7bmwm3gtr

I see it all the time. Today I rode behind a group and they were crosschaining. Most of them had 50 or 53 and a double or compact crank.. But their chains were pretty crossed and they were all doing it.

So I'm now curious about crosschaining with a triple crank. I have 50/39/30 and 26-12 in the front and rear respectively. When I use my 50, i stay in the 9th, 8th, 7th, 6th, and 5th gears. I never go lower than that.

However I want to know, if it's safe to be in my 39 while riding in the first 6 gears, this includes the 26 teeth in the cassette.

Please help me out, because i really hate climbing in my 30, and i'm a much more optimal climber with the 39.

Thanks.

Beaker

Two things come to mind. The first is that in your 39 you should be fine using your biggest gears on the back (including your 26). The second is if you're using a 9sp setup, then I believe they're less prone to cross chaining than 10sp.

7bmwm3gtr

Thanks! It was such a concern, that i didn't really use my 39 in the San Bruno Mountain Race, and now i regret that because it really does contribute to a better and faster climb!

dorkypants

Cross-chaining used to be more of a problem with older drivetrains, whose chains lacked as much lateral flexibility as 9- and 10-speed chains have (it's been too long for me to remember if 8- and 7-speed chains were also sufficiently flexible). In such cases, you ran the risk of unwanted shifts when cross-chained.

There can still be conditions even with 9- and 10-speed drivetrains where the combination of gear sizes, chain length and rear-derailleur cage length can cause a total jam if you combine large chainring with the larger rear cogs. Conversely (but with much less disastrous consequences), a small-small combination can cause a very slack chain, and possibly interference between the backward-moving bottom stretch (no pun intended) of chain and the forward-moving section of chain passing over the upper pulley on the derailleur cage.

Banzai

A truly Fredly thing to obsess over.

As long as everything is working, just relax and ride. You have all those gears for a reason.

7bmwm3gtr

Okay here is what i mean:

Here is the position on my 26 (First Gear).


Then Here it is on my 5th.

Banzai

Get a planetary geared hub.

Then maybe you can chill out.

Besides, I think internal gears up your Fred-entials substantially. It's like a golden ticket into the club.

7bmwm3gtr

Well i'm basically just curious to know if it will drastically affect the life of the chain.

Also, If it is safe, i would be saving money because i don't want to upgrade to a double crank when i have a 39 already, and in a worst case scenario i can drop to my 30.

Once I get used to the 39 by itself, then i will upgrade to a whole better bike with a 53/39 and a 10 speed, where i will not have to worry about triple cross-chaining.

Of course, this bike will have to be my race bike, (unless my team gives me a bike), due to the limited gearing restrictions that the Junior category has.

knobster

I think you'll be fine on any gear in the 39. The 30 and 50 is where you'll run into problems eventually. Using the 50 with the lower gears (26, 25, etc) will work but usually be a little noisy and will wear the chain a little faster. Same with the 30 and the higher gears. To switch your current setup to a double, all, you'd need is a crank. You can pick those up off ebay pretty cheaply. Take a couple links out of the chain, adjust the limit screws on the FD (maybe raise it if going with a 53) and you're golden.

Beaker

Just don't tell me you climbed that in your 50.....

Barrettscv 

A triple crankset should help you avoid cross-chaining. As others have said, use the 39t chain-ring for most of you riding, and don't worry about cross-chaining on the middle gear. Avoid using the big chain-ring at speeds below 15 mph, don't use the big chain-ring in combination with the 2 cogs closest to the spokes. Avoid using the small chain-ring in combination with the two cogs closest to the chain-stay.

A compact double crank-set is not the solution. Careful shifted is needed to avoid cross-chaining on a compact double. The compact double crank-set requires constant shifting between the chain-rings to avoid cross-chaining.

Michael

ericm979

Shimano recommends not using the smallest and largest cogs when in the middle ring of a triple. When in the large ring, they recommend not to use the largest two cogs, and when in the small ring, the smallest two.

When I had a triple I sometimes used the largest cog and the middle ring. I don't think it wore anything significantly more than normal.

If you wanted to switch to a double you'd need the double crank (unless you have a non integrated crank, i.e. Octalink, in which case you'd need a double BB and to remove the granny ring but you could use the rest of your crankset). And a double front derailleur.


I disagree with Barretscv about cross-chaining doubles vs triples.... there is more cross chaining possible with a triple because the chainrings are farther away from the center of the cluster. For a double (compact or not) Shimano recommends not using the large cog with the big ring and the small cog with the small ring. There are fewer disallowed combinations (2) than with a triple (6).

Barrettscv 

My point concerning the compact double (not all doubles) has everything to do with rider gear selection. Most riders using a compact double and traveling in the 17 to 21 mph range can be found cross chaining. Either they are using the big-big combination or the small-small combination.

The 39t chainring found on most regular doubles and most road triples avoids the need for using the gear combinations that cause cross chaining.

Michael

Grumpy McTrumpy

why do you hate your 30?

7bmwm3gtr

Climbing is too easy, but too slow.

operator

There's a lot of irrelevant info on this thread.

Here's the basic, anytime you run the chain that deviates from perfectly straight you're it's "worse". It's up to the rider to decide when or where to use a chain combo that is near or at max angle. If a chain is cut to the proper length and the drivetrain components are compatible, every gear should be safe to shift into.

DaveSSS 

It's not that complicated. The middle ring on a triple is nearly as far to the right as the big ring on a double - treat it as such. The little ring is not significantly further to the left than the little ring of a double. The big ring is usually 5mm further to the right than the big ring of a double. That means that at least one more cog is off limits.

You can shift into any extreme chainline combination you want, but that does not make it a smart thing to do. Anyone with any brains will get out of the little ring long before getting to the smallest two cogs. I would not use the middle ring with the largest cog for very long or the big ring with the two largest cogs.

simplify

It's dependent also on what your chainline is like. Some cranksets are positioned such that they're more outboard or inboard. In the photo, yours looks to be more outboard, so you can take that into account when deciding what combinations you feel comfortable with. You may also be able to adjust the chainline of your crankset, some are adjustable.

Bottom line, don't obsess about wear on the chain--at least not enough to keep you from using gears that you feel you need. The chain is a very temporary part in your drivetrain, and side-to-side wear isn't going to affect its overall lifespan that much. You should change it out very often anyway, so use it to the best advantage for your riding, monitor its condition and change it often.

grwoolf

I have a compact double and cross chain big to big quite sometimes to avoid dropping to my 34 up front on short climbs. If it's anything longer than a few minutes, I'll drop to my 34. The big to big combo is pretty smooth and quiet. The small to small is kind of noisey, so I don't use that. If cross-chaining wears my drivetrain out quicker, so be it. If I had a triple up front, I'd use whatever gears are available as long as they weren't making a bunch of noise (that just drives me crazy).

Oh, and the best reason to cross chain: Lance does it, so it must be cool. I think it was the TDF individual TT last year where they had a good shot of a cross chain. Of course, his drive train is probably replaced constantly, so no concerns about wear and tear.

crhilton

Doesn't everybody climb in a 50x15 combination?

Mr. Beanz

So your 30 doesn't have a similar gear combo to the 39 combo you use?..as far as gear inches?

DMF 

Using your numbers, there are more allowed combinations (24) with a triple than with a double (18).

Barretscv is 100% correct. While it is possible to cross-chain more severely with a triple, in practice it happens much less often because the 1 and 3 rings are closer (in chainline) to the cogs you use with them.

Btw, where is this "Shimano recommendation" that I've never seen?

njkayaker

Many triples are set up so that the gears that one would cross chain in are duplicated (nearly) elsewhere.

Running a gear chart on your setup might show this.

https://sheldonbrown.com/gears/

"Crosschaining" is clearly a progressive thing. That is, the only situation where crosschaining is zero is when the front/rear gears are in the same plane. For anything else, it's crosschaining to a more or less degree.

I asked in the "mechanics" forum what rules people knew of about avoiding excessive crosschaining and people there yelled at me!

If your crosschaining rule is to avoid using crossing the largest-smallest combinations, it might be somewhat prudent to reduce the times one uses the largest-smallest cogs from the middle ring.

DMF 

Yelled at you for what?

You're right about the "progressive" nature of cross-chaining. The greater the angle the more you should avoid it. No one disagrees about that.

Where there is vehement 'debate' is how cross-chaining somehow justifies a compact over a triple or vice versa. IMO, cross-chaining isn't a real issue in that debate, but there are urban myths and people that need to justify their choice. The result is a bunch of mis-information, or information taken way out of context.

RacerOne

I don't seem to have a problem using the middle large combo on my triple, but middle small is a no-no.