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Question for the bike experts re: tire size
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 2015-04-22 9:14 AM |
 15 |  Subject: Question for the bike experts re: tire sizeI am a big Clydesdale guy and have been using my stock 23mm tires pumped to 120psi. This was fine for sprint tri's on mainly nice roads. The roads for my first Olympic were horrible and I was totally beat up at the end of it. I had the MS150 coming up the next weekend and decided I would buy some Continental 4000s in 25mm, pump them to 110psi and see what happens. I had read all the warnings regarding making sure your fork can handle the extra width. I mounted the tires, put them on the bike and had plenty of clearance width wise on the fork but noticed that there was very little clearance at the top of the tire where it goes under the fork. I could see light through there and the tire spun freely so I thought I was ok. We only did half of the MS150 so I did around 70 miles with the new setup. I thought everything was fine but last night I finally brought the bike in to clean it up (got poured on during the drive home). I noticed some squeaking as I was rolling the bike and tried to spin the front wheel. It was definitely rubbing. I took the wheel off and could see where it had been rubbing on the top of the fork (see picture). I have no idea why the position of the tire changed unless my weight caused the wheel to seat more deeply in the fork drop out. So now down to the questions... When I put the wheel back on after cleaning, I have a little play in the dropout. Instead of seating it all of the way in, I pulled it up a bit and locked down the quick release. Is this safe and will it hold? I didn't have time to take it for a ride but will probably put it on the trainer tonight and see if it moves. If that is not safe, is there such thing as a spacer I could put on the fork drop out to pull the wheel away? I am thinking at most 1mm, maybe less. (20150421_185044.jpg) Attachments ---------------- 20150421_185044.jpg (1780KB - 8 downloads) |
| 2015-04-22 10:09 AM in reply to: houtexan |
Master 3127     Sunny Southern Cal | Subject: RE: Question for the bike experts re: tire size Does your front fork have little "cups" into which the nuts on either end of the skewer need to be seated? If you try putting in a shim of some sort between the bottom edge of the fork and the skewer, you definitely want to make sure that the nuts on either end of the skewer are solidly and securely seated within the cups when you flip the cam to fasten down the wheel. As far as what to use, I'm not sure. I've sliced up old tubes and used small strips of those to shim items for mounting on my bars, but that wasn't in any sort of load bearing capacity. Maybe you could find a 23 tire that gets reviews for providing a kinder ride? It probably wouldn't hurt showing what you've got to somebody at your LBS and see what suggestions they have. |
| 2015-04-22 11:00 AM in reply to: houtexan |
Pro 6582  Melbourne FL Gold member | Subject: RE: Question for the bike experts re: tire size GP4000s is a unique tire in that its a bit taller than wider, one of the attributes as to why it's good aero wise when new. Different tire, less psi, or a shim of some sorts all may work. I personally wouldn't put it one without a shim if you need to make some clearance. |
| 2015-04-22 12:27 PM in reply to: houtexan |
Member 1748 Exton, PA | Subject: RE: Question for the bike experts re: tire size I would switch back to 23's. Best option is to use conti 4000S in a 23 which actually measure at about 24-24.5. |
| 2015-04-22 12:41 PM in reply to: mike761 |
Pro 6582 Melbourne FL Gold member | Subject: RE: Question for the bike experts re: tire size Originally posted by mike761 I would switch back to 23's. Best option is to use conti 4000S in a 23 which actually measure at about 24-24.5. Good point. Perhaps use 23c up front and the 25c on the rear. |
| 2015-04-22 2:52 PM in reply to: houtexan |
Champion 10668 Tacoma, Washington | Subject: RE: Question for the bike experts re: tire size It's like the late-80's/early-90's all over again! (Bikes of that era tended to have very little tire clearance, especially in the chainstays.) Anyway... The tires will stretch and open up a bit over time due to the stress of the air pressure within. Not dangerous... unless you don't have enough clearance to begin with. If you could only see daylight between the fork crown and the tire, you'd get the abrasion even if the tire didn't grow a bit -- every piece of sand and grit the tire picks up will sweep by the crown and sand it away. Definitely go back to the 23 up front. You likely can run your pressure a little lower -- 120 is pretty rock hard on 23s even for a clyde. |
| 2015-04-23 8:54 AM in reply to: briderdt |
| 15 | Subject: RE: Question for the bike experts re: tire size Thanks guys. I will go back to a 23 up front and play with tire pressure a bit. I do have a follow up question. The fork is carbon fiber. Why does it look like polished aluminum under the paint? I would expect it to be black all the way through. |
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