Mountain Bike Reviews Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
Hey all, I just got a Trek 820 bike and I'm breaking it in, but I do have one problem. I don't know when to shift gears for the front derailleur and when to shift in the back. I'm getting the hang of when to shift, I just don't know why I should use one derailleur set over the other. Is it simply a preference or is there method behind this madness?

Thanks,
Jim
 

·
Registered
Joined
·
309 Posts
There is a method to the seeming madness (though I haven't figured it out yet), but you have to understand that on most drivetrains there is so much overlap between gear ratios that many gears are redundant. The XTR Dual Control on my ride doesn't have a display to tell you which gear you're in, so I usually hang in the middle chain ring for most stuff, the big ring when I'm on a downhill/flat and looking for speed, and the Granny gear only if I really REALLY need it (luckily haven't had that happen yet, but it's coming). The rear cog is used to make sure I'm able to keep my cadence and output level comfortable, at least to my way of thinking. I'm sure someone here's gonna give you a better answer, but that's mine, and it seems to work for me. :thumbsup:

Best of luck!

Ross
 

·
Registered
Joined
·
115 Posts
As was said above, I too am usually on the middle chain ring the majority of the time. It seems like I stay on the same 3 or 4 cogs on the rear whenever I ride. I very rarely use the small chain ring though. I like to use the large ring on flats and downhills. I had to use it the other day to keep from getting ran over while riding on the road for a short stint between two trails.

Kris
 

·
Registered
Joined
·
159 Posts
I use both the middle and big ring for flat depending on how fast i want to go. The small ring for hills and the on downhill the big one. When it gets to easy/hard to pedal switch cogs if you keep shifting up or down alot switch chainrings and the swith the cogs to match the last gear you were in. I don't know if that made sense but hopefully it will help you.

Don't cross your chain.
if you are in the middle ring use the middle cogs
the big ring the smaller cogs
the small ring the bigger cogs
REMEMBER
don't do big(chainring) & big(cog)
or small & small
 

·
local trails rider
Joined
·
12,300 Posts
giant alameda rider said:
Don't cross your chain.
if you are in the middle ring use the middle cogs
the big ring the smaller cogs
the small ring the bigger cogs
On trails I am usually on the middle ring and middle cogs.
Big ring mainly gets used on the road (transitions from one piece of trail to the next).
Small ring only gets used on the few climbs that are long and steep enough to kill me whatever I do...
 

·
ravingbikefiend
Joined
·
2,322 Posts
More on what alameda said...

With a multiple chainring there is always some gear overlap and the issue of chain deflection arises...this is when you are running on the top chainring and lowest (largest ) rear cog or running the smallest front and highest (smallest) rear cog.

What happens here is that the chain runs at a high offset and causes undue wear on the chain , chainrings, rear cogs, and sometimes the front deraileur. Because of the existing gear overlap you have, you should never have to do this.

The straighter the chainline stays, the more efficient you will be and this practice will prolong the life of your driveline and make for more efficient use of power.

A good rule is to use your 3-4 lowest (largest cogs) gears with your smallest front ring, use all the rear cogs when you run the middle chainring, and limit yourself to using the 3-4 smallest rear cogs when you are running off the largest (top) chainring.

There is enough gear overlap in a typical 27 speed that the number of unique gears is really only 15-17.

As for when to shift...

I generally maintain a fairly high cadence (about 120) when I'm riding and adjust my gearing so that I can comfortably maintain that cadence. If the workload increases I downshift and if the workload decreases I upshift.

I do prefer to stand and power my way up most hills so will run in a higher gear for this as to prevent myself from spinning out.
 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top