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Old 04-08-12, 10:19 PM   #1
bjorke
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Switching my old Dahon to 100psi tires

I'm in the middle of switching my old Boardwalk D6's tires from the original 65psi Kendas to 100psi Comets. I say "in the middle" because after switching the front tire, I noticed that my brake clearance was reduced considerably. A little change I can understand, but could I be damaging my rims?

Thanks!
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Old 04-09-12, 12:49 AM   #2
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there shouldn't be any difference in clearance as you're not changing your rims. it should stay the same. you're just changing the tires, right ? then you should be ok. the only different thing you'll notice is in your ride - from 65 PSI to 100 PSI tires. it will be harsh compare to 65 PSI. unless i am reading your message differently.
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Old 04-09-12, 01:54 AM   #3
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I read the OP's note as indicating that the rim walls were being pushed outward by the higher pressure. If this spreading of the rim walls is significant I'd certainly stop and reconsider using such high pressure. Does the rim maker have any recommendations on maximum tire pressures?
Have the rims had substantial use and possible thinning of the wall thickness due to brake wear?

Rim walls have been known to suddenly split due to high tire pressure, especially after considerable use with rim brakes has thinned the walls. Riding with wheels where you notice spreading of the rim walls is risking both failure of the rim and a possible crash.
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Old 04-09-12, 02:37 AM   #4
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Really? Metal rim walls can just split like that?
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Old 04-09-12, 02:47 AM   #5
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It is said to happen to club cyclists who neglect to keep a check on rim wear. It is one good reason for a) double wall rims , b) disk brakes, c) staying with the OEM max tyre pressures.

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Old 04-09-12, 07:08 AM   #6
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Originally Posted by snafu21 View Post
It is said to happen to club cyclists who neglect to keep a check on rim wear. It is one good reason for a) double wall rims , b) disk brakes or drum brakes, c) staying with the OEM max tyre pressures.
FIFY

Having trouble with caps.

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Old 04-09-12, 08:16 AM   #7
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When the OP says "brake clearance reduced" it's possible bjorke meant the new tires are slightly wider, therefore making it more difficult to get the tire (not the rim) through/past the brake pads, when installing a tire/wheel for example.

I don't know what kind of brakes DaHon had fitted on the Boardwalk, but if they are linear-pull like on my Curve, I can't imagine this being a huge problem; more like a slight bother.

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Old 04-09-12, 11:23 AM   #8
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Wow, a lot of responses! Thanks.

To add detail: I put on the first tire, noticed some binding. The clearances had already been narrow, I could see the pad touching the rim now. Opening up the cable a little solved that, but now -- suprprise! -- the new wider tire is touching the fender, too, and I don't see a solution for that other than to remove one or the other :/

*sigh* if only Kenda still made 65psi tan-sidewall 406's...
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Old 04-09-12, 12:32 PM   #9
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... the new wider tire is touching the fender ... if only Kenda still made 65psi tan-sidewall 406's...
Are the original tires 40-406? What size are the Comets?

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Old 04-09-12, 12:37 PM   #10
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if really ( and I doubt that ) the rim now deflects outwards than most definetely get new rims , as they are worn from the brakes
rims dont bulge out with 40 lbs difference ....

How many miles does the bike have ?
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Old 04-09-12, 11:57 PM   #11
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not many, at least while I've had it. It's my back-of-the-car bike, since the Friday won't fit as easily.

the originals were 40-406, yeah. The main issue now seems to be the fender, the new tires ARE 4-5mm wider when inflated (don't know how to measure the rims)
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Old 04-15-12, 08:46 PM   #12
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The bike is pretty much exactly as the Dahon Brazil archive shows it: http://dahon.com.br/archive/2004/boardwalkd6.htm

I guess I could discard the fenders, but it seems a real waste... oddly I'm having a hard time finding a 65psi 406 20x1.5 tire these days! Any suggestions?
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Old 04-15-12, 09:12 PM   #13
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... I'm having a hard time finding a 65psi 406 20x1.5 tire these days! Any suggestions?
Thor usually has Schwalbe Marathon Racers in 40-406. See:

http://www.thorusa.com/accessories/tires.htm

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Old 04-15-12, 09:45 PM   #14
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oddly I'm having a hard time finding a 65psi 406 20x1.5 tire these days! Any suggestions?
Just because a tire is labeled as having a maximum pressure of 100 psi doesn't mean you have to run it at that pressure. If you find that 65 psi is sufficient for you to avoid pinch flats with a 1.5" tire then you should be able to use any 1.5" tire at 65 psi even if it is rated to be able to take higher pressures.
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Old 04-16-12, 07:50 AM   #15
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Thor usually has Schwalbe Marathon Racers in 40-406. See:

http://www.thorusa.com/accessories/tires.htm

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Yeah, I considered those -- if I want tires that cost as much as the bike did
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