If there is one place in the world to find the top mountain bike mechanics in the world it is at a World Cup Race. Well, Dirt Norco Race Team mechanic Alastair Beckett was nice enough to go through rear derailleur adjustment for us at the Leogang World Cup. So, if you have ever wanted a little bit of help fixing up your Sram drivetrain, watch through this easy, step-by-step video tutorial.
It doesn’t happen often but every once in a while I will admit I get caught on the trail without a tube. Not because I didn’t have one, but because I either gave it away or flatted more than once on a ride. I am slightly ashamed to have admitted this but yes, it does happen. This past weekend I went out riding in Port Moody BC with a friend and it happened to be one of those rides. After Eric flatted once, I followed suit. That was no biggie as we both had a tube, but then Eric tried for round two. Three flats, two tubes, 0 patches.
As Eric got ready to start hiking I made a suggestion, one that I am not sure a lot of people have utilized. Tie a knot in the tube and ride out. That is right, this trick is super simple and low tech but can be the difference between a long hike and finishing a great ride.
To fix this flat, you will need to start by finding the hole. Once you do, tie a knot with the hole at the end which is tucked through the knot loop. Pull the knot nice and tight to be sure that it won’t come undone once inflated.
You will see that the tube is significantly smaller in diameter now that it has been tied. You will need to insert the valve, then stretch the tube around the rim before attempting to seat the tire.
Once you get the tube around the rim you can start to work the tire onto the rim. You should be careful that the last bit you are trying to seat is not at the knot as this area has significantly more bulk around it and could be difficult to work with.
Now that the tire is on, you can re-inflate.I wouldn’t suggest inflating to more than 40psi as the tube is significantly stretched and fatigued. This is not a long term fix but should be enough to get you home. Once you start riding you will likely feel the knot as a bump in your tire. It may be a little rough but it sure beats walking.
If you have your doubts, give it a try.
Dustan
There are a lot of standards when it comes to bikes and the number seems to get significantly larger every year. Just look at Bottom Brackets over the past decade or so. We have Spanish BB, Euro BB and Mid BB, we have widths of 68mm, 73mm and 83mm. Mounting standards like Square taper, isis, octalink, Hollowtech II, Howitzer, GXP, and now BB30… I probably missed a couple as well.
Each and every one of these standards serves a purpose. They were each developed with the purpose of making the bike, lighter, stronger, faster or smoother. Over time this has meant that some have stuck, others have failed and we will likely see more coming soon.
This is not isolated to Bottom brackets either though. We have numerous standards for hubs, headsets, bars, stems, posts and more. I will do my best in this series of articles to clear up the most confusing of these.
Over the next couple of weeks I will be discussing the most common Mountain Bike Standards:
WOW, that is a REALLY LONG list…..
Check back soon for the first installment.
Dustan
A loose headset is one of the easiest repairs that can be done to a bicycle. The only thing easier, is screwing it up.
The first step to tightening your headset is loosening the stem. This is done usually with either a 4mm or 5mm allen key. Loosen off the stem bolts until the handlebars will move relative to the front wheel.
The second step is the beginning of determining why the headset is loose. The tightening process may be as simple as tightening a bolt, but it could also be a little more complicated. What you will need to do is take a 5mm allen key and remove the top cap of the headset. This is the vertically positioned bolt on top of the stem.
Once this bolt is removed there should be a minimum of 2mm and a maximum of 5mm between the top of the stem and the steertube. The stem should extend higher than the steertube of which it attaches to. If the steertube extends beyond the top of the stem you will need to install an additional spacer above or below the stem.
Correct Headset Spacing
Incorrect Headset Spacing
Once the spacing has been corrected or confirmed, you may start tightening the headset. The next step is to tighten the topcap to the desired tension. Tightening the topcap is preloading the headset bearings and needs to be completed while the stem is loose. As you tighten this top bolt, you will find that the steering will eventually tighten up and bind. There is a happy medium between a knocking in the front end and this binding stage that needs to be achieved. If there is play in the headset moving back and forth, continue to tighten. If the steering is tight and does not move smoothly, loosen.
The last step of tightening a headset is to tighten the stem. Before doing so you must align the cockpit with the front wheels. The easiest way to do this is to straddle the bike and line up the stem with the front wheel. When this is aligned you can move on to tighten the stem bolts. Be sure to notice the torque rating for the stem as over-tightening could cause damage.
Voila, you just fixed it!
Dustan
Running parallel to the mystery around suspension is the geometry fiasco. What is the difference between a 66 and 68 degree head tube? Why should I care about the seat-stay length?
Recently on Pinkbike.com there was a great post by -Michael “AqueousBeef” Zhao that explains it all.
Have a look: http://www.pinkbike.com/news/bike-frame-geometry-2009.html
Dustan
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