Texas Chainring Massacre report

Half of the fun of mountain biking, for me at least, is exploring and just pedaling for as long as I can be out before life's obligations call me back. The other half is about technical challenges. Sometimes I want to focus on the latter, and I can find plenty of nearby trails to challenge me in that regard. The best way to do the former is a gravel grinder, a popular race/fun ride format that involves riding long courses on unpaved, rural roads.

I have done a few of these over the years, including The Holy Roller, Castelle Grind, and the Texas Chainring Massacre. Previously, I have ridden cyclocross-type bikes that I have owned (Pake C'mute, Salsa Vaya, Soma Double Cross Disc) and, while those bikes have been great for this kind of riding with 32-42mm knobby tires, I took the plunge a few months ago and sold my last CX bike and committed to making my Soma Juice hardtail 29er my only bike. With a little bit of adapting, a mountain bike makes a great gravel grinder. Most of the hundreds of other people riding around me (and past me!) were riding cyclcross/gravel-specific bikes for good reason, but I just wanted to do this for fun and finish these events strong with my bike.

In addition to riding what many will consider a sub-optimal bike for a gravel race, I chose to try this last event, the 2017 Texas Chainring Massacre 100k on a single-speed bike. To make my bike gravel-ready, I had to change a few things from my usual trail setup:

*replaced the 120mm suspension fork with a rigid Salsa Chromoto Grande fork. This fork has a tapered steerer tube like my squish fork, and a 15mm through axle, so I didn't need to do anything different with my front wheel.

[Salsa rigid fork]

*swapped my 60mm stem and 740mm riser bar for a 100mm stem and 640mm flat bar. I also put some bar ends and TOGS. Since most riders use a bike with a drop handlebar for additional hand positions, I felt that this was the next best thing, and I ended up using 3-4 hand positions over my hours on the road

*gearing- this was a tough call. I live in Austin and the event is held in north Texas. I had ridden CRM two years ago on a geared bike and did not remember the terrain well enough to know how much climbing would be involved. Knowing I would not have the options of shifting gears meant picking a gear that would cruise well on the flat sections and be easy enough to pedal up the hills. I went with a 38t front chainring and an 18t rear in place of the 32/20 combo that I usually use. As a bail-out option, I slid a 20t cog on next to the first cog, so that I could wrap my chain around it without too much drama and hobble to the finish on a slightly easier gear.

[big ol' KMC singlespeed chain actually didn't play nice with my Raceface narrow-wide ring, so I put an old 10-speed chain on instead]

*tires- this is, in my opinion, the thing that can make or break a gravel grind experience. I have ridden these events on 32mm Contintal Race Kings, 42mm Conti Speed Rides, and 35mm WTB Cross Boss tires. Every time I do one of these rides, I start to think "man, I wish I had bigger tires on my bike. next time I'll put some fatties on!"

While the Cross Boss has been my favorite "skinny" tire so far (partially due to the effortless tubeless application), I found a good deal on some Schwalbe Thunderburt tires in a 29x2.1 size and chose those over the Specialized Renegades that were competing for my attention. Thunderburts are light, supple, and fast on hardpack and on pavement, and the casing is big enough to roll at lower pressures. They seated easily on my WTB rims and have been grippy enough for some nimble singletrack riding.


The Chainring Massacre experience was my best gravel race yet. Kevin and the Spinistry team have upped their game this year with a much better-organized event than my last experience. There were hundreds of riders, timing chips, well-marked turns on the course for people riding different distances, and credit for free food/ liquor in the little town square at the end of the ride. The route took us through beautiful, remote farm roads and lots of challenging gravel, rolling hills, and folks willing to spin and chat once the group spread out enough.

As I mentioned, hand position options were a great idea for my mountain bike. I am having a harder and harder time making the case for myself that I should ever own a drop-bar bike again when I can ride narrow flat bars with ends and get the same effect (for my purposes, at least, YMMV). Tires were spectacular, I brought plenty of snacks and water, and I dressed warm enough for the ride that started just about freezing and ended in the low 50s. My toes quickly went numb and stayed that way for the duration of the ride, and I don't recall stopping to pee at any point. Pedaling and drinking water and not peeing for that period of time is probably not healthy.

I managed to finish in just over 5 hours and I was the 200th rider to complete the 100k distance. That is not impressive my any means, but I was riding against at least one Tour de France champion and handicapped myself with a relatively heavy bike with only one gear. I was perfectly pleased with my performance, though. I rode strong the whole time, only stopped once at the lone water station to refill, and didn't walk any of the hills, as much as my legs wanted me to.

Looking back, I would have geared down just a tiny bit to help with the hills (maybe a 19t cog instead of 20t) and shoved some warmers in my shoes to prevent the numbness that plagued me the whole way. Looking forward to next year. Before that, I have Castell, Holy Roller, and whatever urban rambles I can cobble together in the meantime.

[The Juice getting some well-earned R&R]

The versatile Soma Juice- gravel mode

As I mentioned in my last entry, I recently sold my Soma Double Cross Disc not because it was not a terrific bike, but because it didn't do anything that my mountain bike could not. Selling it gave me some extra cash to put into new parts for my Juice. Here's a bit of what I have been doing with that cash lately.

"Mountain bike" means a lot of different things to different people, and many just buy one bike and accept its limitations or buy several bikes that do some things well at the expense of others. As a matter of personal budget, I don't have a lot of disposable income to spend on bicycle paraphernalia, and I would rather have one really nice bike than two or three mediocre bikes. More importantly, I have a fairly utilitarian perspective on my personal belongings. I strive to have as little as possible in my life cluttering my endeavors and I have to make a conscious effort to keep from being a packrat with bicycle gear.

The Juice allows me to build a rowdy trial ripper and a fast gravel grinder by just changing a few things between rides. Yes, it would be easier to own two bicycles, but it would cost a lot more and I would have to find storage for another bicycle. Here is what I have been riding on some non-technical trails and more technical trails than I intended.

I have a little over a month before the Texas Chainring Massacre, which I am riding 100k, and a few months to the 100k Castell Grind. I have ridden these events before on a cyclocross bike with 32, 35, and 42mm tires. Every time I participate in a gravel event on a CX bike, I start to think halfway through, "this would be a lot more fun on a bike with bigger tires!" Now is the time to test that theory.

I bought a Salsa Chromoto Grande fork used for a great deal. This fork has a tapered steerer tube and a 15mm thru axle just like my Reba suspension fork, but it's considerably lighter and more responsive.

The handlebar is a flat Answer bar that I got online for $10 and cut down to about 26", which is 4" narrower than the normal riser bars I use for trails. To make up for the narrower handlebar, I have a 100mm stem, 40mm longer than the 60mm stem I also use for trail riding. I finished the cockpit with some Ergon bars ends. I removed these ends from some Ergon wingy grips. I have no use for the flappy bits on Ergons, but the bar ends will clamp onto a handlebar on their own.

I have been experimenting with single-speed gear ratios for trail riding. 32/20 seems to work for any sort of chunk and climbing, but I have found that I am hack it 90% of the time with a 32/18 ratio as well and go faster on the flat areas. For gravel grinders though, I know that most of the terrain will be flat or at least in a straight line. For this reason, I bought a 38t Raceface front ring and I am experimenting with 18, 19 and 20 cogs on the rear. So far, 38/18 is working just fine. I set a personal record on a long climb with this setup just the other day.

Finally, nothing changes the ride of a bike like a change of tires. I have not ridden them yet, but I just acquired some 29x2.1 Schwalbe Thunder Burt tires. These tires are well under 600 grams each, unlike the 800+ gram trail tires I normally ride, and the minimal center tread should roll much faster on hardpack and gravel roads as a result.

CX on singletrack- followup

I wrote a year ago about riding my Soma Double Cross Disc everywhere, including "mountain bike" trails. While it was a fun experiment, it ended a few months ago. The DCD was a great bike for roads, easy trails, commuting, and gravel races, but it ceased to be sufficiently useful to me after a while.

This bike served to do all the things that I thought my mountain bike would do poorly- commute, roads, gravel, occasional single track. As it turns out, my Some Juice mountain bike does everything I need it to do, hence the DCD becoming redundant.

My current job requires a 20-mile commute each way, so by bike, it would add about 3 hours or more to my work day. While I commend the bike warriors who would make such a commitment to pedaling that much, it's not for me. My wife would be constantly worried about me in traffic, especially in the dark and there's no shower at work to wash off 90 minutes worth of sweat from the Texas sun. At this point in my life, commuting by bike to work is just not practical. Maybe someday things will be different and I will start riding to work again, but I'll get a commuter bike at that time.

Road riding is something I wish I could do sometimes, but I have found that riding a mountain bike on roads can be fun-er! I had signed up for a nighttime gravel race and intended to do it on my mountain bike. I have done several gravel races in the past and always did them on a CX bike (more on that in a minute) but decided that I would have more fun on a hardtail MTB this time around. The race ended up being cancelled due to heavy rains, so I ended up doing a mixed-surface, 4-hour ride in the pouring rain with a friend. We mashed just short of 50 miles and riding mountain bikes made us fearless to hop curbs, ride through the soggy grass, and smash through some ditches.

bar ends, frame bag, and DIY fenders all seemed necessary!

I rode the 62-mile Castell Grind  this spring on the DCD. I had a ton of fun crushing 100 kilometers of remote central Texas country roads. The weather was perfect, my recently-installed WTB Cross Boss tubeless tires performed wonderfully, and the course was challenging. I found that having skinny tires floated over the hard-packed parts of the roads swiftly, but this course, like most of the gravel courses I have ridden, has just enough soggy sand pits and stretches of washboard surfaces that it really took a lot out of me. It left me thinking "wouldn't this be more fun with a flat handlebar, balloon tires, and a squishy fork?" The answer is probably yes.

The only real hill on my 100K Castell Grind.

Singletrack where I live is pretty darn chunky. Even the flat "easy" sections are peppered with exposed rock and boulders that keep me on my toes. While riding the CX bike on singletrack was a fun new challenge, it was a bridge too far. I would frequently have to slow down so much to tackle the terrain that my front tire would catch the toe of my shoes, something that never happens on my mountain bike. Toe overlap was never a problem on my mountain bike, but ratcheting over and around rocks on my CX bike was disastrous for the tips of my shoes. As fun and fast as it could be, I realized that all of it would be a lot more fun on my mountain bike.

After all that consideration and looking at the deteriorating condition of my mountain bike, I concluded that I would rather have a few hundred bucks in my pocket to spend than a bike that doesn't offer the maximum number of grins per hour. A nice local gal bought my DCD and is commuting around town on it now. I hope she loves that bike as much as I did.

A good day to stick to the roads.

back from the real world!

I have not been sleeping well lately. Last night I woke up at 2 a.m., like most nights in the last few weeks, and could not shut off my brain. I was thinking about bicycles, of course. I spun in bed like a stuck pig in a blanket with a lot of ideas boiling in my head. "You should blog this stuff, bro," my conscious intoned. I considered the phrase "my conscious intoned" and decided to time-stamp that gem. 3:49 a.m. My eyes are burning under their lids, but still no asleep!

You can't will yourself to sleep. I find that if I am fixated on something, that persistent jerk in my head won't let go. (Who is that guy, anyway? Get out!) I finally got some sleep, but not before I outlined some objectives to write about to get this blog rolling again. Hopefully my findings will be of some help to other riders and mechanics.

To bring readers (all 4 of you) up to speed, I was working at an independent bike shop about this time last year. The general state of disarray of that shop was my inspiration for this blog. I combined my past experiences of what was good about past bike shops and juxtaposed it to all things that were wrong and unfixable with that shop and started writing.

I worked at that shop for one month and it was a letdown on several fronts. Providence smiled on me a few weeks in when someone from a newspaper company called me about a job. I had been working in bicycle shops for the past six years (minus a 6-month foray as an apprentice commercial electrician, which was a hoot!) after being laid off from a magazine gig at the beginning of the "great recession" in early 2009. I loved the bike shop jobs, but, as I have written, it's generally a low-paying career choice and I wanted my Journalism degree to count for something. For the past year, I have done some writing and proofreading for publications.

This is a trajectory for my career that makes sense, pays more (but not much), and gives me weekends off and enough time in the mornings to squeeze in a short bike ride. It's not as fun a wrenching on bikes, and I don't have ready access to deeply-discounted bike parts like I did, but it all comes out in the wash. Nitpicking newspaper pages is actually very satisfying to me.

I was not surprised to learn that, less than a year after I left my previous bike shop for the newspaper gig, that bike shop went out of business. It's sad to see another independent bicycle shop go, but I saw a lot of issues there that I knew would have that result. Those issued inspired me to write in the first place, so we have that. I hope everyone previously involved in that shop is doing well.

I have a few ideas in the hopper so stay tuned. Coming soon:

• review of the Soma Double Cross Disc and the limits of cyclocross bikes
• review of the Soma Juice I have been riding
• more retrogrouch ranting
• thought experiments (and actual ones, hopefully) in mountain bike fit and geometry

Avoid tubeless disasters

There is high demand among mountain bikers for tubeless tires on their bikes, and for good reason! Anyone who has ever ridden a bicycle has experienced a mid-ride flat tire. Since these are relatively rare on pavement with a good quality tire and proper installation, I will leave road tubeless alone for now. I want to focus today on tubeless tire for off-road applications where riders are concerned with thorns punctures and pinch flats.

The beauty of a tubeless system on a mountain bike is that the latex-based sealants available will seal up most punctures caused by the local vegetation, and eliminating the tube means there is no tube to pinch in a hard impact. This means riders can ride worry-free through over-grown trails and run much lower pressures to increase traction on the trail. Many who are used to pumping their tires to 35-40 psi to avoid pinch flats can enjoy a grippier, softer ride at pressures below 25. The feeling is liberating and many bike shop customers will ask their local shop if a) the new bike they are eyeing is "tubeless ready" or b) if the shop can convert their existing wheels and tires to tubeless.

As I have seen, many bicycle mechanics are all to eager to please and are willing to "convert" a rim and tire combination to a tubeless kludge. Consider the results of a badly done tubeless conversion: your customer happily starts riding after you return the freshly converted bike. He or she drops the tire pressure to 24 PSI and decides to test the system on the local trails. As the rider gains some confidence and rails a tight turn, the tire slips off the rim. If the rider (and the mechanic responsible) is lucky, the tire merely "burps" some air and the rider has to top off the pressure at the next stop. Otherwise, the rider could crash, causing bodily harm and damage to the bike. The shop that did the work could get negative reviews or face a lawsuit. This is a lose-lose for mechanics and customers.

The other reason to refuse to do questionable conversions is productivity. Anyone who as attempted more than a few conversions knows that some take longer than others. A conversion should take no longer than the time it takes to wrap the rim in tape, install a valve, mount a tire, squirt some sealant, and inflate the tire. You should not have to struggle to get a tire to inflate and seal. Inflating the tire should take no more than one minute- if it takes longer, the tire and rim combination is somehow sub-optimal and will likely not stay sealed and inflated.

Basically, inflating a tubeless tire needs to result in a tight fit on the "shelf" of the rim. If the rim is not designed to form a tight enough seal or the rim is fitted with a strip that sufficiently seals it, the movement that results tire failure what could be catastrophic. Stan's has an excellent article on the topic here.

To minimize the chances of a tire failure, let's first lay out what NOT to use in a tubeless conversion:

• "Cheap" tires- in a professional setting, I would not attempt a tubeless conversion on any tire that has a wire bead, or any tire that is not somehow identified by the manufacturer as "sealant compatible" or "tubeless ready," or at least otherwise known to be a good quality tire with strong casing. Some tires are known to break down chemically with some sealants, which is why Kenda identifies some of their tires at SCT.
• Rims that are not designated as "tubeless ready" by the manufacturer, unless used with an appropriately chosen and installed tubeless rims strip, such as Stan's strips.
• Tire/ rim combinations that are known to be problematic. You will need to do some research on this, but if the mounted tire is impossibly tight or incredibly loose, the end result will be bad.

Manufacturers have developed several options and "standards" for tubeless tires and rims, and not all of them are compatible with one another. I will not go into very disputed merits of each system, as I am primarily concerned with compatibility. The most common tubeless interfaces you will find are:

• UST- Universal System for Tubeless. This system requires rims and tire casing and bead to be manufactured with narrow specifications to be considered UST.
• BST is Stan's NoTubes design is intended to allow riders to use "regular" tires in a tubeless system. It is found on their ZTR rims, and on a few licensed products, notably Sun-Ringle (click "Features"). Stan's rim strips can also create a BST-type interface when done correctly.
• "Tubeless ready" is a bit murkier. Most "tubeless ready" tires have a bead similar to UST specifications but without the airtight casing and therefore require sealant to work. Wilderness Trail Bikes' TCS and Bontrager TLR designs might fit under this category.
• "Ghetto tubeless" is a DIY kludge involving the use of a split inner tube, various tapes, home-brewed latex sealant, and other methods. Some of these methods work wonderfully for riders, but should never be done in a bicycle shop.

The final but equally important issue to consider is how well any particular tubeless-specific tire will fit and seal on any particular tubeless-specific or converted rim. I have found that BST rims and Stan's rim strip conversions do not play well with UST, TCS, or several other "tubeless ready" bead tires. I witnessed the anguish of a friend trying to fit some WTB TCS tires on his Stan's rims recently, breaking several tire levers and very nearly breaking some fingers in the process. The bead on most rims with a bead based on the UST design is simply too tight to fit reasonably on BST rims (Stan's agrees with me here), so I don't recommend trying those.

If you are ever uncertain about what kind of materials are needed to successfully convert a rim to tubeless, ask the manufacturer directly. If it causes your customer to wait an extra day to get wheels back, it will be worth it to both parties to do it right rather tan compromising in the name of expediency. For example, I just noticed that Alex manufactures several rims (MD21, for example) with their Tubeless Ready System or TRS, which they describe as "Tubeless Ready System = Universal Valve + Rim Tape + Sealant," but they fail to specify what tape and valves are to be used. That kind of specificity may seem absurdly fastidious to some, but a good bicycle mechanic makes or breaks a career on that fastidiousness. [I will follow up with Alex on this topic.]

Whatever you do, make certain that you understand how tubeless systems work, what combinations and techniques work the best. Set standards for your shop so that everyone on staff is on-board with using the same techniques so there is continuity from the sales floor to the service writer to the mechanic and back to the customer. Your shop and your customers will be happy.

addendum 5 July, 2018: I recently had my Schwalbe mountain bike tires leaking a lot of air in spite of a proper tubeless rim, tape, valves, and sealant. I sprayed soapy water on the tire and rim to locate the leaks and noticed fine bubbles all around the sidewalls of the tires. I pulled the tires off the rim and discovered that the Truckerco sealant I have been using had not reached the inside of the tires' sidewall at all, but had concentrated on the middle of the tire tread.

Suffice it to say that the "tubeless dance" you're supposed to do it important! when installing new tires, turn the wheel sideways in your hand so the rim is parallel to the ground. Roll, swish, shake, dance a little gig to slosh the sealant all over the inside of the tire. Schwalbe sidewalls are notoriously thin, so really coating the inside of tires like this is especially important. I have not tried "painting" the inside of the tire with sealant, but I might try that with an actual paintbrush in the future.

The other bit of advice is to avoid tires with very thin sidewalls. As nice as lightweight tires feel, tires that hold air consistently are preferable.

cyclocross on singletrack

Much has been said lately of riding mountain bike trails on bikes designed with racing through muddy grass and hopping over barriers in mind, but not carving a ribbon of hard-packed dirt and rocky ledges. The allure of beating yourself up on such terrain caught my attention too, so I tried it a few months ago.

Unfortunately, my Salsa Vaya was fitted with 42mm knobby Continental Speed Ride tires at the time and it did not take long before the rocky crust of central Texas claimed one inner tube. By that, I mean I was on the trail for less than 15 minutes before a rock killed my tube. I patched it and kept riding, but the experience was somehow stilted from that point forward. I became paranoid that another misstep was going to bring my fun to a grinding halt. I put roadie tires back on that bike after that and kept it on the pavement, leaving my mountain bike for those off-road adventures.

Vaya- great stable bike for long rides on road and gravel

After some more months on that bike, I decided that the Vaya was probably a terrific touring bike, but I was not touring anywhere loaded with camping gear; just zipping around the city and riding as much dirt and gravel as I could find along the way. After a lot of over-analyzing with spreadsheets, in-depth interviews with fellow riders (forums, that is), and the discovery and subsequent obsession over bikegeo.net, I decided to get a Soma Double Cross Disc.

Double Cross Disc- a subtly but noticeably different bike!

This frame would easily accept all the part from my previous build with little drama and featured angles and features I thought would make it better suited for road and trail riding. It does all those things well and Soma makes a great product. For a long time, it served primarily as a commuter and road bike with skinny slick tires, fenders, and sometimes a rear rack. Something in me still wanted to beat myself up on singletrack with it though, but the thought of pinch-flatting myself out of the fun was holding me back.

The impetus for finding a tubeless solution came while riding my mountain bike. I lost all pressure in my air sprung fork and even blew the seal off the fork during a ride. I guess I should have paid closer attention to that service interval schedule.

oops

I did not want to take up precious riding time rebuilding a fork, so I got a hold of some WTB Cross Boss tires. I picked these after hearing a lot of reports of how incredibly tight-fitting the WTB TCS bead tires are on Stan's rim. One rider I know spent several hours and shattered a tire lever or two trying to fit some WTB tires on he Stan's rims, so I knew they would likely be a sufficiently tight fit on my non-tubeless rims (DT Swiss x430). Sure enough, a layer or two of 1" Gorilla Tape, some Velocity tubeless valves, and some home-made latex sealant got these to grab the rim and not let go.

patented skull valve cap

these fit surpisingly well on my rims

just enough tread for singletrack, smooth enough for pavement

On my first ride on these, I could not help myself. I rode about 40 miles of (mostly) singletrack on the local urban trail system, complete with rocks, ledges, and loose gravel. Riding a bike like this on rugged terrain is certainly different! It is not for people with bad backs and poor bike handling skills. You have to pick your lines carefully. A mishandled ledge can buck your off the bike pretty easily. The tires don't grab the dirt like you are used to. Bumps that come faster than you can soak them up with your arms and legs, usually the job of a suspension fork, build up and force you back on the brakes. If the gnar gets too gnarly, you have to get off and walk, which is part of the cyclocross experience.

On the other hand, you can go much, much faster flat sections and non-technical climbs. I went for a second ride with two friends who were on rigid mountain bikes and I smoked them up a non-technical hill, only to realize at the top of the hill that I never bothered to shift out of my big (48 tooth) chainring! If your trail system includes sections of pavement between trail systems, the "boring" slogs feel like less of a drag and more of a go-fast interlude.

Will the 'cross bike replace my mountain bike? certainly not! Certain trails and types of dirty terrain are lots of fun on a bike with drop bars and skinny tires, but you have to know it's limits. There are parts of the trails that I ride that I would never ride on this bike, and this is one of them:

I did that once trail and will probably not do it again for a while, until I get the urge to beat myself up again.

Results? Riding my mountain bike after this ordeal was a bit strange. The handlebar felt very high, the front steering a bit vague, even though it was just above the saddle height. I have since lowered my handlebar a bit and it feels a lot better- closer to the stability of the 'cross bike but with the advantage of fat rubber and a suspended fork.

Logs are there for a reason- trail leads to the left

Inspection- save time and make money!

It is rare, but I have been in several situations where I have made some, if not a lot, of progress on a bicycle job, only to find that the work will be fruitless due to a fatal issue with the bike. After working on hundreds of bicycles, it's easy to become complacent with the assumption that most bikes are structurally sound. As with the often ignored rim wear issue, it is easy to miss or over-look a cracked or damaged frame.

A few embarrassing examples:

1. A customer dropped off his son's entry-level mountain bike for a tune up. Try as I might, I could not get the linear-pull brakes to center on the rim. The rim was true and had been "dished" correctly. The pads were spaced correctly. The spring tension was balanced. Finally, it struck me for the first time- the frame! I placed our trusty Frame Alignment Gauge (a surprisingly cheap tool), on the frame and discovered that it was twisted. Oddly, the customer was incredulous that it could have been damaged, "My son just got home from his freshmen year at college where he was just riding that bike to class..."
2. I performed a fairly detailed tune on an older aluminum road bike, only to discover that they NDS chainstay was cracked cleanly in half right at the dropout weld. The customer got some sort of warranty reimbursement, which he hopefully put toward a new bike from my store, but I wasted about two hours of labor on the bike because I did not check the frame for cracks first.
3. My store ordered a whole new drivetrain and other components for a customer's beloved old touring bike. After the magical box appeared, I got to work, eager to see this bike reborn. Sadly, I found a small crack in the chainstay behind the bottom bracket. The frame was toast and the shop had to send all the part back to the distro at our expense.

cracked frame is cracked

This is all to say: inspect all bikes thoroughly before making grand claims about how awesome the bike is going to be when you are done with it. To be clear: it is in the shop's best interest to refuse to do any work on a bike with a cracked or compromised frame. Use your judgement, and don't put yourself in a situation of liability when a bike shatters under a customer, causing injury or death, because your expert opinion neglected a compromised frame.