Bottom Bracket Specs..
 

Just need the BB specs on this bike if anyone knows. Looking into replacing it with a wheels mfg one, but have no clue about the numbers other than it is not a press fit.

https://99spokes.com/en-EU/bikes/trek/2011/top-fuel-8

Thanks,

Trek has a archive that goes back that far. https://www.trekbikes.com/us/en_US/c...uel-8/p/19642/

That says the bike came with a Shimano SLX crank. Which is a 2 piece crank and can use a threaded bb or a press fit bb. So maybe a BB-MT801 will fit.

If you got this bike used, then a previous owner might have put a different crank in it. So looking on the backside of the crank arm and telling use the part number will tell you/us what crank is actually in the bike currently. A Shimano crank will usually have the model number around the pedal hole on the back side. Crank length too. Not that it matters for this. Knowing that the crank is what the specs say it's supposed to be will help.

The BB info a particular Shimano crank uses can be found at http://si.shimano.com/#/

Look in the blue bar near the top and select technical documents. Then knowing that it's older 2011 bike, go to the archives for 2011,

https://productinfo.shimano.com/pdfs...CIFICATION.pdf


Which back then was a SM-BB70. But the BB-MT801 I think meets the same specs. You should double check that though. You need to learn how to research!

Hollowtech II in BSC 73 mm?

https://cimg0.ibsrv.net/gimg/bikefor...4a3f4c211e.jpg
https://cimg1.ibsrv.net/gimg/bikefor...bf662e6a4b.jpg
https://cimg2.ibsrv.net/gimg/bikefor...84113cfd0b.jpg

It looks like a pretty standard BSA threaded bottom bracket, Take out the old one it usually has all the measurements or just measure the actual frame and confirm the width more than likely it will be either 68mm or 73mm. Wheels MFG makes some great bottom brackets and is typically what I run on many of my bikes.

The bike is not secondhand. This particular frame was actually a lifetime warranty replacement from Trek around 2013? The original bike from 2002/03 was a Fuel 90 but had a weakness just above the bottom bracket area so it cracked when riding with a locked rear susp. and so they sent me this, and it hasn`t failed me yet, lol.

Yeah, i have to say i have fallen in love with the angular bearings from Wheels mfg. I hope they make one for this type of BB.

https://cimg5.ibsrv.net/gimg/bikefor...ab50397a8e.jpg

that's definitely a HT 2 Crankset... it will be the 73mm width bottom bracket too... many HT2 BBs come in a universal 68 or 73 kit, with spacers as needed (not all are needed for all installs, tho!)

the Shimano BB has lasted well, if you're just now needing/thinking of replacing it... you might just consider getting another one.... they're about $20 to $30 US, delivered to your door, or in just about any bike shop too.

I think it might be an SM-BB51 ;)

Sm-bb52 is direct (fairly low end, there are better) replacement so specs for that will help. BSA threaded 24mm spindle x whatever length you have now, take it out to measure. Actually just measure across the shell there like in the photo. Probably 73mm.

Yeah, but he's "fallen in love with bearings" (and his AI girlfriend is ok with it)....

This bike is my substitute/reserve bike because my everyday bike has a broken frame all the way back (repairable) This is why there hasn`t been much wear on this here BB. The only reason it needs a replacement is the pedals hit the ground hard a few times because too low pressure in the Fox damper (now fixed) I think i put 260 psi in it, not sure if that is too much or what.

So i grabbed my caliper today and measured the distances. The actual alu.part or frame if you will is 68mm, but the distance between the two silver BB rings is 75mm. I think i can see some plastic spacers/shims in there on the drive side. Perhaps one on the non drive side. BTW, it also says "KC" on the BB. The flash hid it from the other pics i uploaded.


https://cimg7.ibsrv.net/gimg/bikefor...6307b2db4f.jpg

to review with the newest info.,..the BB width is 68mm, the reason you want to spend 5 times as much for a bottom bracket is because your shock pressure was too low, you think pedal strikes kill bottom bracket bearings, and the present Bottom Bracket bearings are, most likely, still in great shape since the bike they're in rarely, if ever, gets ridden, and you forgot to check the SHOCK PRESSURE, and also don't know how to set up the suspension on a spare bike that you've had for over a decade, but have rarely ridden

did i miss any high points here?

i'll take the liberty of jumping forward several steps in this process.... no, you don't need to rebuild the shocks on the bike, but i do ask that you learn to SET SAG on your lonely, un-used Trek.... and 260lbs. pressure is, in all likelihood, WAY too much pressure, and might cause unplanned flights by the rider.
and find a new lover.. angular bearings are not a good idea for bottom brackets... they are finicky and not easily set up. You seem to struggle with set up procedures.
i'd keep loving that lonely Shimano BB... it's been a faithful companion, and hasn't rejected you. yet.

https://tech.ridefox.com/bike

Would this be the appropriate BB for my bike? This is the one that says 68mm. There is also one that says 73mm.

https://wheelsmfg.com/bottom-bracket...ano-black.html

If you have you a 73mm BB shell then that one looks correct if you have a 68mm shell you would want the 68mm version.

Good bottom brackets though!

Any reason i should avoid buying replacement bearings, and rather go for a brand new BB unit. I see Wheels mfg sell loose bearings so you don`t have to buy the whole thing.

Any pro cons?

Given;

• you probably don’t know which bearings you need
• the bearings are probably 75% of the cost of the BB
• bearings standalone cost more than when they’re part of a product
• and it’s a lot more work

I don’t know why you’d even consider it


p.s. Keyboard pedantry alert: also that isn’t an apostrophe key - it should look like don’t

"Direct replacement for Shimano HollowTech II bottom brackets!" on that page seems like a good clue, also the details of spacers so it can be used in a 68mm shell. So yes.

For angular bearings (sealed bearings) i see only three choices from Wheels mfg. The one for my cx bike, they are $17 each, times two plus shipping. A new unit from Wheels is $162.99.

For my MTB bike in this post, the same bearings i would think (24x37) A new unit is $137.99 from Wheels, but here i do not have an MTB BB so i guess i have little choice than to buy one.

Haters welcome..

as noted earlier just replace with a bb52..... $30 it will work with no fussing

https://www.amazon.com/HZBIKE-BB52-C...2143717&sr=8-3

I got an MT801 on the way, but that`s just a stop gap measure while waiting for the real thing ;-)