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Discussion Starter #1
Ok. i bought a Giant Fathom. Almost one year. I need a new crank, skipping teeth under pressure. I'm 5'7" and 227 pounds, strong legs. I have a 10 speed and i need a 12 speed. I ride in the 10th gear 80% of the time. My first year of riding and only down once.

My question is? What crank and chain? Do I change over to a 12 speed? I'm a BMW tech and i'm pretty sure I can do the build. I know nothing about parts. I need a crank with strong torque, I assume! What would you recommend me do? I can not buy a new bike. I can put about $600 into it and tools $100. I ride 3 to 4 times a week on path and off and through water and rocks. I like a stiff ride!!

Tires to buy would be nice. i live in the desert, lots of thorns. TY
 

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I doubt you need a new crank, the crank arms and chain ring are most likely fine.

When you said you spend 80% of your time in 10th gear, do you mean the smallest cog in the chain ring or the biggest? If your in the smallest, a new cassette wont have any smaller cogs, just bigger ones for easier pedaling you hills and such.

*Edit

Is your Fathom a 2x10? With a front derailure and a rear?
 

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Discussion Starter #3
It's a 1 x10. Rear only. Smallest cog, I ride in. Why is it slipping? The bike shop had it 3 times, no fix. They replaced the chain. Said it was at 50%. I need more out of the bike when pedaling. So, it's not the gears. So, when at a stop and i'm in the upper gears ready to roll it slips. I'm new so I might not be that good with parts right now.
 

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A bigger chainring. I don't think having 12 gears to going to make a difference unless you are doing a lot of climbing. A new 10 speed cassette would probably be in order, hell, while your at it, give it a new chain also. so new chainring, new cassette and chain.
 

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I don’t know why it’s slipping you didn’t say anything about that until now.

Okay so on your cassette you most likely have a 11 tooth cog for the smallest gear. That’s as small as you can go without upgrading the wheel and cassette. Even then you go from a 11 tooth to a 10 tooth. So not a wise investment. If you’re ridding in the smallest cog and running out of gearing, then going to a bigger front chainring will give you more top end. Going to a 12 speed setup will get you more range from top end to the bottom end. But your top end will be the same.

Now, let’s back this up here. What gear is slipping and when?

Take the rear wheel off, check the cassette and make sure it’s tightend down to the hub.
 

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The Chain ring makes sense! what size?
So they replaced the cassette, nothing. Tried a hub, nothing.
It happens when I start out, 9th or 10th gear, standing up pedaling about the 4 th pedal it skips
 

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The Chain ring makes sense! what size?
So they replaced the cassette, nothing. Tried a hub, nothing.
It happens when I start out, 9th or 10th gear, standing up pedaling about the 4 th pedal it skips
Too much grease or the wrong type of grease on engagement pawls in hub will do this. Springs can't overcome "stickyness" of grease. Easy and free to check, it's worth a shot. Use Slick Honey or equivalent.
 

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The Chain ring makes sense! what size?
So they replaced the cassette, nothing. Tried a hub, nothing.
It happens when I start out, 9th or 10th gear, standing up pedaling about the 4 th pedal it skips
As a BMW mechanic, if someone told you their car was stalling when trying to go from a dead stop in 3rd or 4th gear, what would you tell them? Likely to try accelerating from 1st gear. Same with a bike, from a dead stop put the bike in a lower gear, like 6 or 7. Then as you get your speed up drop it into a higher gear.

If you’re thinking the bigger chain ring is going to stop the skipping issue, you’d be wrong. All it will do is give you more top end speed, but it will take more torque and power to get there.

My guess, and it’s only a guess, is that the derailure is loosing tension on the chain. Because your stressing the system and then it bounces and causes a skip. But again starting out in a lower gear should fix the issue anyways.
 

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+1 for checking the pawls!
 
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