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Trek 1.2 crank arm replacement

by theWHISK
Wed, Jul 22, 2020 16:21
3

Hi,
Recently got my first road bike on ebay, a trek 1.2 alpha. I think it is probably 2010 model. It is great for the most part but I have found the crank arm has threaded and had my pedal come loose on me, would anyone be able to point me in the right direction for a replacement? I'm not sure what exactly I need to look out for in purchasing a new one but I'm thinking it will just be the crank arm itself I need to replace. The existing ones are 'fsa vero' but I'm not confident enough to order the first set I see online. Do they come in various sizes or dimensions or will any set of fsa vero crank arms fit? Is it worth looking at other options? Is it worth replacing anything else whilst I'm down there, as I'm pretty sure it was all original parts when I got it (I've already changed all the cables, pads and regreased the head tube, it's just the bottom bracket area I haven't looked at yet.)?
Thanks

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3 comments

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davidgray968 | 3 years ago
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As pedals and cranks are separate items I can only assume from what you have said is that the pedal has come loose and not the crank arm. Normally pedals are either locked on via a pedal spanner which fits the hexagon part of the pedal spindle closest to the crank arm. If you can't see a hexagon shape closest to the crank arm look on the inside there will be an allen key shaped hole instead.

If the left hand crank arm is loose then you need to tighten the 2 bolts which hold it onto the crank arm, tighten evenly.

Check online for all training videos - Park Tools do very good ones.

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Welsh boy replied to davidgray968 | 3 years ago
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Firstly, having had a quick look the FSA Vero left hand crank doesnt appear to have two bolts holding it to anything so i am not sure what davidgray means by his post.  If the crank has come loose on the spindle (the bit which goes through the frame onto which the cranks fit) there will be a single bolt holding it tight onto a tapered square fitting, this will usually be an 8mm hex key to tighten the bolt holding in on up.  If the thread into which the pedal fits has stripped then you will need to replace the crank (yes, I know you can get them repaired but the cost of a repair will exceed the cost of a replacement).  However, you will need some special tools to remove the crank from the spindle so I suggest a quick trip to your local bike shop to get the replacement sorted out and ask them to show you what they are doing so you will know for next time.  Cranks also come in a variety of lengths, yours will probably be marked near the pedal fitting and will probably be 165mm, 170mm or 175mm which is the length of the crank measured from the contre of the pedal thread to the centre of the axle fitting, you will need to match the new to what you already have on the bike. If you are taking the left pedal off it has a left hand thread so you need to turn it clockwise to remove it.  Replacement cranks and chainrings will probably cost you from about £60 plus labour for the work the bike shop has to do but if you are lucky you may get away with just a new crank which will probably cost around £20

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theWHISK replied to Welsh boy | 3 years ago
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Thanks for getting back to me guys.

To clarify, yes, the thread in the right hand crank arm that the pedal screws into has been stripped. So obvioulsy then I have to also consider the chain rings as well as it has five arms that connect between the two rings. 
It is similar to this but it doesn't look exactly the same, do you think the product here will be interchangable with what is on my bike currently? 

The crank currently on my bike more specifically says 'powerdrive' on it but a quick google of 'fsa vero powerdrive' doesn't really return much specific. 

If I can get away with just changing the cranks that would be great. 
But I am also wondering if it would be worth changing the chainring, bottom bracket and/or spindle whilst I am at it. As it is potentially a 10yr old bike and I do intend to get a few years out of it.
-Is it likely to make much difference or would I be fine just giving it a clean and regreasing the bottom bracket? 

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