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Discussion Starter · #1 ·
I want to replace the stock crank on my Madone 5.5 Pro 2008 (Bontrager Race X Lite) with an SRAM Force crankset.
My questions are:
1. Would the SRAM Force crank fit my bike?
2. Will I be able to use the GXP Team BB that comes with the SRAM Force crank?

Thank you for your help!
 

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monkey with flamethrower
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The answer is yes, that will work just fine. The better question you should be asking is why are you replacing your crank with an identical crank. Sram makes all of Bontragers cranks and the only real difference between the X-light and the force is the rings on the X-light are not as nice. That and the decals.
 

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gba said:
I want to replace the stock crank on my Madone 5.5 Pro 2008 (Bontrager Race X Lite) with an SRAM Force crankset.
My questions are:
1. Would the SRAM Force crank fit my bike?
2. Will I be able to use the GXP Team BB that comes with the SRAM Force crank?

Thank you for your help!
Cranks yes, BB no. The 08 Madone line has the pressed bearings already. I am 99% Sure of that. So you just swap cranks.

When the bearings go, your LBS can remove them and press in new ones.
 

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The cranks are a direct swap but you will need the bearing kit for the Sram cranks. I am not sure if they are a Trek only item but I do know that you will need the bearing kit. I am picking up my 6.5 today and had the LBS change the crank to RED, they ordered the bearing kit from Trek. I have the part number at home, not sure if it would be the same but I can post it later if you need it.
 

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Discussion Starter · #6 ·
Thank you all for your replies.

The reason I want to change my crank is that the rings (or maybe the spider - I really don't care) are bent after minimal use - 1200 miles. They probably have been bent since much lower mileage but I haven't noticed.

The reason I consider Sram Force is because I have full Force except for the crank. I might consider Red if there is a difference in performance, because the price difference is not so high (on Ebay).

Rubber Lizard - are you 100% sure that Force and X lite are identical?

endeavorc - If you could post (or send me) the part number I would really appreciate it.
 

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monkey with flamethrower
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I am 100% certain that the Force and Race X-light are the same crank. The only difference is that Sram uses different chainrings and bolts on the Force crankset. The X-light has been a rebadged Sram carbon crank for many years. That may have changed, but the two cranks look nearly identical.
 

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Much cheaper fix

gba said:
The reason I want to change my crank is that the rings (or maybe the spider - I really don't care) are bent after minimal use - 1200 miles.
That is an easy problem to fix, and it doesn't require a new crank: you have to straighten your spiders and/or chain rings. Hold a small screwdriver or other short, pointed object against the seat tube so that the tip just grazes the crank spiders as they pass. If the spiders are bent (most likely problem), you can even them out as follows:

Place the bike on its side with the crank supported on a block of wood at the axle. With another block of wood or a stout dowel placed at the end of the offending spider(s) give it a whack with a hammer. Check for change in alignment. If you got no change, hit it harder next time. Repeat until all the spiders are even. You may need to bend them away from the frame (brace the right crank on the block of wood) or toward the frame (brace the left crank).

Once the spiders are even, check the chain rings with the same technique except put the point of your screwdriver at the teeth of the rings (most likely the big ring only if the spiders are even). Straighten the chain ring by placing a large adjustable wrench over the ring with the jaws adjusted for a slip fit over the ring. Bend gently, and check alignment. Repeat until you've got it right.

Even with the chain rings dead straight, you still will get some deflection due to pedaling forces, but that should greatly improve your situation.
 

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Not so. The Bontrager Race X Lite, made by Truvative, has a carbon arm bonded to an alloy spider. The Sram Force is a one piece carbon arm and spider. They are both "descended" from the Truvative 2 piece crank family (e.g. the Roleur). They both use exactly the same bb/bearings. Truvative called it the Giga X Pipe, Sram the GXP.

So pull the Bontrager and put in the Sram. Use the bearings already seated in the frame.
 

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Descender
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+1 to the above. Those carbon coated alu cranks from Bonty / Truvative come in several hundred grams heavier than the Force also. The 5.2 with the Ultegra SL is a better crank then the Bonty.

The Bonty crank would be the first thing I would change on a newer Trek.

As Richard and others noted the Sram will work fine with the trek BB.
 
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