I have a trek 820 mtb that is my only rider accept for my bmx collection from the 80s. My question is when im on a steep hill i have to go to to 1 on my shimano thumbshifters in the rear. The front is usually on 2 on a triple crank set. The rear is a 7. My question is the number 1 seems like im spinning like mad and im not going anywhere and the number 2 seems like a huge jump in cogs and i cant move. I dont know th teeth count yet on these but the jump feels huge to me. For the most part my bike is stock accept for different tires, platfroms pedals and a computer on teh bars. Would any of you casettes under these conditiosn are just tough it out until i can make it up the hard hills in a bigger gear? Mind you im carrying 330 lbs. I think the bike is a bit short for me too at a 18 inch but what can you do? Ive had it 4 years and have put about a 1000 miles on the bike. Ive got the seat raised up as high as it can safely go...When i hhit under 300 im buying a road bike and this will be my play bike or..i might triy to single speed it. Thanks in advance for the help.
Bill Kapaun
06-12-08, 02:36 PM
Front are called chain rings
Rear are called cogs
When shifting the front, you typically have to shift the rear ALSO.
Go to this link and plug in your numbers.
http://sheldonbrown.com/gears/
Look at the chart and you can see where the gear ranges overlap.
Don't worry so much about what the numbers mean. Just look at the ranges that they are similar.
You also want to avoid the extremes like 1-7 or 3-1. The chain runs at too severe of an angle and wears parts prematurely. (Just eyeball it and you'll see what I mean.)
Small ring with the larger cogs
Middle ring with the middle cogs
Large ring with the smaller cogs.
freeagent1970
06-12-08, 02:42 PM
Thanks for the help! I dont run the numbers at extreme angles. This hill im talking about its usually 2/1 and 2/2 seems to much for this hill.
deraltekluge
06-12-08, 05:15 PM
Count the teeth on the sprockets and see what you really have. Sheldon Brown's Gear Calculator (http://www.sheldonbrown.com/gears/) shows quite a variety of "standard" 7-speed cassettes, and with some of them, the jump between 1 and 2 is truly huge. Find out what you have, and use the Gear Calculator to show you what the ratios are for all of your gears. There's almost certainly a lot of overlap in the ratios available using the different front gears. You might be able to find a combination using the small chain ring that falls in between the 2-1 and 2-2 gearings.
I ran one set of numbers for an extreme case, and saw three different gears using the small chain ring (1-2, 1-3, and 1-4) that fell between 2-1 and 2-2 in over-all gear ratios.
Wogsterca
06-12-08, 05:27 PM
I have a trek 820 mtb that is my only rider accept for my bmx collection from the 80s. My question is when im on a steep hill i have to go to to 1 on my shimano thumbshifters in the rear. The front is usually on 2 on a triple crank set. The rear is a 7. My question is the number 1 seems like im spinning like mad and im not going anywhere and the number 2 seems like a huge jump in cogs and i cant move. I dont know th teeth count yet on these but the jump feels huge to me. For the most part my bike is stock accept for different tires, platfroms pedals and a computer on teh bars. Would any of you casettes under these conditiosn are just tough it out until i can make it up the hard hills in a bigger gear? Mind you im carrying 330 lbs. I think the bike is a bit short for me too at a 18 inch but what can you do? Ive had it 4 years and have put about a 1000 miles on the bike. Ive got the seat raised up as high as it can safely go...When i hhit under 300 im buying a road bike and this will be my play bike or..i might triy to single speed it. Thanks in advance for the help.
The magic of gears, there are really 3 ranges of gears with a triple, the small ring (often labeled 1) is a low range of gears, intended for going up hills, it's often called the granny gear. The middle ring (often labeled 2) is intended for flat ground, can be okay for slight inclines and declines, the big ring (often labeled 3) is intended for going down hill. The actual gears do overlap some, and this is a general rule, it's not written in steel or even aluminum. :D
There are two things that become a concern though, with inclines, the steepness of the incline, and the total weight your trying to move up it, at 330lbs gravity is not your friend :giver: Although gravity gets pretty friending going downhill :speedy:
The other solution for hills, if they are steep, but short, is to raise off the saddle and tough over them, the problem is, that at your weight, guys usually have a lot of torque, enough torque that standing to power over hills, can break something, cranks and bottom brackets, especially lower end ones, are most susceptible, considering the price of the 820 these are likely lower end parts, I wouldn't recommend it.