've used is to actually do the upshift on the back followed by the downshift on the front. When I do this, I have to grunt it out at a lower cadence for a few seconds.

And yet another is to do the downshift on the front, but instead of spinning like crazy, just freewheel at the same cadence. Then adjust the back as necessary to get it in synch with the cadence.

The thing that seems most important is to get the front ring in the right position before the hill gets steep and you've lost too much momentum.

Wogster

There are three schools of thought, first school is that for a beginner with a triple crank (three gears on the front), the lowest is for uphill, then middle is for flats, and the big is for downhill, the problem is when you have rollers, that is you go up then down then up then down, in which case you can use the clyde cyclists secret weapon, duc.... er momentum. As you get stronger, you will find yourself using the small or granny ring less, and the middle and large rings more. Essentially as you barrel down the hill in the large ring, you slow your pedaling and shift to the smaller ring, shifting up a couple of gears on the back so that your essentially in the same place, you can do this on the flats as well, slow your pedaling slightly as you approach the hill, and then shift both ends while momentum carries you along. As you down shift, ease up on the pedals a little, to make the shift easier.
With a bicycle that is well tuned and mechanically in good shape, you can shift both at once, however if something is slightly worn or off, you can neatly drop the chain between gears on one or even both ends, and that means your walkingm, hopefully not to the ambulance.

The second school of thought, is you mathematically compute in gear inches or some other units all of your gears, and then shift at exactly the right point, by exactly the right amount, to get the next mathematical gear, people will print out little charts and follow them religiously. If you think this is a little anal retentive, I would agree with you. A little less anal version is to make the chart, to figure out where your major front shift points are, in relation to the back, and develop a sequence like 1/1 1/2 1/3 1/4 2/3 2/4 2/5 2/6 3/5 3/6 3/7 3/8 which you follow up or down, depending on need.

Third is to simply avoid the cross chains, when you shift the front you shift the back in the opposite direction by a gear or two, and forget the math.