25 mm wide rim - go wider than a 32 mm tire?

[Number_35]

Hello all. Brought my 2010 Kona Dew Deluxe hybrid out of retirement, mostly because I hate to see it just hanging there, unused. Our roads are such here that the mountain and fat bikes get most of the mileage.

Anyway, the Schwalbe 700 x 32 mm tires feel awfully skinny after the other bikes. Yes, the rolling resistance is low, and the bike is fast, but the ability to gobble up potholes and cracks is not great. I'd like to go with a wider tire if possible. How wide can I go on the factory rims? I don't know how rim width is officially measured, but the outside width is 25.x mm (almost exactly 1"). [Update: The rims are labelled Alexrims DC25. The linked table seems to indicate that the 32s I'm running are too narrow, and that 44 - 62 mm is the correct width range! ]

https://alexrims.com/faq/#1469038581282-feb8f0cf-5e6e

It seems to me I could go up to at least a 40 mm tire without having any clearance issues with the frame, so believe that the width of the rim will be the limiting factor. Thoughts on this?

Thanks in advance!

 

[Surestick]

For road style tires too narrow isn't really an issue until you get into the ridiculous range. On MTB tires you start to create issues with the way the tread interacts with the ground and you can lose traction, especially in turns.

For your bike if it fits in the frame you're probably good to go. That said, you need to keep some clearance, especially around the chainstays, for flex under out-of-the-saddle pedaling where it will rub if it's too close.

Out of curiosity, what tire pressure are you running on your current tires?

 

[Number_35]

For road style tires too narrow isn't really an issue until you get into the ridiculous range. On MTB tires you start to create issues with the way the tread interacts with the ground and you can lose traction, especially in turns.

For your bike if it fits in the frame you're probably good to go. That said, you need to keep some clearance, especially around the chainstays, for flex under out-of-the-saddle pedaling where it will rub if it's too close.

Out of curiosity, what tire pressure are you running on your current tires?

Typically 50 p.s.i. Good point about the tire bulging out under load - static clearance is not the same as dynamic clearance!

Lots of clearance w.r.t. the frame, from what I can see. Looked up the 2010 Kona Dew Deluxe (my model) online - it came standard with 38 mm tires, so I can certainly go at least that wide. The new ones come with 47 mm tires, which would be better yet.

I bought the bike in 2011 from a friend, and replaced the tires in 2013, I thought with like (32 mm). I wonder if he had replaced the original tires, during the year he had the bike, with something skinnier.

 

[Jack Watts]

Hello all. Brought my 2010 Kona Dew Deluxe hybrid out of retirement, mostly because I hate to see it just hanging there, unused. Our roads are such here that the mountain and fat bikes get most of the mileage.

Anyway, the Schwalbe 700 x 32 mm tires feel awfully skinny after the other bikes. Yes, the rolling resistance is low, and the bike is fast, but the ability to gobble up potholes and cracks is not great. I'd like to go with a wider tire if possible. How wide can I go on the factory rims? I don't know how rim width is officially measured, but the outside width is 25.x mm (almost exactly 1"). [Update: The rims are labelled Alexrims DC25. The linked table seems to indicate that the 32s I'm running are too narrow, and that 44 - 62 mm is the correct width range! ]

https://alexrims.com/faq/#1469038581282-feb8f0cf-5e6e

It seems to me I could go up to at least a 40 mm tire without having any clearance issues with the frame, so believe that the width of the rim will be the limiting factor. Thoughts on this?

Thanks in advance!

You're fine running as wide a tire as the frame will allow. Pretty sure that's a single-wall rim, so the more tire protection, the better!

 

[Number_35]

Typically 50 p.s.i. Good point about the tire bulging out under load - static clearance is not the same as dynamic clearance!

Lots of clearance w.r.t. the frame, from what I can see. Looked up the 2010 Kona Dew Deluxe (my model) online - it came standard with 38 mm tires, so I can certainly go at least that wide. The new ones come with 47 mm tires, which would be better yet.

I bought the bike in 2011 from a friend, and replaced the tires in 2013, I thought with like (32 mm). I wonder if he had replaced the original tires, during the year he had the bike, with something skinnier.

GRRRR! Bought a pair of Michelin Protek Cross Max tires - 700 x 40C (622 mm x 42 mm). Installed the front one. Lots of clearance on the sides, but, completely unforeseen, the tire was too tall, and rubbed, at the top of the tire, against the fork at the confluence of the two legs (that is, the bottom of the fork tube - I wish I knew my bicycle terminology better). And that's static, with no weight on the tire. I think this particular tire is quite a large fit - larger than its nominal diameter of 42 mm.

It's weird, because it looks like there's way more than 10 mm clearance between the existing 32 mm tire and the fork. Sigh! I'll try again with 38 mm - I only need the tire to be a wee bit smaller to clear.

 

[NYEngineer]

35, How badly would you like to run these tires? Install a Surly Disc Trucker fork on your bike . Then, on the front, you could run up to a 42mm Surly Extraterrestrial . Does the Michelin tire fit in the rear position?
I do this quite a bit . . . Whatever tire works in the rear and a little fatter up front . Works a treat .

Touring Bike Quick Release Fork | Disc Trucker Quick Release Fork

The Disc Trucker quick release fork is a strong and durable fork option that includes all the mounting points you could want for bicycle touring

surlybikes.com

If you click on a black color option, it is 100mm QR with a disc mount .

 

[Number_35]

NYE, great suggestion! I just ordered one from my LBS Surly dealer. C$175 + tax, which I thought was pretty good. I'll keep the Mchelins, and will consider upgrading the front tire at some point. Many thanks!

 

[Surestick]

Typically 50 p.s.i. Good point about the tire bulging out under load - static clearance is not the same as dynamic clearance!

Lots of clearance w.r.t. the frame, from what I can see. Looked up the 2010 Kona Dew Deluxe (my model) online - it came standard with 38 mm tires, so I can certainly go at least that wide. The new ones come with 47 mm tires, which would be better yet.

I bought the bike in 2011 from a friend, and replaced the tires in 2013, I thought with like (32 mm). I wonder if he had replaced the original tires, during the year he had the bike, with something skinnier.

Not so much bulging under load as flex of frame and wheel under pedaling forces.
Another solution might be to drop tire pressure. There has been a lot of research released recently about tire pressure and rolling resistance and it goes against the long-held belief that higher pressure = less rolling resistance. If you aren't already try using the pressure suggested here when you enter your info:
Silca tire pressure calculator

 

[Number_35]

Not so much bulging under load as flex of frame and wheel under pedaling forces.
Another solution might be to drop tire pressure. There has been a lot of research released recently about tire pressure and rolling resistance and it goes against the long-held belief that higher pressure = less rolling resistance. If you aren't already try using the pressure suggested here when you enter your info:
Silca tire pressure calculator

Surestick, thanks, that's an interesting tool! Can I assume the calculated recommended pressure is optimized for lowest rolling resistance?

 

[Surestick]

Surestick, thanks, that's an interesting tool! Can I assume the calculated recommended pressure is optimized for lowest rolling resistance?

Yes. There's been a lot of interesting research that has been released recently around tire pressure and rolling resistance.
If you want to geek out go here. The TL;DR is:
The idea that higher pressure = less rolling resistance only holds true on a perfectly smooth surface. On anything else, the fact that a hard, high pressure, tire is essentially launching itself off bumps and other imperfections in the pavement means that part of your forward momentum is going into lifting you up in the air all the time. A softer tire will conform to the surface and keep you in contact with the ground not wasting that energy. This comes at the cost of a bit of energy lost to heat deforming the tire carcass.
The interesting thing is that the shape of the pressure vs rolling resistance curve isn't symmetrical and rolling resistance rises much more sharply on the too-much pressure side than on the too-little pressure side so if you're going to err on one side or the other you want to be a bit low.

Obviously, in some situations (mountain biking, cyclocross, maybe gravel riding) you get into a situation where the ideal pressure for rolling resistance means you're getting pinch flats and you have to bump the pressure up a bit but they make products like cushcore for that now so...

 

[Surestick]

Yes. There's been a lot of interesting research that has been released recently around tire pressure and rolling resistance.
If you want to geek out go here. The TL;DR is:
The idea that higher pressure = less rolling resistance only holds true on a perfectly smooth surface. On anything else, the fact that a hard, high pressure, tire is essentially launching itself off bumps and other imperfections in the pavement means that part of your forward momentum is going into lifting you up in the air all the time. A softer tire will conform to the surface and keep you in contact with the ground not wasting that energy. This comes at the cost of a bit of energy lost to heat deforming the tire carcass.
The interesting thing is that the shape of the pressure vs rolling resistance curve isn't symmetrical and rolling resistance rises much more sharply on the too-much pressure side than on the too-little pressure side so if you're going to err on one side or the other you want to be a bit low.

Obviously, in some situations (mountain biking, cyclocross, maybe gravel riding) you get into a situation where the ideal pressure for rolling resistance means you're getting pinch flats and you have to bump the pressure up a bit but they make products like cushcore for that now so...

Actually, this is probably a better link.

 

[Cressida]

You didn't say how much you weigh. That would be part of the equation. If most of your rides are on pavement I would think a 38mm would be a good start.

 

[Number_35]

Per NYE's suggestion, I swapped out the Kona factory fork for a Surly Disc Trucker. Finished this evening - the bike is now sporting Michelin 42 mm tires (nominally 700 x 40C, but also labelled 622 x 42 mm) with lots of clearance. Installed a star nut in the new fork - another first for me. Enjoyed my test ride this evening. The Kona will be my primary trip bike now. Left the stem on the new fork long for now, and added some spacers. Will cut it down later if I feel it's too high. Photos to follow.

Surestick, thanks for the information on tire pressure. I enjoyed the read(s). For what it's worth, I'm about 185 lbs w/ cycling gear including helmet. The bike is fairly light as equipped - perhaps 30 lbs. I carry a backpack of c. 10 lbs, and a pannier (with a shackle lock, cables, and tools) of perhaps 15 lbs, for a grand total of about 240 lbs. The Silca calculator says I should be running 41.5 PSI front, and 42.5 rear. I put it up to about 50 PSI for this evening's ride before checking - will drop it to the recommended and see if I notice a difference.

In answer to my original question, there's no problem at all running the 42 mm tires on the 25 mm (outer width) rims.