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Im new. Need help.
#1
I have an entry level MB Diamondback Sorrento from 2011 and I need a new crank set and FD. Currently, my bike has a MTB 24/32/42t and my BB width is not specified. I'm looking for a replacement crank set without breaking the bank. If I have to get a new chain or BB then so be it. But I'm trying to avoid a front end rebuild.

For reference, my back cassette is a 7-speed 14-28.

Can I change chainring sizes without getting a new BB? And how do I know it will be compatible with my frame and rear cassette? Insight would be much appreciated.
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#2
You can measure the BB shell width (in mm) yourself with a ruler. If the specs for the bike list the specific crank just look up the length of spindle that fits it. Your replacement should take the same spindle length. If you replace BB and cranks you need to match "chainline" (Google it).
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#3
Please also note, that you likely have a freewheel, not a cassette.

Measure your chain for stretch; the only tool you need is a ruler. There are guidelines on the web, each person has their own, I am rather conservative: if there a 1/16" of stretch, replace the chain, if there is an 1/8" of stretch, replace both the chain and the freewheel/cassette.
Nigel
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#4
If the chain is not "stretched" but you put on a crank with a bigger large chainwheel you may have to replace the chain anyway. Look up "sizing bike chain."
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#5
Could someone help me out? I recently purchased a new single speed bike sprocket. I put it on my bike and I had to make the chain smaller. Anyways I got everything put together and its as if the bike doesn't have enough tension when you pedal. like when you pedal it feels like the chain isn't even on. the cranks spin almost to freely.
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#6
(02-14-2015, 02:04 AM)jaydenthecreator Wrote:  Could someone help me out? I recently purchased a new single speed bike sprocket. I put it on my bike and I had to make the chain smaller. Anyways I got everything put together and its as if the bike doesn't have enough tension when you pedal. like when you pedal it feels like the chain isn't even on. the cranks spin almost to freely.

Lift the back of the bike up in the air and turn the cranks. When the cranks turn, does it make the back wheel spin or does the rear sprocket just spin without turning the wheel? And just to confirm, did you put on a single speed freewheel (where you can coast) or a fixed cog (where if you pedal backwards, the wheel turns backwards)?

[Also, it's best to start a new thread when you have a question, don't just add on to an old thread. And you don't need to post the same question multiple times. It won't get you a faster response and it's just going to annoy people. FYI]
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