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Replacing an entire Stock crank set (Truvativ to shimano)
#1
Hello folks I am new to this forum so please go easy with me lol

just a quick question, I will try and keep it as simple as possible

I want to replace my entire stock crankset on my Carrera Fury mountain bike. At the moment it has a Truvativ crankset but I want to replace the lot with a Shimano Deore Hollowtech.

What I need to know is will I come across any problems? will I need to replace or adjust my front SRAM X7 Derailleur, (my shifters are SRAM SX5) will I need to replace the chain or rear cassette or anything else?

Cheers folks any tips much appreciated
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#2
If you are going to the expense and trouble of replacing the crankset, spend a little bit more and do the cassette and chain at the same time.

Most like the derailleurs will need a little tweak.
Nigel
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#3
Hi thanks for your reply

so is it absolutely essential that I replace the chain and rear cassette then? This is why I originally asked the question, I don’t want complications and things not being compatible etc.

Yes I would love to get a Shimano Deore xt crankset but that is well out of my budget so I will be sticking with the Deore

cheers
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#4
How worn is the chain and cassette?

If they are nearly new, you should be fine. On the other hand if they are worn, you should replace them as well, otherwise the new chain rings will quickly wear to match the wear of the old chain.

It's worth getting hold of a chain wear checker, something like this: http://www.chainreactioncycles.com/Models.aspx?ModelID=5784&utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom, checking the chain regularly and replacing the chain as soon as it is worn. This will make the chain rings and sprockets, which are far more expensive to replace, last longer.
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#5
Hi thanks for your relpy
as far as I can tell the chain and cassette are fine, the gears shift perfectly. I should say I have done no more than 300 miles on this bike since new, very light use, no off roading only commuting. Saying that though, for what its worth I will probably invest in that chain wear indicator to be on the safe side.

I only want to replace the complete crankset for upgrade reasons. My friend has a Deore Hollowtech on his mtb and its as light as a feather and seems very well built!

If I did need to change the chain or cassette should I go the shimano route or should I stick to the same make as the stock chain and cassette or dont it make much difference?

Really appreciate any tips and help with this one :-)
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#6
Before you rush out and buy a new crank set, you might want to check that the Deore Hollowtech is actually that much better than the one you have.

Truvativ is part of SRAM and they make some good stuff: http://www.sram.com/truvativ/component/cranksets

Also bear in mind that functionally and operationally there isn't much difference between crank sets with the possible exception of some of the very cheap/poor quality no-name stuff. The main difference is weight reduction, but the truth is, you won't notice 100 or 200 grams difference on a whole bike - if you ride off road in wet conditions, the mud on the bike will weigh more than that. Smile

If you want an exceptionally light bike, everything has to be light, frame, wheels, tyres etc. saving weight on one or two components won't make much odds. You really have to start with a light frame and build a bike, choosing all the components with weight in mind, or buy a whole bike that is light to start with.

It's worth noting that bicycle weight, makes less difference on the flat and than on climbs and even then it doesn't make that much. I doubt most people would notice 1 or 2 kilos (2 or 4 pounds) either way in real world use. In addition, some really lightweight, expensive components are often less robust and less durable than some of the less expensive and slightly heavier ones, fine if your a pro and you don't pay for your own tyres, chains, sprockets, mechs etc., not so good if you want a reliable commuter, long distance tourer or a robust MTB.

Here's a couple of articles you may find interesting:
http://www.smartcycles.com/bike_weight.htm
http://www.bmj.com/content/341/bmj.c6801.full
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#7
Well, if you want to upgrade for the sake of upgrading you have to get something really better than the current state. Otherwise the hassle of sourcing parts, comparing prices, worrying about compatibility, replacing, etc. makes no sense. On my road bike I ride Shimano 105 and while I would be able to buy a new Ultegra the difference in functionality, weight etc. is not worth neither the money nor the work. It also makes no sense to mix stuff that is two or three levels apart. I would either stick to what you have or think if the frame is really worth an upgrade to X9 or X0 or Shimano XT / XTR. Then you would do a real upgrade. X5 to Deore is more like a sidegrade... You have low(ish) end SRAM components on your bike. It makes no sense to swap it for another low(ish) end Shimano product (at least on road components there is almost no difference performance wise except that SRAM groups are usually really light).
---
Edit: And do replace chain and cassette, otherwise the chain rings will wear much faster and those are expensive to replace (much more expensive than chain and cassette).
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#8
In my experience, the difference in the operation and functionality between different component levels is far smaller than the manufacturers and marketing men would have you believe.

I recently upgraded my MTB mechs and shifters from Deore LX to Deore XT. To be perfectly honest this was mainly for looks and a miniscule weight saving. I cannot feel any improvement in shifting performance.

I have 3 bicylces, one with 20 year old Deore DX thumb shifters and mechs which work absolutely fine. One with new XT shifters and mechs, which also work well enough, and my "shopping bike" with a Shimano Tourney mech, something like this: http://www.disraeligears.co.uk/Site/Shimano_Tourney_derailleur_%28TY10_GS%29.html. It's all steel and weighs a ton and is generally left, like the rest of the bike, covered in oil and road grime, but it probably has the best, lightest shift action of my 3 bikes - go figure. Smile
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#9
Thanks for all the input here folks its been an interesting read.

I did forget to mention in my original post that one of the reasons I was thinking of replacing my crankset was simply because the bottom bracket to the Truvativ is making an awful cracking noise as I pedal, I originally thought it was my pedals but this was not the case.

I just thought it would have made more sense to replace the lot with an Shimano hollowtech.

The Truvativ bottom backet alone is about £30 so I believe, so for an extra £30 I can get a deore set.

Would really love the XT set but its about £140/150 must be I huge difference in quality for the difference in price I should imagine?

Thanks again for all the help guys :-)
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#10
Before you replace it, just check that the cups are tightened properly and that crank arms are fitted correctly.

You might also want to look at this: http://www.mountainbikerides.co.uk/index.php?option=com_content&view=article&catid=24:drivechain&id=35:shimano-hollowtech-ii-bottom-bracket-bearing-replacement&Itemid=9

Hollowtech/external type bottom brackets use a standard size industrial bearing and you can buy these direct from a bearing wholesaler for a lot less than replacement cups, provided your willing to mess about removing the old ones and fitting the new ones.

http://www.akbearings.co.uk/product.asp?strParents=&CAT_ID=104&P_ID=1056

http://shop.marksman-ind.com/6805-2rs-sealed-ball-bearing-25x37x7mm-1418-p.asp
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#11
Oh, mystery BB noises... are you sure it is the BB? There are so many things that rattle and click on a bike. On my road bike one source is the saddle (Fizik)...

On the performance differences: Tour-magazin (German road cycling rag) made a nice experiment some years ago with road components. Dark room, identical bikes on trainers, different groups. While differences could be of course measured in the lab, the functional difference between different groups could hardly be felt by the testers. (They did not test the really low end stuff, I know that at least the 2009 Sora levers are... crap, they feel unsafe). I guess that this will hold true in general for MTB components, too.
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#12
yes i am 99.99% sure its the bottom bracket. i here this horrible cracking more when i am going up hill and more pressure is on the crank, at first i thought it was my pedals, i can feel the vibration coming out the pedals as i pedals....anyway, i have replaced the stock pedals with DMR V8's but the noise is still there Undecided
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