Bottom Bracket Upgrade

Some of you non-bike mechanics may be thinking “Do I even have a bottom bracket?”, “Do I want someone to see my bottom bracket?”, or “Internal may be a better idea.  This is just one of those things that should stay private.”

First of all, any of you that have a bike also have a bottom bracket.  If you have a tandem, you have two! 

What is the bottom bracket?  It’s the spindle and bearings that allow your crank and chainrings to go round and round.  The bottom bracket is housed at the “bottom” of the bike.  Typically, it is 68mm wide with 1.37x24 tpi threading.  Unlike the pedals where the left side is threaded left-handed, on the bottom bracket the right-side is left-hand thread.

Traditional bottom brackets are 4-sided where the crankset is pressed on to the spindle.  Bolts that thread into the spindle press the crankset on to the spindle.  This was fairly reliable, although larger riders sometimes “wallowed out” the crank arm, deforming the softer aluminum against the harder steel.  However, this bottom bracket was heavier and sometimes had too much flex.

An improvement came with the “splined” bottom bracket.  There are three common standards: ISIS, Octalink, and Powerdrive.   ISIS is supported by a few independent companies, where Octalink and Powerdrive are supported by Shimano and FSA respectively. 

The splined bottom bracket featured a larger diameter, hollow spindle, making it lighter and stiffer.  The splined attachment to the crankset was more secure.  This was a definite improvement to the square taper BB.

The latest innovation is the external bottom bracket.  It is called an “external” bottom bracket because the bearing cups are outside the frame.  This spaces the bearing further apart and allows for a larger diameter spindle.  This results in less flex and better power transmission.  As a bonus, it is also lighter.

Note the location of the bearings on this bottom bracket with the bearing location on the previous picture.

The external bottom bracket does not have a spindle.  It is used with a new type of crankset where the spindle is part of the drive-side crank.  The non-drive side crank arm is splined and attached after the spindle is passed through the bottom bracket.

Bolts are used to make a secure clamp to the spindle.

This is a worthwhile upgrade if you have an older bike with otherwise good parts.  Note that the bottom bracket threading is 1.37x24tpi (English) and the width is 68mm.  If you have any other threading or dimensions, you’re probably out of luck.  You may be able to find a new crankset/BB combo for around $150, but expect to pay more.  Or you can keep an eye out for people who have done upgrades and have these for spare parts.

Create Better Gearing for Your Road Bike

Let's just start off by saying that the gearing that comes standard on road bikes is just way too high.  Seriously, how many of you can truthfully say that a 53/39 with a 12-23 cassette is perfectly geared.  If you say this you are either:

A.  A Cat 2 criterium racer who lives and races in the flatlands.
B.  A small Spaniard climber on a continental team.
C.  A delusional wanna-be with blown-out knees.
D.  A liar.

Most of us would be much better off with reasonable gearing.  The problem is that we either as compelled to use racing gearing or touring gearing.  Road bikes now tend to have 50/34 chainrings and a 12-25 cassette.  True touring bikes usually employ a mountain bike crank (44/32/22) with a wide range cassette (11-34).  We usually need something in between.

With the advent of the compact double crankset, we now have a chance if we want to be fast and have reasonable gearing.  How do we do it?

First, let's start with the 50/34 compact crankset.  A 50 tooth chainring is plenty big when paired with a 12t cog.  This is actually a higher gear than the 52/13 that was a common top gear thirty years ago.  If you're sprinting with a 120 rpm cadence in this gear, you'll be going 41 mph.  Not many of us can sprint that fast.  Including Cat 3 racers.

So the high gear is good, even more than we need.  Let's look at the low gear.  If we have a 34T small chainring paired with a 23t cog, this gives us 39 gear inches.  If you don't know what gear inches are, don't worry.  We'll only use these as comparison.  Let's move to a 26t rear.  SRAM sell a nice 12-26 cassette that's relatively inexpensive.  That gets us down to 34.5 gear inches, an improvement of 12%.  Okay, much better. 

But we've got this one really steep hill...

Okay, how can we get a lower gear.  We can change to a triple crankset.  That's expensive and adds weight.  We can change out the rear derailleur and cassette to accommodate an 11-34.  Good idea, but still expensive and maybe a bit of overkill.  We can use a larger rear cog.  No, the cogs all connected together and they don't make them any bigger that a 12-27.  Besides, it says my rear derailleur won't work with a cog bigger than 27t.

Hah!  Here's what we'll do.  First of all, a short cage derailleur will work okay with a 29 or 30 tooth cogs.  A little adjustment may be needed.  Second, we can take apart these cassettes.  On a SRAM PG950 cassette, these are three screws through the body that can be removed with a 1.5mm or 2.0mm Allen wrench.  So if we take apart a 12-26, we have 12, 13, 14, 15, 17, 19, 21, 23, and 26 tooth cogs, assuming we have a 9-speed.  I think the 14 is of little use to us.  Let's pull that out (along with the spacer) and get a 29T Miche cog.  Yes, they do make one and it's only about $8.  Re-assemble the cassette to the wheel (don't worry about replacing those little screws) and you're ready to go.  Now you have an 11% lower gear than the 26t and a 21% lower gear than the 23t. 

I may be the only person in the State of Illinois riding with a 12-29 cassette, but it's certainly much more practical than the 12-23.  Now I know I'm not the only person in the country with one, since I set my brothers bike up the same way.
Now you know there are more options for gearing out there.  Don't be stuck in a gear too high.

P.S.  SRAM has just come out with their new Apex group.  With a standard setup, you can have 50/34 paired with a 10-speed 12-32.  And if you're willing to swap to the MTB rear derailleur, you can go with a 12-36 cassette.  A salute to all of you at SRAM! 

Miscellaneous Ramblings

I ran my first race of the year yesterday at McKendree College over in Lebanon, Illinois.  I know, technically it's McKendree University, but I'm not convinced.  Anyway, they have a spring fling race every year with a 5k, 10k, and 10-mile runs.  This race is a bargain at $12 and a pretty well run race as well.  I finished the 10-miler in just a hair under 1:31, right at the 9:06 pace I need to finish a half marathon in under 2 hours.  I guess training does make a difference since last year I finished the same race in 1:46.

Earlier this week I was in Houston and had dinner at a place with many, many beers on tap.  I had a couple of my favorites, Boddingtons and Old Speckled Hen.  Both of these are nitrogen pressured light ales.  Nitrogen is what gives Guiness that creamy texture.  Boddington's is a very light ale and Old Specklen Hen is slightly darker and heavier.  Both are excellent when you can find them on tap.

Next week is the Metro Tri Club's Tracks n Treads off-road biathlon at Southern Illinois University-Edwardsville.  It's a 5k run on the SIUE cross-country course followed by 9 miles of mountain biking on the single track trails. 

I decided to pre-ride the course last weekend and see what it was like.  I dusted off the old Cannondale and headed out to the trail.  I discovered that you really need brakes to ride the single-track fast.  So this week I gave the mountain bike a full brake service job, which included replacement of the rear rotor which got bent sometime through the years.  The secret of good disc brakes is proper adjustment.  The rear was set fairly loose for clearance of the bent rotor and the front was just set too wide.  I also found that both brake cables had frayed at the clamp on the brake assembly.

So, after two new cables, one new rotor, and a good bit of adjusting, my brakes are working well.  We'll see if my running and biking ability is tuned as well for the race on Saturday. 

If you're interested in the race, see the website:  http://www.teamgodzilla.org/. 

Tires and Pedals

It's time to start getting the bike ready for spring.  Last weekend, I attended the St. Louis Bike Expo over in Collinsville, IL.  There were a lot of shops out selling new equipment, plus clubs and other selling used and "vintage" equipment.

I was looking for tires and pedals.  I needed new tires because one of the relatively expensive Bontrager Hardcase tires on my bike has developed a bad "bump".  The tire is starting to come apart from the inside out.  This is very disappointing, as the tires do not look to be terribly worn otherwise.  And even though the tire was a bit heavy, I had zero flats over 3500 miles.

Anyway, I did not find any tires I liked at the expo.  I did order some tires this week from Jenson USA.  I am fond of 700 x 28 tires, and Jenson has some Serfa Seca's on sale for $9.99.  But they are pink.  More specifically, they have a pink stripe and lettering.  I ordered them anyway.  They should contrast nicely with the sky blue frame on the Gary Fisher.

Back to the pedals.  I have been looking for pedals since I broke two different sets last year.  I had been using SPD-type mountain bike pedals.  My shoes had drillings for either SPD or Look-type pedals.  I remembered that I had a set of Look pedals from 1985 that had served me well until 2000.  I also had an old set of shoes with the cleats.  I replaced the cleats on my shoes and cleaned and re-packed the bearings on the pedals. 

I had forgotten how great of a pedal design these things were.  Look was the first to make a clipless pedal.  They orignally made ski bindings and adopted a design for cycling pedals.  I believe these were first used in the Tour de France by the La Vie Claire team in 1984, led by Bernard Hinault and Greg Lemond.

Easy in, easy out, and secure grip.  I remember purchasing these after my feet came out of a toe clip during the final 200 yards of a race.  These were great pedals, even though they were a little heavy (518g).

So, as I was wandering around the expo, I found a guy with a bin of these, including two pair of the original white with the removable axle cap on the outboard bearing.  Here's a page from the 1985 Performance Bike catalog.

I bought two additional sets of these pedals at $5/pair.  Provided I can keep finding the replacement cleats, these "vintage" pedals should take me well into my my twilight years of cycling, even after my son tries to put me into the home and I keep escaping on my recumbent trike.

The Look pedal is one item that no one has been able to improve over the past twenty-five years.

Santa Brought New Wheels!

Actually, Santa just brought some parts.  As noted in some of the earlier posts, Shimano 105 hubs and Velocity Synergy rims.  And some spokes, rim tap, and a new set of cassette cogs.

I also acquired a new tool:   a Park Spoke Tension Meter.  One of the keys to having a true wheel that will stay true is having even and sufficient spoke tension. Most broken spokes result from duty cycling at the spoke head.  When the wheel goes round, the tension goes up and down.  This is like bending a paper clip back and forth until it finally breaks.  By keeping the spoke tensions high, this duty cycling is greatly reduced.  It also makes the wheel a lot more solid.  In general, the spoke tension is set by the rim manufacturer's recommendation.  In this case, I contacted Velocity and was provided a recommendation of 110 kgf for the front and 120 kgf for the rear.

I did make one small change to the wheels from my orginal plans.  On the rear wheel, I went with double-butted 14/15/14 spokes instead of the straight gauge 14.  Many reputable wheelbuilders swear by this.  They claim that the thinner 15 gauge middle section will flex a bit more on hard impacts and lessen the maximum stress experienced by the spoke head.  It cost another $10 for the spoke upgrade, but I decided I would give it a try.

The wheels make the bike look a bit different.  The 32 front/36 rear spokes certainly give the bike a more classic (or retro-grouch) look than the 20 spoke bladed Mavic wheels.

Here in southwestern Illinois, temperatures are predicted to get back into the 50's later in the week, so I'm itching to try the new wheels out.

If you're interested in building your own wheels, let me know and I can help get you started.  It not as hard as it might seem.

The Times They Are a Chainin' (Part 3)

Why do you need to lube your chain?

1. It squeaks and makes noise if you don't.

2. It wears out faster due to metal to metal contact.

3. Prevents corrosion.

4. Prevents intrusion of grit and other abrasive agents.

What other attributes would you like from your chain lube:

a. Doesn't pick up dirt.

b. Prevents moisture intrusion.

c. Prevents grit intrusion.

d. Easy to apply.

e. Lasts a while.

Let's see how some different chain lubes hold up against these criteria.

WD-40 - First of all, this is not a lubricant.  It is a solvent.  It mostly evaporates after application.

           

90 Weight Oil - Great lubricant, messy.

           

Melted Parafin - At one time this was sold in a tin with extra lubricating agents mixed in.  You could set it on the grill and melt it, then dip your chain in, then hang the chain up to dry.

           

Light oil (e.g. 3-in-1) - Cheap, easy to find and apply.  Need to apply before every ride.

           

Teflon spray or dry lube - Great at washing out foreign matter when sprayed on. Lube coat is very thin considering the duty cycle.

Chain lube with wax - This is good stuff. There are many types and some also contain Teflon and lubricants.   

In summary, lube your chain once in a while with a decent lubricant and things will last longer and perform better.

Here's my evaluation chart:

	WD-40	90 Weight Oil	Light Oil	Parafin	Teflon Spray	Chain lube w/wax
Prevents squeaks and noises	1	8	8	6	4	6
Lubricates metal to metal contact	1	10	7	4	4	6
Prevents corrosion	2	9	9	8	4	7
Prevents intrusion of abrasive agents	1	3	2	8	3	8
Doesn't pick up dirt	5	1	1	8	9	8
Prevents moisture intrusion	2	10	7	6	3	7
Prevents grit intrusion	1	2	2	9	3	8
Easy to apply	10	5	6	1	10	8
Lasts a while	1	7	6	6	1	6
Total	24	55	48	56	41	64

The Times, They are a Chainin' (Part 2)

How do you replace the chain?  You need a chain break tool.  Many of the multi-tools that are carried on the bike have one, but they also make single-purpose models.  The chain is assembled with a pin press fit into the plates.  The pin is set between four plates (two inner and two outer).  There is also a spacer between the inner plates.  To take the old chain off, you use the tool to push the pin out through 3 of the 4 plates.  Note that some chains have a "power link", that allows chain removal without the use of a tool.  This link is sometimes a different color (gold or silver) for easy identification.  To remove the "power link", the links on either side must be pushed together until the links unsnap.  I usually just find it easier to push the pin out.

Take the old chain off and stretch it out on the workbench.  Take the new chain out and stretch it out alongside.  You'll probably find the new chain is longer.  You'll need to remove a few links to make the new chain the same length.  Always remove an even number of links unless you have a power link (then remove an odd number).  Trust me on this one.

Put the new chain on and you're ready to go.  If you are not familiar with how a rear derailleur works, you might want to take a picture of it prior to removing the chain as the new chain must thread back through the derailleur the same way.  Use either the chain break tool to push the pin back in or use the "quick-link" that came with your new chain.  You may find the chain easier to put on if you shift both the front and rear derailleurs to the smallest cogs or chainrings.  This will give you extra slack to connect the ends.

In the next part of this series, I'll discuss the most controversial topic in the universe, more contentious than politics and religion combined:  CHAIN LUBE!

The Times, They are a Chainin' (Part 1)

Now is the time to start getting your bike ready for next spring.  Most of the parts on your bike are maintenance free these days.  Cable housings have teflon lining, hub and bottom bracket bearings are sealed, and pedals don't need much attention.

However, the chain is the one part that is constantly exposed to the elements and has lots of moving parts.  A typical chain will have around 114 links, all of which have two sliding plates.  The chain has no bearings to reduce rolling friction, so these links are exposed to constant metal-to-metal wear.  Throw in some road grit and your chain will wear out.

How do you know if your chain is worn out?  There are some fancy tools you can use, but it can be done very easily with a ruler.  All bicycle chains have 24 links per foot, sometimes described as 1/2" pitch.  Take a ruler and measure the distance between the center of the pins for 24 links.  A new chain will be exactly 12 inches (24 x 1/2 = 12, right?).  A chain is in good shape until this distance becomes 12-1/16 inches.  Now is the time to order the new chain.  At 12-1/8", replace the chain.  Now.

If you continue to ride with a worn-out chain, the first casualty will be the cassette or freewheel cogs.  The stretched-out chain will not mesh exactly with the teeth and c

What kind of chain should you get?  Match the chain to your rear cassette.  If you have an eight-speed cassette, buy an eight-speed chain.  A nine-speed chain will generally work with an eight-speed cassette, but not the other way around.

Beware of the "fancy" chain, with exotic construction or materials.  These chains are high-priced with very little savings in weight and no increase in performance.  The SRAM PC-951 chain costs about $22 and weighs 300 grams.  The PC-991 hollow pin chain costs $62 and weighs 279 grams.  This is about 3/4 ounce or $853/pound.  If you're this concerned about weight savings, get a haircut, go without socks or gloves, get rid of the handlebar tape, don't take water, or any other number of weight savings ideas.

Up next: Replacing the Chain