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Pinch flat resistance...(10 posts)

Pinch flat resistance...Matno
Jun 18, 2002 8:55 AM
Will I notice a huge difference between tires of various sizes? I've been riding 28's for years, but I just realized how heavy they are (Conti Grand Sports), and I would like to try something lighter. I'm debating going for a smaller size. My LBS recommended 23's, but it was my first time in that shop and I have no idea if they know what they're talking about. The reason I switched to 28's in the first place was that I damaged a rim using the original 23's I had (I can't even remember how they rode compared to the 28's, it's been so long). I also thought I would be doing some loaded touring, but I haven't, so that's a moot point. Now that I think about it, I probably would have damaged the rim no matter what (I was run off the road by a dumb car - my neighbor in fact - and I hit a BIG pothole going fast. Didn't even see it coming).

ANYWAY, bottom line is I don't want to damage my new rims, but where I ride the roads are not smooth. I am a lightweight at 140. I don't race, I just do long rides (60-100 miles). Will I be okay with a 700x23 tire or should I try to find another (lighter) 28?
re: Pinch flat resistance...bikenraider99
Jun 18, 2002 9:01 AM
How rough are the roads? I ride in the Houston and San Antonio area a lot on farm to market roads. Sometimes they're just tar with an asphalt type top on them which usually mean a filling rattling ride. I'm riding 23s right now, and am about 20lbs heavier than you. I've hit many potholes in my riding and it has only been the REALLY, REALLY big ones that have dinged my rim.
Road qualityMatno
Jun 18, 2002 11:24 AM
I grew up in the Houston area. The roads there are heaven compared to here in the Bronx. Yeah, a lot of them, like you mentioned, will rattle your teeth, but here they jar them loose all at once. It's not so much "rough" roads as damaged roads. Cracks, potholes, ripples, the works. It's like riding over curb after curb, except that I don't ride over curbs! Now that I think about it, many of the suburban roads I used to ride in Houston were sectioned concrete. Those gaps between sections can be more annoying than a clingy mother-in-law. I actually got the 28's when I lived in Utah, which has a lot of the tar/asphalt roads you mentioned in the rural areas I rode. They helped, but I'm trying to lighten the bike up a bit and could probably lose close to a pound in my tires alone!

Probably my best solution to this whole problem would be to just hop in the car and drive 15 minutes to smoother roads. New York state has some awesome pavement, but here in the city all our money goes to supporting the cable companies. (By that I mean half of the Bronx is on welfare, so we pay them to sit at home and watch TV. But I'm not bitter...) It sure would be nice to be able to just ride from home though.
re: Pinch flat resistance...Jekyll
Jun 18, 2002 9:19 AM
I don't think that 23's would be a pinch problem (never had that with properly inflated tires and I'm 170lbs). The 23 will roll noticeably faster and will not ride nearly as smoothly as the 28's. I ride pretty rough roads (central PA) mostly on what is alleged to be a bone rattler combo of a Canny frame and Ksyrium wheels. I've had good results with Axial Pro's - they seem to hold up well for a fast tire, corner great and have a fairly supple ride.
If you do loaded touring then 23's may not be a very good option but for a guy who weighs only 140lbs they should work just fine on regular rides. The 28's will protect you rims better simply because of a larger volume of air but most quality rims will last just fine under 23's (big pot holes will do in just about anything).
re: Pinch flat resistance...grzy
Jun 18, 2002 10:10 AM
First you need to keep the tires inflated to their maximum rated pressure - usually 120 psi for high performance tires in the 20 to 25 mm range. Next, try to avoid off roading with your road bike and realize that if you hit something big enough and hard enough you will trash the rim no matter what tire you're running short of MTB DH wheels and 2.4" tires. Personally I run Conti GP 3000's 23's in the summer and 25's in the winter on all sorts of rough mountain roads and have yet to damage my rims. 28's just seem a bit extreme and unnecessary to me. 23's really work well for most applications, but riding style and weight plays a big role. You're fairly light so it just comes down to where and how you choose to ride.
off the subjectcurlybike
Jun 18, 2002 2:45 PM
I must admit, that after you chewed my @ss about the 8&9 Shimano cassette carriers being the same I had my doubts. After looking in the shop I found a 8sp HG D/A 7400 series rear hub and the freehub body is clearly different than the current 9 sp bodies. It even had thread on the exterior for a thread on first cog. The Shimano literature says that an 11t is not compatable with the 7400 series hub. I'm not beind an ass but trying to share info. Keep sharing your knowlege, especially when it is completely correct. Thanks
Way off the subjectgrzy
Jun 18, 2002 3:21 PM
Chewed your ass? When I want to chew your ass you'll know it. I've been ignoring you - any one that responds three times to a reply desperately needs help and attention. To carry it over here is a real indicator on the severity of the problem.

I don't doubt that there are some differences, between the hub bodies - I haven't had my mits on a new one. However, bear in mind that when Shimano went from 8 speed to 9 speed there weren't any immediate changes. In fact there are a huge number of 8 speed hubs being used for 9 speed. So then you're left with the question when is a 9 speed hub NOT a 9 speed hub? You've been able to put an 11T cogset on either an 8 or 9 speed hub since before the 9 speed drivetrain was available and make NO changes to the rear der. setup - the point to which I took you to task for and the one you still choose to ignore.

It really isn't a question of one or the other of us being right/wrong - in reality we're both right and it comes down to which hairs you want to split and which you choose to ignore. You stated the whole thing by saying you CAN'T put an 11T cog on an 8 speed freehub. This is incorrect - many of us have been doing it for years and are still OK people. In fact if you want put an 8 speed MTB cogset on a "modern" 9 speed freehub you're still going to need the 1.1 mm spacer under the stack. The 11T "screw on" cog isn't going to work if the external threading isn't there - duh.

At the end of the day who really needs an 11T cog? It would have to be someone with a very slow cadence, a bike with 650 wheels (usually the big CR is larger) or someone who wants to descend very fast (me). In fact there avre very few road cogsets with an 11T and they're primarily limited to "blocks".
Way off the subjectcurlybike
Jun 18, 2002 4:28 PM
Believe me, I agree with the vast majority of what you have written, I only was trying to tell the original poster that there may be some problems. Remember not all posters here are as mechanically talented as people like yourself. Someone with a real short chainstay may need to make some changes. Others may not be able to add a spacer mentally.
Respectfully yours.
re: Pinch flat resistance...FreakinWeasel
Jun 19, 2002 9:32 PM
Well I have a different situation being 225 lbs. I rode on 23's and went to 28's for pinch flat reasons. I found a tire that has been bullet proof so far. The Specialized Armadillo tire line. They have a range of sizes and offer even a lite version that folds. They run 125psi so compacting the tire into the rim is near to impossible and trust me I have tried on several occasions. I ride mainly hilly areas and long distances with occasional dirt roads. So these buggers have been tested. I did have one tire that had a tread separation issue but I'm 1400 miles into my second set and so far no issue.
Yikes! Those are heavy!Matno
Jun 20, 2002 5:48 AM
The light version doesn't come in 28 and the regular version's 28 is 400 grams! I'm looking to go as much under 300 as I can. I don't want to spend the $$ unless I'm actually getting a noticeable performance gain. Sounds like the Armadillo is a good bulletproof tire though... The 23 lite version is 300 grams, which may be a possibility.