The Golden Wrench

A blog about bicycle repair and maintenance by the mechanics at Freewheel Bike.

Tuesday, October 30, 2012

Salsa Chili Con Crosso BB30 Issues

If you have a Salsa Cycles Chili Con Crosso with a press-fit BB30 bottom bracket you may want to bring it in for a little service. These bottom brackets have an issue with the cup that holds the bearings coming loose and then making strange noises while being ridden. The solution for this is to Loctite the bearing cups into the frame.

In the building process the Bottom Bracket is being pressed in without a retaining compound. Then after force is applied, like riding, the cup that holds the bearing in place comes loose and spins in the frame.

This is what happened when we took the crankset off of a brand new Chili Con Crosso from the West Bank location. While pulling the crank out the cup came with, this is not good.
Drive side Bottom Bracket cup pulled right out of the frame.

This is what the frame will look like, see how half the bearings are now just sitting in the frame. These need to be taken out as well. If nothing is done it will eventually come loose and we have to do this process over again.

Non-Drive side cup still in frame waiting.

Using the fantastic Park Tool BBT-30.3, we can knock out the other cup and then Loctite that cup in as well.

BBT-30.3, the tool for the job.

Now that we have both cups out we can start the process to reinstall them.

Press-Fit BB30 cups with no frame.

Using Loctite 609 and Loctite 7649 Primer, we can make the bearings stay in place. Using the primer cleans the frame surface, and hardens the Loctite quicker. After the primer dries the Loctite is applied and the cups are pressed back in.

The needed Loctite for this operation.

This is what the frame looks like after the cups are back in the frame.

A Chili frame with cups in place.

All that is left is to wait for the Loctite to dry and then reinstall the crankset. This is a problem that is happening on Salsa Chili Con Crossos with a Press-fit BB30 Bottom Bracket. If you have one then it might be a good idea to bring it in so we can take a look and see if you need some Loctite.

Thursday, October 25, 2012

 The crew at Shockspital have been getting a lot of requests to tune Fox rear shocks from XC racers that are riding Trek bikes. It seems that over the past few years Fox rear shocks have had less "platform". The Pro-Pedal seems to have been dialed down leaving these bikes suffering from excessive pedal bob. The problem is that Fox does not yet allow anyone to service their rear shock dampers. This not only prevents us from tuning the dampers but it prevents us from servicing them when they go bad, and they seem to go bad more than other brands. Our solution is to replace the Fox rear shocks with a Rock Shox Monarch. The following is a review from one of our team members.

"First, let me describe myself as when I read reviews I like to know that riders bike and riding style is to see how it applies to me. I am 6'2", a fit #195 pds and an aggressive rider. I race on weekends in the Midwest. Lots of single track, some hills, berms, ruts, and rock gardens but overall, no big west coast drops. I have raced with this shock on tight single track and long 100 mile endurance rides. I ride a 2012 Fisher Superfly 21 inch frame. The bike came with the Fox RP23 shock but I kept blowing out the damper seals and needing it overhauled every couple of months. In addition, the Fox was to plush for me. 
   Shockspital (part of Freewheel Bike in Minneapolis) suggested I try the Rock Shock Monarch RT3 shock.  It fits the same as the Fox on the Superfly. I went with the medium compression tune as it offers the widest range of damping adjustment. It is also what the guys at Trek recommend for my bike. The staff at Shockspital are aware that I am a aggressive rider (take the most direct route from A to B) who wants a more planted, stable feel through corners which the medium compression offers. I have not tried the high or low compression tunes so not sure how that would affect the compression. I am not a techie person so I will not get into the details of the "guts" of the shock, but rather how it performs for me.   One word "AWESOME".    I have raced on it for the past 6 months and have not needed any service. I set the sag at 20% which for me was about 175 psi. Make sure you measure the sag with the platform set at OFF. The monarch has gradients on the shock making it easier to set up sag. No more need to use zip ties. I must add that 20% is pretty firm and have set it at 25% if I am hitting a very rough course (ie Afton for those who are local).  No leaks to date. A plus is that the compression lever  is longer than other shocks I have tried, making it easier to adjust the rebound setting. The platform settings are more distinct than the Fox float and I use all 3 settings.  It also has a red dial to control the rebound. Rabbit for fast and turtle for slow. I have mine at setting 4.     
     Unless I am racing down a steep rock garden or over ruts, I have the compression lever in  position two or three. I keep the rebound in the 4th setting. What I notice on the tight single track is that it gives me a stiffer feeling in corners, it does not compress as much and feels more responsive. The shock seems to "roll" over the ground which provides for much better traction. I make the analogy that my old shock felt more like a Buick suspension (some riders like that) but this is more of a tight responsive European car feeling. The old shock felt more sluggish, this is more lively and gives me more control. I used to bottom out my compression on berms but the Monarch feels more firm but still compresses when you hit the "big stuff". 
     I am also able to pump out speed with this shock in flowing single track trails. Also, on hills or flats I do not get the peddle bob, allowing me to conserve more energy. At 195 lbs, I need all the help I can get to chase the younger 160pd racers up the hills. You feel the added control and power. I have ridden the bike on courses with lots of ruts and notice that it is sensitive at the start of the stroke, it absorbs the small bumps well. 
      Bottom line, I get the best adjustability for the terrain I am riding. The feel of a hard tail for climbing hills, responsiveness in tight single track, excellent cornering but then can lower the compression when the trail gets rough. Setting 3 is almost a full lock out but it still gives you some suspension for going up a rocky hill but feels firm. 
Try one out, you will not be disappointed."

If you would like to upgrade your rear shock to a Monarch you will need to know  the length of the shock  from eyelet to eyelet, referred to as eye to eye, how much the  shock needs to be able to compress or stroke, the width of the frame mounts or end width, and the bolt diameter.  For Trek bike that information can be found here. Then you have to decide on your tune. If you aren't sure what tune you need Shockspital has rental Monarch shocks so that you can try before you buy. Once you know which one you want you can order it here.                                                                                                              

Saturday, October 6, 2012

How I spent my day off

So it's Thursday evening, about two hours before close at Midtown when we receive a frantic phone call from the airport.  There's a marathon this weekend, and a woman that flew into town from Spain to compete (one of Medtronic's Global Heroes) has a big problem: the airline crushed her hand cycle and broke it.  After calling bike shops and wheelchair/handcycle shops all around the metro, Courage Center gave them our number and said to ask for me. The woman calling wasn't sure exactly what was broken, but would I please look at it?  You bet.  How much time do I have to repair the bike?  It needs to be at the starting line in exactly 36 hours.  Oh boy...

The hand cycle was transported from the airport to Midtown by a limousine driver a half hour later.  When the driver opened the trunk, I had to ask him if this was the whole bike, or if perhaps we're missing the rest of it.  I'd never seen such an alien unicycle-like contraption before.  This was the whole thing, he assured me.  He said he's done some unusual runs before, but this one probably tops the list.  Once I got it down to the bike shop and examined it more closely, I deduced that it clamps onto the front of a wheelchair to turn it into a tricycle.  I've worked on several hand cycles, but never this type before.

My heart sank a little when I examined the broken part; the non-drive crank arm was snapped in two.  And this is no normal crank arm; it's made from the sawed-off hub portion of a normal square-taper crank with a custom arm welded on.  It broke at the weld, an inevitable weak point.
If it was made of steel, I could have it over to Peacock Groove and Erik Noren would have it TIG welded back together in no time flat.  But it's aluminum, and nobody I know is willing to do weld repairs on aluminum bike parts due to the tricky metallurgical complexities involved.  The manufacturer, Stricker Handbikes, is straight out of Germany, and their website is only partially translated to English.  I doubt they'll be able to help me out in the tight timeframe available.  Thus far, no spare parts or loaner bikes could be located anywhere nearby, so I began formulating a plan.  This was no normal bike shop repair; I would be spending my day off at TC Makers' Hack Factory, a shared shop space in South Minneapolis.  They have the precision heavy machinery, and I have my personal collection of tooling and accessories.  Time to make a part from scratch...

At about 11am Friday, I paid a visit to Amble's Machinery & Hardware and picked up a block of aluminum billet the size of a kleenex box.  It was the smallest piece Jim had that would do the job, but it was still much larger than I needed, so I sliced off a piece in the bandsaw to work with.  My hand is for scale; I don't normally put my hand in the bandsaw...
This is an old Shimano non-drive crank from the junk bin.  It's going to donate a square-taper interface to the cause so I don't have to try to machine the taper and extractor threading, which I'm not equipped to handle.  I faced the back of the hub, bolted it to a 1-2-3 block, and clamped the block in the Bridgeport vice at an angle so the original crank surface was level.  Then I machined the top perfectly flat and created two parallel flat surfaces on the sides.
 Here's that piece of billet again.  I faced all six sides flat and square, then started making a groove down the middle the exact width of the squared-up section of crank arm.  Careful measurements and a few very light finishing passes later, I had a perfect slide-on fit with less than a thousandth of an inch of play.
 After some careful angle measurements on the unbroken drive-side crank, I decided where to cut off the excess and set up the bandsaw at a 30 degree angle.  I left plenty of extra material for later when I would be adding pinch bolts.  Just ask any barber; you can always take a little more off later...
Back at the mill, I used a 30 degree angle block to machine a flat surface on the block and step-drilled a hole to within 1/8" of the diameter of the broken crank arm shaft.  I neglected to take a photo while finishing  the hole to final diameter with an adjustable boring head, measuring progress with a telescopic bore gauge and my favorite digital micrometer.  I stopped when I was within a thousandth of an inch to check fit with the actual part.  Too small; take another thousandth off.  A perfect snug sliding fit!
Everything fell into place in the nick of time for this repair.  I was interrupted from machining about a dozen times during the day by a representative of the airline requesting info about the bike to try and find parts or a loaner.  When I was about 2/3 finished with the part, the representative finally called for the last time to inform me her leads were all spent, and she was giving up.   Now this strange adapter I'm making from plans in my head is the only option.  The day is passing quickly; it's crunch time.  I stopped documenting my progress and worked as quickly as I safely could.

Here's the mostly-complete part, sitting on the remainder of the billet from which it came.  I have already drilled holes for pinch bolts to go through the stub of the new crank arm and to clamp down on the cylindrical old crank arm part.  I would have made it lighter by taking off more material here and there, but I was running out of time. 
Here's the finished assembly at about 7pm Friday, after a whole day in the machine shop.  I did the concept and design work in my head, made a few simple sketches, and pretty much went from one logical step to the next until I had a working part.  If I goofed up anywhere along the way, I certainly wouldn't have time to start over again.  Fortunately, everything went perfectly.
This is Anna and I at about 8pm Friday night, in the lobby of the Crowne Plaza Hotel in downtown St. Paul.  I hand-delivered the repaired Stricker handbike and did the final assembly in the lobby.  Anna was very excited to be back in action after fearing that she was out of luck.  After a few quick shifting adjustments and a crude on-the-spot derailleur hanger alignment with pliers, she was ready to tackle the race course in the morning. 

I have to stress that this particular project is not the kind of repair we typically do at Freewheel, but we do have excellent resources and connections for when push comes to shove and the clock is ticking. If you need hand cycle repair work (that hopefully doesn't involve fabricating parts!) give me a call at Freewheel's Midtown shop and we'll talk options.  612-238-4447; ask for Karl.

Anna, I hope you enjoy the rest of your trip, and let me know how the bike performs!

Friday, October 5, 2012

Ancient Mountain Bikes

It's been just over a year since our Eden Prairie store opened up, and we're finally getting to service the bikes that we knew were out there. In the meantime, we built, serviced, and got proficient with the new stuff, but we knew that, for example, Raleigh Technium bikes were hanging like stalactites from the rafters of several area garages. The conversation went like this:

Mechanic: "There are Raleigh Technium bikes hanging like stalactites from the rafters of several area garages. Just wait."

Other Mechanic, from behind a carbon road bike: "OK, I'll just wait."

Time Elapses...

Mechanic: "Should be any time now. Raleigh Technium. Glued together using glue. Al-you-min-eeee-yum tubes glued to steel lugs using glue, you know, to keep them together. The tubes and lugs I mean."

Other Mechanic, from behind a carbon mountain bike: "I'm getting excited. I can't hardly wait."

More Time Elapses...

Mechanic: "Perhaps while we wait we could do some online certification training for Raleigh Techniums."

Other Mechanic: "I'm not here. I went over to the grocery store to get some food a while ago, and I'm standing over in the self-checkout line checking myself out. Hey, check me out! Haha!"

But then the day came when all our dreams came true.

Mechanic: "Look, our dreams are coming true. There's a customer with a Raleigh Technium that has served as habitat for noxious insects since Czechoslovakia was touristy."

Other Mechanic, through a mouth full of grocery store treasures: "Furrrmmuurrr hummmurrr shruutthhunnn rruuuhhhtt uurrrrt."

Just to amuse ourselves, we stuck magnets on the so-called "Al-you-min-eeeeeeeee-yum" Raleigh Technium.

Hee hee hee! Marketing!

Now that we've been here for a while, people are beginning to bring all sorts of historically significant bikes in for repair. I speak for myself, but I like working on the old stuff. When I was a kid I used to catch big air and otherwise violate terms of manufacturer warranty on a 1988 Rockhopper with beartrap pedals, bull moose handlebars, Grippa tires, and Ron Wilkerson signature ODI Mushroom grips. I remember bending the fork on a motorcycle jump. I also remember that my father was somewhat less impressed with me than I was.

Nowadays I smile on the inside when customers bring their ancient machines in and ask "Do you still fix these?"

I love to say "It's not even broken properly!"

Wednesday, October 3, 2012


Have you ever noticed that some suspension forks will come with adjustable rebound damping, but not adjustable compression damping? But there aren't any that come with adjustable compression damping and not adjustable rebound damping. This is for a good reason.

Rebound damping is directly related to spring rate (air pressure). Spring rate is directly related to rider weight, so any fork that has an adjustable spring rate needs to have adjustable rebound damping. Yet whenever the conversation turns to suspension tuning it seems like it's always focused on compression damping. We often see fancy charts like these for different compression shim stacks. A good suspension tuner would know which shims to arrange in what order to make a fork more supple at the beginning of the travel yet resist bottom-out for a light weight rider. Or they could arrange a shim stack that makes your fork resist pedal bob but allows you to use all of the travel. It's really quite fascinating stuff, but honestly, you'd almost need a physics degree to really understand it. Plus I've never owned a fork or rear shock where I had the option of tuning it with shim stacks. I have been content with setting my air pressure and turning the knobs to get my suspension set up correctly.

Like most mountain bikers I like to fix and adjust things for myself. I am also stubborn, in the sense that I have figured out my suspension settings by trial and error instead of looking up the manufacturer's recommendations. It takes me a few rides to get it just right, but I feel like I do a good job despite my lack of formal suspension tuning training.

Now as a bike mechanic I get to see a lot of others peoples bikes and talk to them about their set-ups. I'll be honest (and maybe a bit judgmental), I think a lot of people would be benefit from trying the manufacturer's recommendations. Okay, that was downright condescending, I know, but I am a bike mechanic after all. This is why I am quite excited about the new suspension set-up systems from various manufacturers like Trek and Fox.

Trek came out with their Suspension Set-Up Calculator last year (I believe) and I happened to have been riding a 2011 Fuel EX 9.9 for a couple months. So in the name of professional curiosity, I decided it was my duty to try this new tool. After all, it could make things easier when we sold a mountain bike. No more asking the customer to hop on the bike, then asking him or her to get off without bouncing around, then measuring the o-ring height and trying to calculate 15 % off 110mm (remember, I don't have an engineering degree). So while driving down to Buck Hill for a Thursday night race, I pulled out my smart phone and started punching in some numbers.

When I got there I began setting up my bike according to what the Trek Suspension Calculator said. I was quite impressed, both with myself and the calculator, that the only change I had to make was to back off the rear shock rebound damping by two clicks. Turns out that all my other setting were exactly where the calculator said they should be. So I went out for a warm up lap. The one thing I really noticed was that on one small g-out (okay, it was a little dip on the trail) I kept having to stand up or I would get bucked off the saddle when the rear tire came to the face of the dip. So I turned the rebound knob back in two clicks and voila! I could stay seated through that dip and I actually noticed that the rest of the trail didn't feel as rough.

I had another similar experience recently on my Cannondale Flash Carbon 3. I was riding at Elk River with Tyson Acker from Shockspital, and I kept feeling like I couldn't hang onto my bars very well. I had recently removed a few headset spacers so I thought maybe I just needed to put them back in. But that didn't make sense, because I had ridden it a dozen times since then and I had liked the way it felt. Then I remembered talking to Chris Ames about this same thing when we were riding Red Wing a week or so ago. He had noted that my handlebars were "frowning" and suggested that I rotate them so that the sweep was up in more of a smiling position. So I kept fixating on my handlebars. I have also felt that the stem was too long so I started wondering about the cost of a new OPI stem. But as we kept riding I knew it wasn't any of these things because I have always loved the way this bike feels. What the heck was going on?

Then as we got the the last quadrant of the Hillside trail I started to realize that it was the suspension. As I would descend over stutter bumps my wrists want to buckle and it was starting to get concerning. Then I remembered that Tyson had just come back from a tuning class at Cannondale in Pennsylvania and he kept talking about being able to change out the compression damping shims to fine tune these Leftys. So, I thought to myself, maybe I will have to let someone else work on my bike for the first time since I became a professional bike mechanic.

But that didn't sit well with me.

So I racked my brain as the trail racked my body. What could be different about my bike that was causing this problem? Most of you have probably figured this out by now, but you probably have engineering degrees and stuff. Besides, I was riding my bike and feeling a bit oxygen deprived so my brain wasn't firing on all four cylinders at this point. Then it hit me out of the clear blue! I had used my bike to demonstrate on while giving a lesson on Leftys at the shop recently. For crying out loud! I had turned the rebound knob in a couple turns to demonstrate what is does. IT SLOWS DOWN THE REBOUND, YOU MORON! I backed it out a couple twists while riding and quickly noticed a huge improvement. The trail didn't feel as rough. My wrists didn't want to buckle. My upper body relaxed. I remembered why I loved this bike so much. 

Rebound damping is quite possibly the most sensitive of the three suspension tuning facets. Air pressure can vary by 10-15 psi and the rider might not care all that much. High tech compression damping tuning is complicated. Plus, the compression dampers are really well tuned by the manufacturer from the get go so there's very little reason for most of us to spend money getting a custom tuning job. Rebound damping, on the other hand, has to be spot on. Two clicks off and the ride quality can go suffer tremendously. The weird thing is when the rebound damping is off, the suspension feels harsh. 

Here are some links for more information on how to set up and diagnose your suspension.