If you noticed that more than one week has passed since I built my studded tires, you are very astute. I have, sadly, only ridden one week on them. A funny thing happened after I fixed my rear tire flat and rode the rest of the week (to Dec 15). I checked the tire pressures on the Saturday and pumped up my front from 20 to 40 psi, then left the bike there in the garage. I drove Monday because I had a meeting to go to, but Monday night when I went out to check my bike my front tire was completely flat!
I had another meeting on Thursday that I had to drive for, so didn’t get to fixing the tire or riding all week, then spent Christmas at home. Finally, yesterday I fixed the tire and have a new 1-week-of-riding update. Here’s what happened:
Front Tire Failure
As with the rear tire, I started my investigation by marking the tire in line with the valve stem so that I could line up the puncture later.
- Pump up the tube so it is somewhat firm ~10 psi, hold it close to your face and rotate it around. You can usually feel the air on your cheek or lips as the hole passes, plus you can hear it leaking. You’re almost kissing the tube when the hole passes by, but it’s easy to find.
- Pump up the tube a bit and fill a pail of water. Dip part of the tube in so that a section (about 4-8″ of tube) is fully submerged. Rotate the tube through the water until you see a stream of tiny bubbles coming up from the puncture. Rotate the rest of the way to catch a possible second hole.
I found my leak, and it was obviously caused by the screw head pinching the tube. For the front tire I had opted not to sacrifice a tube to split and wrap around as protection, so the screws were directly in contact with the tube.
Normally, I would patch the tube by marking the hole with a Sharpie pen using cross-hairs right over the hole. When you use the patch kit, you have to rough-up the hole area, so it becomes difficult to see exactly where to put the patch. The cross-hairs help with this.
In this case, I am going to split this tube and use it as protection for my front tire (just like I did with the rear), so I am not patching it. I’ll use a new tube inside this tube to get protection from the screws.
I took the punctured tube and cut out the valve stem. Then used scissors to cut along the inside seam of the tube, all the way around back to the valve stem.
Then I wrapped my new tube with this split-tube to get protection from the screw heads. I carefully placed the wrapped tube into the tire, making sure that the outer tube was wrapped around the inner one. This part is a bit tricky, so have patience. I tucked in the outer tube so it didn’t stick out once the tire bead was seated.
Possible Causes of Flat Tires
My rear tire flatted, but the puncture did not line up with any screws. However, the front tire puncture was definitely due to the screw head pinching the tube. I had a secondary tube wrapping my rear tire tube, but not in the front, so adding this to the front will probably help.
One thing I’m pretty sure of is that the screws are still too long for studs. I’m sure that when I ride on hard surfaces, they push into the tube a bit, or at the very least are being bent back and forth, causing pinching of the tubes. I’ve thought of a couple ways to shorten the screws after installation, but decided it was too much work. I’m going to ride again for a while and see if I get any more flats. Then I’ll think about shortening the screws as they protrude.
Shortening the Screws
Here’s what my rear tire looks like after one week of riding. You can see that the tips are slightly worn, but the screws still protrude about 3-4mm. I think that the studs do not need to protrude more than 1-2mm, however.
I tried using a medium metal file to file down the screw tips a bit. It worked, but you have to hold the tire and file across the screws, which is a bit annoying. I only did two sets of screws this way.
I then grabbed a pair of side-cutters (and safety glasses) and went about clipping the tips of the screws. This worked well at first and produced a nice looking stud that didn’t stick out too far. Be careful as the screw tips go flying when you clip them. I think my side-cutters became dull, because after about 15-20 screws it became harder to clip them. That’s when I gave up on shortening the studs.
If I end up with more flats that are due to long studs, I may whip out the angle grinder and just touch off the tips of the screws so that only 1-2mm protrudes from the tread. We’ll see if I need to do this.
Number of Screws
A note about the number of screws I used. I’ve read other DIY write-ups that claim you don’t need too many screws. After riding on these tires (192 screws in front, 256 in rear) I believe that you probably don’t need studs as tightly-spaced as mine. Maybe one stud every 3-4″ along the circumference would suffice. Center studs on the front tires are also not as important as they are on the rear.