CRANK ARM and BOTTOM BRACKET question
 

Hello guys, I bought a trek madone and I wanted to make sure that I'm not missing anything.

I've noticed today that where my crank arm connects to the bottom bracket that there are bikes with really large spacers, some with washers... but mine looks like the crank arms slides right onto the frame... I haven't seen a lot of bikes and I've never focused on it but wanted to make sure that it's normal. The crank arm flows perfectly IMO I just wanted to make sure it's normal. Thank you.

http://bikeforums.net/attachment.php...hmentid=312092

I would say the position of your Shimano crank arm is incorrect. It is too close to left side of the frame BB.
Next step is to hold the frame seat tube with your right hand and pull and push on the left crank arm shown with your left hand.
This will reveal if there is any axial play. My guess is...the crank is improperly installed with insufficient spacers on the left side.
Shimano cranks with dual pinch bolts can be attached laterally in multiple positions. It looks by the pic, the arm is actually scraping on the side of the BB.
If you aren't technical, take it to your bike shop to have the crank properly set up. It is a simple matter but you may need another spacer or two...remove the left arm and properly adusted lateral lash.

My BB86 has about 1mm-2mm of the BB shell (?) between the crank arms and the frame. I would follow Campag4life's advice, if not just for piece of mind. Have you "Googled" Trek Madorne Bottom Brackets and checked for pictures?

Madone BB's are set into the frame. You just insert the bearings into the frame. It looks fine to me.

Hmmm. Looking at my wife's 2011 Madone 6 with a BB90, there's about 2 mm between the crank arm and BB shell, but that's with SRAM cranks.

I image googled pics and it does appear there are some madones that have it w/o a spacer/washer or anything and others w/ a red colored washer type.

Are these "really large spacers" perhaps external bearings? E.g.:

http://brimages.bikeboardmedia.netdn...externalbb.jpg

There are both 7 and 8mm wide bearings that will press into the Trek BB90.
I enhanced the pic the OP posted. What I thought were scrape marks on the left crank arm may in fact be grease...or grit.

If shown is proper spacing, its the tightest clearance on the planet. :)

Those technically are called bearing cups. Yes, external bearings reside inside those cups which are on the outside of the BB shell. The Trek BB is completely different. The BB shell is 90mm wide and not 68mm...hence its name BB90. Intent is to have bearings inside the very wide BB shell but pressed in like BB30 or PF30. As to crank spacing, the same long spindle external bearing crank like Ultegra or DA can be used in the Trek 90mm wide BB...only difference is the bearings are pressed into and reside within the BB shell versus on the outside as with an external BB shown.

Is there a detriment to the crank arms being that way w/ the bb? That's my main concern... I do not feel any grinding... I don't feel any friction, the arms spin well for me and I've been thru the cadence band of 50 to 120 without a problem. If it's fine as is I have no issues, I just don't want to have a failure :) Thanks for everybody's insight. BTW if it helps at all I bought it from a person who build it from the madone FRAME, it wasn't purchased stock from Trek or a Trek distributor.

There's just crude in the gap.

Like I said - it's fine. It's how the Madone was designed.

It also was designed like this:
http://bikeforums.net/attachment.php...hmentid=312271

Thank you guys for the help :)

not being real familiar with BB90, if it was my bike, I would expect (like most bikes I've had/worked on) that the crankarms should be equidistant from the stays, when properly installed. This is not hard and fast, but usually works out that way.
So, just to move my confusion forward another notch, I would measure from the inside of each crank arm (could be at the end, using a set of calipers) straight over to the stay. If each side is within 1mm of the other, then I'd prolly call it 'good' and maybe consider the implications of this 'design'. If the difference is 3mm or more, I'd think something was askew...
An email to Trek should give their perspective on proper installation of the BB 90 crankset. Or it might even be online in a tech manual ?

That ^ BB doesn't look like the other one, which protrudes out a little.

I asked you to check for lateral play in my earlier post and you never responded. Sounds as though function is fine. So what Rob said is probably correct to my eye the left arm is unusally close the left side of the BB..by a mm or two. This maybe due to the type of bearings that were installed. Who knows what the history is of the bike. But as long as if you tug on the left arm there is no play and the arm isn't hitting the BB...you should be fine.
If mine, I would likely shim the left crank arm with a 1mm spacer as the crank you have it laterally adjustable.

Look like the pics on these Domane

http://www.bikerumor.com/2012/03/30/...bike-unveiled/

http://cyclingmagazine.ca/2012/04/se...k-trek-domane/

Sure does. That be tight.
Bonty padded handlebar is interesting. Wonder if that will be the new trend...

Sorry for no response, I did check and there's no lateral play, it's on there stiff and well and doesn't interfere with anything, I just needed perspective from you good people :)

I think you are fine then as Rob said. Looks tight but apparently is design intent...confirmed by the pic of the Domane which has basically the same BB design.

That's a SRAM GXP crank. The Trek Madone BB was designed solely around the Shimano 24mm crank standard. Apples and Oranges.

I guess it could be accidental that GXP cranks fit, but I think it's more likely that when designing the BB90 spec, they chose to allow it to accommodate GXP cranks.

Note I did point out in my earlier post that this was a Madone 6, but with SRAM cranks.

Quite right. The BB90 spec was developed expressly to accomodate all interations of external bearing cranks which have a long spindle...all Shimano sells. Trek didn't want to design a bike that couldn't mount Shimano cranks.

The main difference in the SRAM GXP is NDS spindle diameter. All Shimano spaced bbs can take a SRAM. It's not that nearly as much as it is the cranks and spacing, which is what people are wondering about in this thread, are not the same. That's all I am trying to point out.