Crankset/BB replacement

[pirate]

I'm currently attempting to give my old 1998 Trek 4900 a new life as a beater/beer getter. It will be a converted singlespeed to keep it simple.
The last few times I rode it, there was a bunch of noise and play coming from the bottom bracket, so I decided I would replace that and the crankset. (the one that was on there is so old/cheap, you can't take the chainrings apart)
So, I got started tonight by taking the crankset and bottom bracket off of the bike... The problem is, now I have no clue when it comes to either of these parts. How do I know what size bottom bracket will work with my bike? I was kinda looking at this (http://www.pricepoint.com/detail/14316-100_TRUSS5-3-Parts-664-Single-Speed/Truvativ-1.1-Guard-Stylo-Single-Speed-Crankset-'07.htm) because it was cheap, but I don't know how to tell if it will work.
The bottom bracket that came out of my bike is a shimano square taper, that says the following on it:

BB-LP27-E
73
BC1.37 x 24

Can anyone please point me in the right direction?

[jabberwocky]

There are two important measurements: The width of the bottom bracket shell, and the spindle length of the bottom bracket itself. If you have a metric ruler (or micrometer) they are easy to measure yourself:

The bottom bracket shell is the overall width of the piece of the frame that the bottom bracket screws into. Its almost certainly either 68mm or 73mm.

The spindle length is the dimension measuring from end to end of the square taper 'axle' on the old bottom bracket.

Heres the good news: the only measurement you care about is the bottom bracket shell width. The crankset you are getting is an outboard bearing design, which are adaptable to either 68mm or 73mm shells. The cranks will come with spacers, and you install the correct number for your width shell.

The model number of your old bottom bracket indicates that its probably a 73mm shell. I would double check just to be sure.

[pirate]

Nice... I knew someone would be able to help! THANKS!

Have you happened to have seen any better deals out there? I am looking for cheap, easy, and somewhat durable.

[jabberwocky]

For a conversion anything will work. Maybe ask around and see if anyone has an old square taper crank or something? Shimano UN54 bottom brackets are like 20 bucks at most shops, so if you can get a used square taper crank you can get a new bottom bracket pretty easily. I might have an old generic crank you can have.

If you want that crankset, I would personally get it from Speedgoat (its 10 bucks more there, but its the 08, and you get free shipping from Speedgoat so it might be a wash anyway. And they'll ship it from PA and you'll get it in a day). Speedgoat is pretty good about price matching, so they might match the Pricepoint price too.

[jon_baler]

If you want to go external bb, I would consider one of these:

http://www.speedgoat.com/product.asp?part=107251&cat=32&brand=199

http://www.pricepoint.com/detail/13970-100_RACEX5-3-Parts-56-Cranks/Bolts/Race-Face-Evolve-XC-X-Type-Crankset.htm

http://www.pricepoint.com/detail/16431-100_RACSS7-3-Parts-56-Cranks/Bolts/Race-Face-Evolve-Single-Speed-Crankset-2007.htm

Note: speedgoat is free shipping on orders over $100.

I think the RaceFace stuff is better based on my internet research. If you are truly going to use it for limited duty, then either will hold up just fine. The stylo's didn't last me long on my mountain bike (8 months). In the last few months, I've put Race Face on my mountain bike (Atlas) and commuter (Evolve), but too early to tell. You probably want to face the bb shell when going to external bb for the first time (or have a LBS do it). If you buy from them, they might do it free.

[pirate]

I actually already ordered this crankset... (http://www.speedgoat.com/product.asp?part=107606&cat=32&brand=91)
It'll probably break after a few rides, and then I'll replace it with one of the ones you mentioned. :D

[jon_baler]

I actually already ordered this crankset... (http://www.speedgoat.com/product.asp?part=107606&cat=32&brand=91)
It'll probably break after a few rides, and then I'll replace it with one of the ones you mentioned. :D

Hope the bike turns out well. I went really cheap, too, when I first built my beater, just wanted to try out the fixed gear thing with no real plans for riding it. Ended up riding the heck out of it, commuting, touring, riding around the town. Those cranks (low end shimano triple crank, square taper) lasted about 6 months.

Enjoy!

[Dirt]

For a beer retrieval device, those cranks should work just fine.

Pay attention when you're threading in the cups that you get them on the correct side. The drive side threads of the bottom bracket are reverse threaded.

You'll want some kind of thread compound on the bottom bracket threads. Different manufacturer's give different recommendations for what to use. If they don't, I'd recommend a layer or two of plumber's teflon tape since I'm guessing the threads are aluminum to aluminum. If that isn't available, then a little blue locktite. A close third would be just some waterproof grease.

I can't see how those crank arms attach from the photo. I'd look at the "instructions" that come with the cranks and see what they recommend for torque specs. If you follow their spec pretty closely, there's no reason why they can't service you well for years of beer quests.

Hope that helps a little.

Pete

[pirate]

Awesome... Thanks again for the help, guys!

[philvw]

The drive side threads of the bottom bracket are reverse threaded.


Huh? Sure about that?

[Dirt]

Huh? Sure about that?

Yup7654321

Before you try to remove a fixed cup, you must determine whether it has a right-hand (standard) thread or a left-hand (reverse) thread. There are four normal bot-om bracket threadings: British, French, Italian, and Swiss.

Bicycles built to French or Italian standards have a normal right-hand threading for the fixed cup. The normal action of pedaling will tend to loosen a right-hand threaded fixed cup, so they have to be screwed in very, very tightly to keep them from unscrewing themselves. The fact that they are screwed in so tightly also means that it will require a lot of force to unscrew them.

Bicycles built with British or Swiss threading will use a left-hand thread forthe fixed cup. Since the pedaling actionwill tend to tighten a left threaded fixed cup, these are also likely to require a lot of force to remove.

Most American and Japanese frames of good quality use the British threading.

[philvw]

Must have be too long since I tore one out of my bike. I thought it was the other way around, but as usual, I'm looking pretty stupid right now.
Threading from park. (http://www.parktool.com/repair/readhowto.asp?id=94)

[jabberwocky]

I just remember that with the wrench handle pointing up, you push it towards the front of the bike to loosen and towards the rear to tighten.

[pirate]

You'll want some kind of thread compound on the bottom bracket threads...

I see that Park recommends using Loctite #242... Silly question... Where would one buy said Loctite? At a bike shop? Home Depot?

[jabberwocky]

I usually just use some plumbers teflon tape or waterproof grease. Home Depot sells loc-tite if you want to use it (it will be near the adhesives, which are usually in the paint section). Make sure you don't get the red stuff.

[pirate]

Gotcha... I've got some teflon tape at home. I guess I'll just use that.

I'm excited for my parts to come in... This is probably the most in-depth work I've ever done on a bike. <ashamed>

EDIT: Oh, and speaking of learning to work on bikes... I just found this the other day... (http://www.youtube.com/user/SRAMtech)

[Dirt]

Must have be too long since I tore one out of my bike. I thought it was the other way around, but as usual, I'm looking pretty stupid right now.
Threading from park. (http://www.parktool.com/repair/readhowto.asp?id=94)

Nah. It is a very easy mistake to make. After so many years, I tighten and loosen by reflex instead of thinking which way to turn the cups. I had to stop and think when I originally posted about which cup is reverse threaded. When you questioned me, I went out to Sheldon Brown and confirmed because I wasn't so sure of myself.

[Dirt]

Gotcha... I've got some teflon tape at home. I guess I'll just use that.

I'm excited for my parts to come in... This is probably the most in-depth work I've ever done on a bike. <ashamed>


Teflon tape will work nicely.

Loctite is generally cheaper if you buy it from an auto parts store. The cool thing is that it now comes in stick form. That makes it AWESOME and very easy to work with. It looks like a big chapstik. It pretty much eliminates waste. Each stick is very expensive, but it lasts for every. Between car and bicycle projects, I used to go through a large bottle of Blue in a year. I'm now only about 2/3 of the way through a stick that is coming up on 2 years old.

Pete

[jon_baler]

You'll want some kind of thread compound on the bottom bracket threads. Different manufacturer's give different recommendations for what to use. If they don't, I'd recommend a layer or two of plumber's teflon tape since I'm guessing the threads are aluminum to aluminum. If that isn't available, then a little blue locktite. A close third would be just some waterproof grease.


So both of my recent Race Face cranks came with a dry, rubber type film on the threads. Do you still recommend an additional compound?

[Dirt]

So both of my recent Race Face cranks came with a dry, rubber type film on the threads. Do you still recommend an additional compound?

Check and see what Race Face suggests. My personal take on it is that Race Face's thread prep, while adequate to keep the cups from moving without torquing the hell of them, is not as good as it could be.

For the work that I do, I use a little blue loctite to supplement what RF puts on there.

If your cups already have thread compound (loctite) on them, then I would not use teflon tape and definitely don't use grease.

I'd go as far as to clean the threads on the BB shell so that the loctite gets decent purchase.

Make sense?

Pete

[riderx]

If your cups already have thread compound (loctite) on them, then I would not use teflon tape and definitely don't use grease. Why do you suggest no grease? I've combined the grease with the pre-applied thread compound without ill effects and the thread compound still seems to do it's job.

Thanks for the tip on the loc-tite stick, I didn't know they made that. I need to go hunt some down.

[Dirt]

Why do you suggest no grease? I've combined the grease with the pre-applied thread compound without ill effects and the thread compound still seems to do it's job.


From a bicycle perspective, I guess I have no reason not to mix the too. From an automotive perspective the combination of heat, grease and loctite when combined in threads makes the loctite break down. It is a big no-no in automotive applications to mix the two so I guess I projected it onto bicycles.

Good catch! Thanks!

Pete

[mark w]

Nah. It is a very easy mistake to make. After so many years, I tighten and loosen by reflex instead of thinking which way to turn the cups. I had to stop and think when I originally posted about which cup is reverse threaded. When you questioned me, I went out to Sheldon Brown and confirmed because I wasn't so sure of myself.


I've always remembered it by "right is left and left is right". As in Right (side) is Left (hand thread) and Left (Side) is Right (hand thread). This works for pedals and BBs.

As for Loc-tite and grease, I use a thin film of grease to tone red loc-tite down a touch when mounting wallowed octa-link cranks (a real issue with old 950 series XTR cranks). The red loc-tite sets up hard and removes any play but the grease lets it break loose a little easier.

[jon_baler]

I've always remembered it by "right is left and left is right". As in Right (side) is Left (hand thread) and Left (Side) is Right (hand thread). This works for pedals and BBs.

As for Loc-tite and grease, I use a thin film of grease to tone red loc-tite down a touch when mounting wallowed octa-link cranks (a real issue with old 950 series XTR cranks). The red loc-tite sets up hard and removes any play but the grease lets it break loose a little easier.

Aren't pedals and bottom brackets opposite? I think your rule is the opposite for pedals.

http://www.sheldonbrown.com/gloss_p.html see pedals

http://www.sheldonbrown.com/cribsheet-bottombrackets.html

Or am i not fully awake?

[saxman]

I've never used loctite on any of my BB replacements. I just greased up the threads. Once or twice a year, I'll check to make sure the bearing races are still tight (more often than not, they are).

[mark w]

Aren't pedals and bottom brackets opposite? I think your rule is the opposite for pedals.

http://www.sheldonbrown.com/gloss_p.html see pedals

http://www.sheldonbrown.com/cribsheet-bottombrackets.html

Or am i not fully awake?

you're right. opposite for pedals.

[pirate]

I sure wish I had thought about the possibility of needing a special tool for this job... What a dummy. :mad:
To make things worse, the only LBS I was willing to drive to tonight, did not have one either. Major bummer.

[pirate]

So, I thought I had followed the directions pretty well... But it seems like my crankarms don't spin as well as they should after installation of the new BB and crankset. Is there something obvious that I did wrong?

[mark w]

Are the new cranks 3 piece or 2 piece? It's possible to over tighten the arm on 2 piece cranks and cause the BB to bind. For 3 piece cranks, is it a cartridge BB? Those are usually plug and forget but some have a degree of adjustment.

[RetroG]

Must have be too long since I tore one out of my bike. I thought it was the other way around, but as usual, I'm looking pretty stupid right now.
Threading from park. (http://www.parktool.com/repair/readhowto.asp?id=94)

You're probably thinking pedals.

[BottomBraket]

Aren't pedals and bottom brackets opposite? I think your rule is the opposite for pedals.

http://www.sheldonbrown.com/gloss_p.html see pedals

http://www.sheldonbrown.com/cribsheet-bottombrackets.html

Or am i not fully awake?

Here's the way I remember it since I change pedals more often than I change bottom brackets.

right pedal => right hand thread
left pedal => left hand thread

Bottom bracket threads are opposite of pedal threads.

[Dr Phil mmkay]

LOL, 2 for 2 there, BB!:D