Can my Denali's stock Wheels hold up to a high pressure (130 + psi ) tire and tube(25c)?

[turtletocheetah]

Hey guys, new here

Just got into cycling about a week ago. I am currently saving for a Giant Defy( the cheaper ones in the $900-$1000).

I decided not to wait sitting at home and got a Denali in the mean time. Should have the Defy by the end of the year.
Put over 100 miles so far without any issues. Apart from my fitness level keeping my average super slow (14-15mph) average on 15-20 mile rides. I do understand its only been 1 week since I got into the sport, but I do feel that the 32mm width stock tires (60-70 psi) are not optimal for a faster mph average. i am shooting for at least 16, preferably higher.

Could the stock Vitesse wheels hold a higher pressure tires and tubes of (130+ psi).
I want to put 25mm tires that hold higher pressure to get rid of some rolling friction.
I have heard these wheels (vitesse) will not be able to hold such high pressure because they will crack?

But yet I have seen a few cyclist change the tires and tubes of their Denaili's to higher pressure thinner tires on the same stock wheels with no ill effects.

Any help would be greatly appreciated, last thing I want is to have a wheel give in on me in the middle of a ride at fast speeds using thinner higher pressured tires.


Thank you
Mike

 

[swampy1970]

You don't need to run that much pressure in your tires.

How much do you weigh?

 

[turtletocheetah]

Hey Swampy

I'm 5' 8" and weigh 140.

What pressure do you recommend if I replace my tires with thinner 25mm?


Thank you
Mike

 

[swampy1970]

If the rim is 19mm wide then a 23C tire would be a good choice. If the rim is wider then a 25C would be OK too. Check the rim width, especially since you said the bike came with a 32C. Some of the reviews I looked at about the bike mention schrader rather than presta valves on the inner tubes. Presta valves are the way to go. For pressures - 100psi would be a good starting point. If you do have a rim width d&r than 19psi then try around 95psi. The big enemy with regards to speed on the flat is aerodynamics and not rolling resistance from tires. On hills, rolling resistance does come more into play but there it's weight that's the big factor. At 140lb you should go up hills fairly well when you get fitter. Continental have just replaced their ace GP4000S tire with a newer model - you can pick the older 4000S up for about $30 per tire online. They'll be a huge improvement over what's on the bike right now. It's a fantastic tire for fast riding and they're pretty puncture resistant too.

 

[turtletocheetah]

Thank you for the great info Very appreciated. The rims width (measured from outside to outside rim lip) is 25mm. Would this still be ok for 25mm tires ? Yes the tubes came with shrader valves but when I get new tubes I will get them with presta valves like you mentioned. I will certainly check out those tires, at $30 can't go wrong with that. Thanks again for your help Mike

 

[CAMPYBOB]

Inside the bead hook to inside the bead hook is how rims are measured.

Here's a chart showing a pretty good guide to tire width choice mating to various rim widths.





More detailed information is found here on Sheldon Brown's website: http://sheldonbrown.com/tyre-sizing.html

Let's assume you have a 19 MM inside bead dimension rim under your current 32 MM tires. You can easily, if that is the case, drop to a 28 MM tire. I would not advise going to a 25 MM wide tire unless you have a 17 MM rim ( this can be pushed and fudged a little, but only at some risk and trials for pressure and security of bead seating).

 

[turtletocheetah]

Thanks Campybob Oh, so that's how you measure rim width:/ I am not sure then since I have yet to remove the tire. I will be doing this measurement this weekend. I was really hoping to go down to 25s but from the looks of things seems like these bikes come with 19mm wheels. I will make sure this weekend. Thanks for the chart. I saved it on my computer. Should come in handy Thanks for your help Mike

 

[swampy1970]

That's how some measure rim width Bob - if you look at data from Velocity, HED and Zipp, they list using outside width - and probably a few others do as well. Mavic list their rims with ETRTO width - so the venerable Open Pro is listed as a 622x15. Despite the 15mm inner diameter, the recommend the use of 19 to 28mm tires despite what Sheldon ever had to say. Pretty much every man and his dog ran 18, 19 or 20 mm tires back in the 80s without problems on rims that had an outside width of ~19mm. Just to add fuel to the fire, HED with the latest + rims (25mm external, 20.7mm internal) recommend the Conti Attack 22mm tire for the aero versions of the wide rims (Jet series) whereas tires on Sheldon's list for a 21mm interior rim are nowhere near that skinny. Just stay somewhat close to the outside width of the rim and you'll be OK.

 

[alfeng]

Originally Posted by swampy1970

That's how some measure rim width Bob - if you look at data from Velocity, HED and Zipp, they list using outside width - and probably a few others do as well.

Mavic list their rims with ETRTO width - so the venerable Open Pro is listed as a 622x15. Despite the 15mm inner diameter, the recommend the use of 19 to 28mm tires despite what Sheldon ever had to say. Pretty much every man and his dog ran 18, 19 or 20 mm tires back in the 80s without problems on rims that had an outside width of ~19mm.

Just to add fuel to the fire, HED with the latestf + rims (25mm external, 20.7mm internal) recommend the Conti Attack 22mm tire for the aero versions of the wide rims (Jet series) whereas tires on Sheldon's list for a 21mm interior rim are nowhere near that skinny.

Just stay somewhat close to the outside width of the rim and you'll be OK.

FWIW. My recollection is that 622-13 (i.e., 18mm brake surface width to mimic the brake surface width of tubular rims ... in part, to allow for easier transition between wheelsets) rim size was THE common, alternate clincher size "back in the 80s" produced by MAVIC and others for competitive riders (and, most of the rest of us) vs. all of the porkier "touring" clincher rims ...

My recollection is that the Open Pro's were not introduced until the very late 90s.

 

[swampy1970]

The Open Pros were a very minor rework of the Open 4 CD that were around in the latter half of the 80s.

 

[alfeng]

Originally Posted by swampy1970

The Open Pros were a very minor rework of the Open 4 CD that were around in the latter half of the 80s.

I stand corrected ...

I thought that the Open 4 CD & the Reflex (622-13) were basically the same rim with an 18mm brake surface width.

 

[CAMPYBOB]

Sheldon Brown's chart is conservative.

"Note: This chart may err a bit on the side of caution. Many cyclists exceed the recommended widths with no problem."

The tire size can be fudged a bit as I noted. However, any untried combination of tire, rim and inflation pressure should be approached with some caution. Especially with the department store rims (Alex?) found on the Denalis.

 

[swampy1970]

I stand corrected ...          I thought that the Open 4 CD & the Reflex (622-13) were basically the same rim with an 18mm brake surface width.

I stand corrected ...          I thought that the Open 4 CD & the Reflex (622-13) were basically the same rim with an 18mm brake surface width.

There were 19mm outside - I just measured my old front wheel in the garage.

 

[danfoz]

Originally Posted by swampy1970


There were 19mm outside - I just measured my old front wheel in the garage.

My Ksyriums and Aksiums were both 19mm at the brake track outside-to-outside. Bob's chart looks like it's an inside-to-inside measurement. As rim width increases, and it's marketing becomes more prominent, I have noticed more manufactures commonly referring to the 'outside' width spec (HED, Zipp, etc.)

OP, while a thinner higher pressure will indeed roll faster, do not make beginners mistake #1 and overinflate. Tire pressure should correspond to body weight so if your tire is rated to a max of 120-125psi as many 25c's are, that 125psi is the pressure recommended for heavier riders.(the thinner the tire usually the higher the pressure rating, and usually the higher quality the tire i.e. more TPI, the higher the pressure rating).

Tires need to handle road deformations (so you don't suffer undue fatigue from getting beat up by every pothole), tires need to grip the surface of the road (so you don't end up kissing the pavement), and a tire inflated to max pressure skittering all over the road under a skinny rider will do neither of those things well.

a super hard ball bearing will certainly roll quickly over a glass surface, but a rider/bicycle and the road are neither of those things.

This may help: http://www.bikequarterly.com/images/TireDrop.pdf

PS - I have no idea what the max rating on the Denali rims is, but as one other responder indicated, approach with caution. Unless you are a clydesdale, 110-115psi on a 23c, or 105-110psi on a 25c should be a good baseline for rolling well under most circumstances. Add/subtract pressure based on bodyweight and/or preference, but unless you are 200lbs+, racing on the track, or riding tubulars, imo there's no need for anything approaching 130psi.

 

[turtletocheetah]

I measured it again and I was off last time. Outside measurements were 23mm, not 25mm. So after all that has been replied I am going to take both CampyBob and Swampy's advise. Since the outside width of my rim is 23mm, it will most likely be ok to go with a 25mm tire as Swampy suggested. But since my factory wheels are of poor quality (department issue) I will take CampyBob's advise and keep my Psi pressure conservatively, maybe in the mid range between 90-100. Thanks Danfoz I am only 140 lbs so my initial suggestion to reach 130psi was way off I guess LOL. I'm probably in no danger of pinched flats I will stay within 90 - 100 with the new 25c I get soon and see how that goes. I won't want to go over 100psi, at least not with these cheap wheels the Denali comes with. In any case, the thinner tires of 25c and higher pressure (100psi) should bring my average speed up just a bit. Plus I was told my jersey top was a little loose/baggy on me. So I'm purchasing a skin tight jersey this weekend along with the new tires and tubes. Hopefully I don't feel so much like a slug. In the end I know it's my fitness level and inexperience that is causing my sluggishness in my rides, but a few details here and there will only make me better I think. ( and Ofcourse, a better bike) but that's still a few hundred bucks away Thanks again guys Mike