[godaisan]

I'm new to biking and I decided earlier this year to get a 2005 Rocky Mountain Vapor as a beginner's bike.

I noticed when the chain is on the largest chainring at the front and the smallest at the back, under heavy pedalling, the chain rubs against the front derailleur. The Local bike shop here adjusted the bike and said there is nothing else that can be done.

The Crankset the bike came with is the RPM CY2F.
Would upgrading the Crankset help? (I could have sworn the Vapor came with a Shimano crankset)

Johann

 

[GearHead]

If there is no rubbing when in this gear combo under light pedalling but rubbing occurs under hard pedalling then it is due to the crank flexing too much. Cheap cranks do this, flex too much. Your bike shop is correct, a new crank will fix this. Anything Shimano Deore and up will be stiff enough so that not to flex and cause rubbing (unless you are a super clyde).

 

[godaisan]

Thanks for the info Gearhead.
I guess when you go for the entry level bikes, the components may not always be the highest quality.

Time to do some price comparisons on cranksets. Any recommendations on where to shop for components?

Johann

 

[Mervyn_b]

I'm new to biking and I decided earlier this year to get a 2005 Rocky Mountain Vapor as a beginner's bike.

I noticed when the chain is on the largest chainring at the front and the smallest at the back, under heavy pedalling, the chain rubs against the front derailleur. The Local bike shop here adjusted the bike and said there is nothing else that can be done.

The Crankset the bike came with is the RPM CY2F.
Would upgrading the Crankset help? (I could have sworn the Vapor came with a Shimano crankset)

Johann

Hmmm, just a guess, try rotating the front der a lil bit just to add some clearance - it's boring to have chain rubbing at this gear combo, considering there's no cross-chaining.

 

[GearHead]

Hmmm, just a guess, try rotating the front der a lil bit just to add some clearance - it's boring to have chain rubbing at this gear combo, considering there's no cross-chaining.

I have tried this approach on similar cheaper cranks with bad results. If I was to rotate the back of the derailleur out enough so there was no rubbing then it was out too far to shift from the middle to the small chainring. Also, even back off the high limit screw and chancing the possibilty of overshifting the large chainring wouldn'e do it either. Flexing cranks is one of my pet peaves. I hate working on stuff that just can't operate correctly no matter what you do.

 

[Mervyn_b]

I have tried this approach on similar cheaper cranks with bad results. If I was to rotate the back of the derailleur out enough so there was no rubbing then it was out too far to shift from the middle to the small chainring. Also, even back off the high limit screw and chancing the possibilty of overshifting the large chainring wouldn'e do it either. Flexing cranks is one of my pet peaves. I hate working on stuff that just can't operate correctly no matter what you do.

Got that right GearHead, you're absolutely right. Best solution : Looks like it's a must to get those cranks upgraded - that surely won't be a waste of money for sure. At least a Deore crankset would be fine for me. That's my opinion at least.

 

[godaisan]

Thanks for all the info.

Would you recommend purchasing a new crankset online? Or purchase it at the LBS?

 

[GearHead]

That really depends on your LBS and if you plan on installing the crank yourself. If you have a good LBS who is willing to share their knowledge and gives good prices on components, I would definitley buy from them. I am personally a LBS supporter and I am willing to pay a small amount more at the LBS (10%-20% depending on the price) due to the convience, ease of ordering, and possible warranty claims. Usually my LBS will match any mail order price for me after considering shipping and such, only exceptions being close out deals.

If you plan on having the LBS install the crank, you probably should buy it from there. The wrenches typically don't like installing components not bought there or may charge you more for the installation.

If you LBS are a bunch of idiots (which seems to be the more common case) and you plan on installing the crank yourself, mail order is the way to go. Easiest way to get the cheapest parts.

 

[Mervyn_b]

Thanks for all the info.

Would you recommend purchasing a new crankset online? Or purchase it at the LBS?

I'd suggest you try fitting it yourself, start learning how to do things yourself. I agree with GearHead again, most workers at the LBS's are just wanna-be mechs. As long as you follow the instructions and maybe get hold of some of the best books available (Zinn comes to mind) and follow their instructions, and tools maybe, doing it yourself is the best way to go. An other thing, if you're going to upgrade the crankset, try upgrading the Bottom Bracket too (my opinion is don't go cheap on this one, get the best one you can afford and be sure it's got the same interface as the new cranket (ISIS, Octalink etc.) and size. Again, my opinion...

 

[Fluffbomb]

Avoid ISIS

Hopefully the new SKF ISIS bottom brackets will be good but at the moment avoid ISIS bottom brakets unless you fancy replacing them regularly.

Fluff