Is shifting under load bad?

jojoma said:

I just started shifting while out of the saddle, which really helps when taking off from stop lights. But I make sure to ease up on the load to complete the shift. I was wondering if it's okay to shift while hammering away. I have done it accidentally and it doesn't sound like my drivetrain likes it so much. I have 105 from year 2006, so I might need a better group to be able to shift under load.

Thanks

Not really. Depending on your drivetrain geometry, some shifts may be more difficult to complete under a load. Over time, shifting under heavy load will accelerate wear a bit, but the fact is that the amount of shifting done under large loads is likely very small.

Alienator is right, it will wear the gears a little faster but it is made to be able to shift under load especially while climbing a hill, otherwise if you ease up to shift - you would lose momentum.

Fortunately with modern drive train designs, the choice is up to the individual. Yes, wear would increase somewhat if you do it all the time but I am not sure the predominant wear would be chain stretch or some other parameter we don't regularly measure. Yet, losing momentum on a climb can be just as painful.

jojoma said:

I just started shifting while out of the saddle, which really helps when taking off from stop lights. But I make sure to ease up on the load to complete the shift. I was wondering if it's okay to shift while hammering away. I have done it accidentally and it doesn't sound like my drivetrain likes it so much. I have 105 from year 2006, so I might need a better group to be able to shift under load.

I've said this innumerable times -- Campagnolo shifters CAN shift under load with NO PROBLEMS ... downshifting with Shimano's shifters clearly remains problematic, even with the current generation (I presume you have 10-speed, 105 5600 shifters ... which are now considered to be almost-as-good-as-if-not-equal-to the Ultegra 6600 shifters, BTW).

FWIW. After several years of off-and-on-again fiddling with Shimano's STI shifters (alternating the bike's configuration with downtube shifters), I finally/(accidentally?!?) discerned (many years ago) that I could downshift smoothly when the drivetrain was under load (going UPhill) with Campagnolo ERGO shifters regardless of the incline ... I was sold because it meant that I no longer needed to downshift BEFORE the incline to whichever larger cog I wanted to end up with at the end of the particular slope -- the ONLY limitation I have found is not having another gear to downshift to!

I've never had problems shifting under load with shimano either upshifting for sprints or downshifting for climbs. I do club rides and sometimes try to break from the group on steep up hills with 100% efforts with serveral shifts no problems. It always goes into the gear that I want, and it does it fairly quickly. I never downshift before the incline.

The only thing I'm concern about is breaking a tooth on the cog while shifting. I did break a tooth once on my old campagnolo victory equiped bike, and it wasn't even under 100% effort because I had to take may hand off the handlebar to shift from the tube.

On my Shimano Ultegra group I don't go out of the way to shift under load, but I agree with the posts above that it is not a problem. However, when I climbing hard I do find that just a slight ease off when shifting down gets it into gear quicker. Not enough to lose momentum, but enough to get t to slot in fast.