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| Ask a Wrench- Saturday, July 2, 2010 |
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If you have a Rockshox Coil U-Turn fork and you want to replace the spring to a softer or harder spring but didn't how, click on Read More to learn how to do it yourself with very simple tools you probably already have...
Step 1- Figure out the type of fork you have and purchase the appropriate Coil U-Turn spring assembly. In this example, I have a 2010 Coil Lyrik U-Turn which came with the stock medium spring (red) and I wanted to switch to a softer spring (yellow). Your local bike shop should be able to order the appropriate spring for you. As a rule of thumb, if you are running your compression wide open to make your shock more supple over the stutter bumps, chances are you need to go to a lighter spring weight. If you are bottoming out on minor landings and your compression is already all the way hard, chances are you need to a heavier spring weight. Step 2- Although you can do the spring switch while the fork is still installed on the bike, I recommend that you remove the fork from the bike so you don't contaminate your brakes with any oil that may spill out of the fork. Step 3- Remove the floodgate knob. This is typically held on by a 2.5mm hex. There are 3 springs and 3 ball bearings inside the flood control knob that acts as adjustment detents. Be careful to not lose these as they can be hard to find if they do fall out. Set the parts in order on a clean towel away from the work area.
Step 4- Using a 5mm hex, loosen the footnut at the bottom of the left leg a few turns but not all the way off.
Step 6- Using a rubber mallet, firmly tap on the footnut to loosen the bolt. This will release the spring from the lowers. Remove the footnut and set aside.
Step 7- Using a 24mm socket, remove the top cap of the Coil U-Turn assembly. When removing the spring assembly from the top of the fork, be careful to not damage the o-ring that is right beneath the top cap.
Step 8- Grease the coil of the replacement Coil U-Turn assembly. I like to use silicone grease as this does not break down in fork oil as easily as regular grease. You can get silicone grease at any hardware store as it's typically used for plumbing.
Step 9- Before installing the spring, put some shock oil (SRAM 5 wt) into the upper and lower to replace any that may have spilled out.
Step 10- Reinstall the new spring in reverse order. Grease the threads on the top cap and footnut and make sure they are torqued to specifications. Check the SRAM website for the appropriate torque values.
Reinstall fork on the bike and make sure that everything is tight (headset, brakes, wheels, etc...) and take it for a test ride. I typically put a zip tie on mine to check the amount of travel I'm getting while I dial in the fork.
Happy Trails and have a great July 4th!
Becky B from Bend, Oregon (although for all that knows Becky, she's definitely still a local at heart), asks: I'm going to get a new fork for the VooDoo FS to see if I like it better. I'm so out of the loop on forks and was REALLY hoping for some dumbed down info on a couple. I'm looking at the Fox Talas 32 or the likes of that. Something that has adjustable travel. I think the Talas has 100/120/140.
Dear Truly Crazy Redhead,
TALAS 32 is a great fork, as is the RockShox Revelation -- it would be hard to go wrong with either one. The Magura Thor might be worth a look, as well, but I don't know much about it.
TALAS comes in a couple of flavors: 9mm quick-release and 15mm QR. The 15mm makes the front end track better, and really reduces twist and 'walking' of the fork. The catch: your existing front hub won't work with it.
The Revelation comes in 9mm quick release and 20mm thru-axle. Same deal --- 20mm is much stiffer, but requires a different hub.
From a cost perspective, it's kind of a wash. The TALAS is more expensive, but weighs a bit less. The Revelation is arguably easier to work on, but unless you plan to do the work yourself, that may not be all that important...
The Revelation steps down in small increments (15 or so clicks of adjustment), so if having intermediate travel settings is important, the Revelation might be what you want. The flip side of that, is that the TALAS drops to 100 in 2 clicks -- takes way less time to get there, which might be valuable in races, etc.
Both the TALAS and the Revelation have similar tuning knobs: rebound damping on all models, some compression damping on some models. The Revelation can be locked out remotely, which the TALAS doesn't offer (yet)...
Either of these forks would work well with that bike, so it's bells-and-whistles kind of differences. I would give serious thought to going with the thru-axle model, even though it adds some cost -- you ride aggressively, and could benefit from the added stiffness.
Hope that helps a bit...
Tom G from Boise has a follow up question on last months thru axle question: Dear Wrenches Simply put, thru-axles add lateral and torsional stiffness to forks and rear stays. This increased stiffness comes at a slight weight penalty, but can make a noticeable difference in the handling of your bike.
Forks commonly use 20mm and 15mm axles, and require a hub that will accommodate the appropriate axle size. Virtually every hub manufacturer out there offers a 20mm hub, and most are making 15mm hubs available as that becomes a more common offering. Some hubs (King, Hope, Hadley, Industry 9, DT-Swiss) can be easily changed between the various axle sizes, and make attractive choices if you have a number of different axles in your fleet of bikes.
Maverick and Cannondale also makes forks with proprietary thru axle hub requirements. Also, please note that the axle width for 20mm hubs are 110mm, while the axle spacing for 15mm hubs are 100mm. the same as standard 9mm QR hubs. This means that not all 20mm hubs are convertible to 15mm but it is likely that 9mm QR hubs can be converted to 15mm.
Thru-axles also show up in the rear wheel -- common sizes for the rear are 10mm and 12mm. These axles also require a hub sized specifically for the axle, and 12mm axles require a larger dropout. The usual suspects (Hope, King, Hadley, I9, DT-Swiss) make conversion kits for their rear hubs, allowing you to easily switch between the TA and quick release appropriate to your frame. All modern frames can take a 10mm thru axle for the rear wheel as it uses the same dropout and spacing as a regular 9mm QR.
Note: between us, we've each got at least one wheelset that's built using hubs from the manufacturer's mentioned -- talk with your local shops to select the hubs that are right for you, your bike, and your riding style.
Tom G. from Boise asks:
I have a 2007 GF HiFi Pro. It has Manitou Minute fork. I would like to upgrade it to something with adjustable travel, better performance and maybe a little beefier (i broke mine once already as some wrenches may recall). But a new one is not in my budget. So my big question is how do I figure out whether a particular fork that I see on Craigslist or somewhere will fit my bike? Looks like important variables are things like steer tube length & diameter, whether it has a thru axle etc.. Any particular recommendations. Hi Tom, Whether a fork will work for your bike depends on a number of things:
Your particular bike was designed around the G2 Geometry which necessitated a special Manitou fork (custom fork crown offset). Changing to a non-G2 fork will probably change the handling of your bike which may not necessarily be a bad thing based on what handling trait you are looking for. The 5" travel forks that we've really liked are the Rockshox Revelation (although the newer Revelations are now 150mm forks). If you do get the 150mm Revelation, try getting the U-Turn feature so you can crank the fork down for climbing or if you wanted to retain your current geometry. This fork is also available in the 20mm thru axle/Maxle. Although this will require a new front wheel, we highly recommend the thru axle as it doesn't add that much more weight and it increases the stiffness and steering precision noticeably. The Revelation is also very easy to rebuild using basic tools. Thanks for the questions and happy trails! The SWIMBA Wrenching Crew.
Today we have a Wrenching tip. If you are installing an adjustable seatpost with a remote or you have a shock that has a remote lockout but your frame doesn't have any extra cable guides, this $2 solution maybe work for you.
On my bike, I had a shock with a remote lockout. Since the bike, a Diamondback Sortie Black, had no provisions for extra cable mounts on the frame, I purchased these cable guides from Home Depot (look for them at the Zip Tie section). They only cost a couple of dollars for a few and they come in different sizes and colors.
Simply route the cable through the guides and then bolt the guides down to your water bottle bosses and route up to your handlebar. It makes for a cleaner appearance than using zip ties to secure the cable to the frame. Make sure that the cable clears all moving parts such as cranks, linkages, and does not bind on the handlebar when turning.
If you have any questions, please contact us at This e-mail address is being protected from spambots. You need JavaScript enabled to view it Happy Trails! The SWIMBA Wrenching Crew Karen from Boise asks:
Hi guys,
What is the best rotor for a rear disc brake. Mine continually rubs, even after each "straightening" and looks like it could be warped.
Karen
Hi Karen,
Rotors can warp due to badly worn pads (metal carrier scoring the metal rotor), or because they get hot under braking, and then cool unevenly (a blast of cold water from a puddle, for example). The rotor can also be prone to warping if it has worn down and need replacing. Warping, of itself, doesn't mean that you need to replace the rotor.
A number of things can cause disk brakes to rub, and the rotor plays a role. But, before you spend money on new rotors, you may want to consider some less expensive fixes.
First, does your braking system provide an adjustment for the pad contact point? Some Shimano, Formula, Avid and Magura systems (and possibly others) allow you to adjust the contact point of the pads within the caliper. This is primarily done to allow you to move the pads closer to the rotor as they wear, but may also be used to pull them back to prevent rotor drag.
Caliper alignment/centering can be a painful process, which is often made worse by IS(International Standard) mounting surfaces that have not been faced (made flat and parallel with a cutting tool). Many shops have facing tools specifically for brake mounting surfaces, so you may want to look into having this done. Fortunately, most fork manufacturers have now adopted the post mount standard which doesn't require facing the disc tabs.
The first step in fixing rubbing disc brakes is to ensure that your caliper is centered over your rotor. If you have post mount brakes, you can first try to 'self-align' or center the caliper to the rotor by loosening the bolts that lock the caliper body into place, squeeze and hold the brake lever to align the caliper, then tighten the caliper body down while still squeezing the brake lever (you can use a rubber band or velcro band to keep the brake lever pressed in while tightening the caliper mounting bolts). If you have IS mount brakes, you'll need very thin shims that you can place between the frame and the caliper that adjust the caliper's orientation on the rotor.
If the caliper won't self align (or you have a single-piston or mechanical system), then you will have to eyeball it -- carefully tightening the caliper bolts in alternating fashion, to prevent the caliper body from shifting. Note that in a single-piston system, you want the rotor as close to the non-piston side as possible to minimize flexing of the rotor when braking.
Another common problem is the accumulation of dirt, brake dust, etc. in the caliper body that can prevent the pads from fully retracting. Carefully cleaning your caliper body and piston may provide some benefit.
You may want to remove and reinstall your rotors. This allows you to make certain that the rotor bolts are properly and evenly torqued. Tighten the bolts in a star pattern, trying to maintain an even tightness all around. If you have Centerlock rotors, make sure that they are properly torqued to the hub.
Some combinations of brake caliper, fork mount, and hub can leave the brake rotor in a position where there is no way to avoid rubbing. Depending on the brake manufacturer (and the hub), there may be a set of shims that you can install between the rotor and the hub that will help with alignment.
Finally, brake rotors are only interchangeable to a degree, as the brake pads and the braking surface on the rotor need to match up for the brakes to work properly. Mismatches can lead to problems ranging from reduced pad life to brake failures. Before you ride on 'mismatched' calipers and rotors, please have your brakes inspected by a knowledgeable mechanic.
That said, we've had good luck with the following rotor:
Dave from Boise asks:
Greetings Wrench Crew,
I am quite confused regarding tubeless tires and am hoping you can clear some things up for me: What is the benefit of tubeless tires? Do they not get flats? If they do get flats, are they easier(quicker) to fix than tube flats? If they don't get flats, how? Respectfully, Dave from Boise Great questions Dave,
Before we answer your questions, here are the many variations/combinations of tubeless systems out there:
1. UST rim with a UST tire- This is the ideal combination. The UST tire forms an airtight seal with the UST rim profile. With this combination, you will never have pinchflat/snake bite flats but you will still need to run sealant to seal gashes from the tread of the tire (from glass, thorns, nails, etc...). Also, with this combination, there is less of a chance of burping the tire. The disadvantage is that UST rims and UST tires are typically heavier than a regular rim, tire and tube combination.
2. UST rim with a regular tire- With this combination, you'll need to some sealant as regular tires are not air tight and the sealant also help seal the tire bead against the rim. Also, most tire manufacturers do not recommend this approach as the regular tire's bead is not designed for the UST rim profile and the sealant can also damage the tire over time (voiding the tire warranty). This combination is also prone to burping in some rim and tire combinations. The advantage to this combination is that it is lighter than the typical UST rim and UST tire setup.
3. Regular rim with a tubeless strip and a UST tire. With this combination, you can use your existing rim with a UST tire. The disadvantage to this combination is that only a few rim manufacturers offer tubeless strips (Bontrager and DT Swiss offer tubeless trips for most of their rims) and the tubeless kits can be expensive. Also, since the strip takes up some rim width and depth, it can be an effort to install UST tires. The advantage to this combination is that you do not need to purchase a new UST rim or wheelset to benefit from tubeless tires.
4. Regular rim with a ghetto strip (inner tube or duct tape system) and a UST tire. With this combination, you can use virtually any existing rim with a UST tire. As with the third option above, since the strip takes up some rim width and depth, it can be an effort to install UST tires. There is also a level of effort involved in installing the ghetto strips that is more involved than option 3. The advantage to this combination is that you do not need to purchase a new UST rim or wheelset to benefit from tubeless tires.
5. Regular rim with ghetto or manufacturer's tubeless strips with a regular tire- With this combination, you can use your existing rim and tire but you have to use sealant to seal the tire's bead against the rim and to make the tire airtight. The disadvantage of this combination is that only a few rim manufacturers offer tubeless strips for their rims (and the tubeless kits can be expensive) and if you are using the ghetto system, there is a level of effort in installing the ghetto strips. Also, most tire manufacturers do not recommend this approach as the regular tire's bead is not designed for the UST rim profile and the sealant can also damage the tire over time (voiding the tire warranty). This combination is also prone to burping in some rim and tire combinations. The advantage of this combination is that it is typically the lightest and least expensive way to get into tubeless.
For the best performance and safety, we recommend option 1. UST rim with a UST tire. Additionally, we recommend that you add sealant even if you are using option 1 to seal the tire from goatheads, nails, glass, etc... Also, there are now new UST wheelsets/rims and UST tires that are competitve in weight to ghetto tubeless conversions.
To answer your original questions:
1. What is the benefit of a tubeless tire? Less rolling resistance and pinch flat protection
2. Do they not get flats? Yes, even a UST tire can get flats from running over thorns, glass, nails, etc... However, running sealant inside the UST tire can seal most of these flats except for long gashes on the sidewall or tread.
3. If they do get flats, are they easier (quicker) to fix than tube flats? If you do get a flat using UST tires, the fix is as easy as throwing a tube into the tire to get you home (of course, you have to remove the UST valve from the rim first and any thorn or glass that may have penetrated the tire).
4. If they don't get flats, how? The only flats that UST tires really prevent completely are pinch flats since there is no inner tube to pinch.
Thanks for the excellent questions and Happy Trails!
SWIMBA Wrenching Crew
Jim from Boise asks: I am an upper-middle-aged guy in reasonably good shape who likes to ride trails. My current bike is an older model hybrid, nothing special. It has carried me many miles but is starting to fall apart. (I can relate to that.) I’m in the market for a new bike that helps me along at a reasonable price. I’m thinking full suspension, disc brakes, and 29” wheels. Is there anything specific that will help with the uphill ride, such as an extra “old guy” gear or something? I don’t care about competitions or impressing my friends, but would like a solid bike that will get my tired old self up those steep hills. Any suggestions?
Jim,
There are a ton of options out there, at numerous price points, so the best advice will come from you: go test ride as many bikes as you can. Some shops will let you demo a bike for a day or two at little or no cost, which will let you see how the bike rides on the trails you ride. Some shops limit you to the parking lot, but that's still a valuable little ride, so take advantage of it. If a manufacturer is having a demo event, make sure you attend -- even if you aren't all that interested in their bikes, because you can learn a lot about what you want by learning what you don't want.
There really isn't an old-guy gear. But, there is an old-guy speed: I ride at it all the time... Most modern mountainbikes come equipped with low enough gears to allow you to climb virtually any pitch. If you are looking for super low gears, look for a bike that has a small chainring with 22 teeth and a cassette with a largest cog of 34 or better yet, 36 teeth. The things I would be looking for if I were optimizing a new purchase for climbing efficiency are (in order): - wheels, tires, and cranks: you have to turn these, so you want them light but still strong (which means more expensive). In my opinion, this is the place to spend more money and actually worry about counting grams. - suspension linkage and control: does the rear shock allow you to change the damping and/or lock it out to reduce losses to pedal-induced "bobbing"? If you are serious about climbing as the primary consideration, check out hard tails, which frees up more money for light, strong wheels and cranks. Also, since most of our Boise trails are relatively smooth, a hardtail 29'r is all you really need most of the time. Alternatively, full suspension is more comfortable and on technical trails, climbs and descends better, however, it is also heavier, more expensive and requires more maintenance. The bikes we recommend for you to test ride below have different linkage systems but all climb very well. - geometry: stick to bikes in the XC category. These bikes will (in general) have a geometry that puts the rider into a more aggressive riding posture, and will have head and seat tube angles that are steeper, making the bike a bit easier to control on steep pitches. They also tend to be lighter, and have less travel in the suspension. All Mountain or Trail Bikes have longer travel, heavier components and a slacker head angle which can make them harder to climb than XC bikes. Ultimately, your climbing ability will be dictated more by the amount of time you spend riding, your progression in technique and bike handling, and your willingness to stick with it -- the bike is just along for the ride. Having said that, here are bikes that we recommend for you to test ride. Try to test ride them on actual trails instead of the parking lot/pavement to ensure you get a feel for the handling of the bike in real trail conditions: Specialized Stumpjumper FSR Comp 29 Happy Trails! Mark Hodges and Gary Dinoso If you want to submit a question to our wrenches, you can email your questions to: This e-mail address is being protected from spambots. You need JavaScript enabled to view it Some frequently asked questions are: What are the best tires for XC riding in the foothills? What do you recommend for a light system for riding at night? How do I keep my feet warm and toasty while riding in winter? The mechanics that will answer your questions are: Jason Bauer from G-Fit Studio- Professional Bike Mechanic since 1995. Team mechanic for the Goldie's Women's Road Team during the HP Women's Challenge. Current personal and race mechanic for Rebecca Rusch (2007, 2008 and 2009 World 24 Hour Solo MTB Champion). Race mechanic for Greg Martin (2008, 2009 Singlespeed World 24 Hour Solo MTB Champion). Mechanic and Mechanical Advisor for the Linen District's G-Fit Studio. Professional Level Mechanics, Metabolic Services and Bicycle Fitting Ryan Faber owner of Eastside Cycles- Ryan began mountain biking as a kid and that grew into working on bikes starting at 9 or 10 years old. It was the one thing that came naturally to him as he was growing up. By the time Ryan was in Junior High, he had most of the needed stands and tools and began doing tune ups out of his garage. He had the opportunity to work and learn at a local shop for 9 years working on everything from simple adjustments to the most technical repair. In March 2009, Ryan and his wife opened Eastside Cycles pushing his love for the sport and the industry to the next level. Mark Hodges is an avid mountain biker and has been wrenching on bikes for a couple of years. You've no doubt seen him lying trailside, gasping and bleeding and laughing hysterically. This has never been the result of a poor wrenching decision, at least as far as anyone can tell. He has logged thousands (yes, thousands) of miles on the local trails, and only got lost twice. To be honest, nobody knows why he's included in this list of experts, other than the fact that he's willing to look stuff up for people that are too busy with useful tasks. It's possible that community service is a component of his recent release from an unnamed (but well-known) mental health facility, but he will neither confirm nor deny this allegation. Gary Dinoso- Started riding and wrenching in the late 80's. He is also a mountain bike coach for Performance High, LLC teaching beginner and intermediate mountain bike classes as well as mountain bike maintenance classes. He is a UBI certified Bike Mechanic and Framebuilder.
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