DuncanBeaumont
Senior Member
- Location
- Surrey The Deep South
I swapped to a pair of Schwalbe semi-slicks and found a great improvement.
Road tryes for a cyclocross bike
- Thread starter Powza
- Start date
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PaulSecteur
No longer a Specialized fanboy
- Location
- Walsall, West Mids.
Hmm.... Similar thing going on with the tricross and tyre sizes...
Mavic say up to 28mm tyre (Click on the "Features "tab halfway down)
http://www.mavic.com/en/product/rims/road-triathlon/rims/CXP-22
But Spesh put a 32mm tyre on them (Click on "specifications" and scroll down to tyre)
http://www.specializedconceptstore.co.uk/Detail/11Tricross/TriCross/Tricross Sport
You can see it has the CXP22 with a 32mm tyre.
Mavic say up to 28mm tyre (Click on the "Features "tab halfway down)
http://www.mavic.com/en/product/rims/road-triathlon/rims/CXP-22
But Spesh put a 32mm tyre on them (Click on "specifications" and scroll down to tyre)
http://www.specializedconceptstore.co.uk/Detail/11Tricross/TriCross/Tricross Sport
You can see it has the CXP22 with a 32mm tyre.
Saundie
Über Member
- Location
- Bromley, South East England
I have 32mm Schwalbe Marathon Supremes on Mavic Open Pros which, according to Mavic can accommodate up to 28mm. After looking into it further, I came across a recommended tyre width chart on Sheldon Brown's site, which suggests that 32mm is fine on rims of this size. As gaz points out, those Alex Rims AT450s max out at 25mm, which makes Kona's decision to put such large tyres on them seem highly unusual. I personally wouldn't go above 28mm on them.
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
there are several ways to look at this:-
rim manufacturers website published limits - these are not always the actual rim limits, for example a Mavic A719 shows as 28-47mm, the A317 shows also as 28-47mm, the 19 and 17 denote the internal rim width. Whereas the TN719 shows as 1.5"-2.3" or 37-60mm, this rim has the same specs as the A719. Their Open Pro model, with a 622-15 erto, shows as suitable for 19-28mm but the Open Sport at the same erto shows 19-32mm.
rim stickers - the rim itself has a manufacturers sticker on it denoting the upper and lower limts, the TN719 shows 1"-2.3" or 25-60mm, which is quite a different lower limit to the website figure
Sheldon Browns table of appropriate rim width to tyre sizes
CTC info via Chris Juden around the best ratio between tyre and rim width, he indicates a range of about 1.4-2.2 with around 1.8 being best - you will note that a lot of the MTB/29er stuff goes to an upper limit of about 3.1:1
Along the same lines as the above is the theory around a constant size contact patch and correct profile, also using tyre pressure as a factor. There was a link on here to a table recently, giving a variance between front and rear pressures and also showing that bigger folks really can't achieve these ideals with narrower tyres. However Chris Juden has done a piece where he strongly disagrees with this.
Then you have the tyres that manufacturers actually put on complete bikes, and these may be most telling of all as I'm pretty sure they won't be taking any risks around legal action. My first hybrid came with 622-13 rims and 700x32 tyres, a ratio of 2.5 to 1 and exceeding the recommendations of just about everybody. I had no idea and actually swapped out the tyres for 700x35s, ran these with no problems for many miles.
I pay more attention to this stuff now and do select tyres, for road use, that give a reasonable profile on the rim in use. I have 622-19 rims on all bikes and, for offroad, am happy to go to a high tyre to rim ratio. I would be reluctant to go to the narrow end though, despite the Mavic sticker saying 25mm tyres would be fine on the 622-19 rims, I don't fancy that combo. I did have 700x28s on one bike but have just swapped these for 700x32s, I prefer the ride that gives. How much of that is just the larger tyre/lower pressure potential, and how much is the improved profile within a 19mm rim, I don't know. My other 'road' wheels run 700x42, same size rims, and the ride is even cushtier.
My gut reaction is that you can go bigger on a rim than you may think, as long as you don't go for really high pressures as well, and get a decent ride. Whereas the other end of the scale may/can/will produce a ride that isn't so good.
rim manufacturers website published limits - these are not always the actual rim limits, for example a Mavic A719 shows as 28-47mm, the A317 shows also as 28-47mm, the 19 and 17 denote the internal rim width. Whereas the TN719 shows as 1.5"-2.3" or 37-60mm, this rim has the same specs as the A719. Their Open Pro model, with a 622-15 erto, shows as suitable for 19-28mm but the Open Sport at the same erto shows 19-32mm.
rim stickers - the rim itself has a manufacturers sticker on it denoting the upper and lower limts, the TN719 shows 1"-2.3" or 25-60mm, which is quite a different lower limit to the website figure
Sheldon Browns table of appropriate rim width to tyre sizes
CTC info via Chris Juden around the best ratio between tyre and rim width, he indicates a range of about 1.4-2.2 with around 1.8 being best - you will note that a lot of the MTB/29er stuff goes to an upper limit of about 3.1:1
Along the same lines as the above is the theory around a constant size contact patch and correct profile, also using tyre pressure as a factor. There was a link on here to a table recently, giving a variance between front and rear pressures and also showing that bigger folks really can't achieve these ideals with narrower tyres. However Chris Juden has done a piece where he strongly disagrees with this.
Then you have the tyres that manufacturers actually put on complete bikes, and these may be most telling of all as I'm pretty sure they won't be taking any risks around legal action. My first hybrid came with 622-13 rims and 700x32 tyres, a ratio of 2.5 to 1 and exceeding the recommendations of just about everybody. I had no idea and actually swapped out the tyres for 700x35s, ran these with no problems for many miles.
I pay more attention to this stuff now and do select tyres, for road use, that give a reasonable profile on the rim in use. I have 622-19 rims on all bikes and, for offroad, am happy to go to a high tyre to rim ratio. I would be reluctant to go to the narrow end though, despite the Mavic sticker saying 25mm tyres would be fine on the 622-19 rims, I don't fancy that combo. I did have 700x28s on one bike but have just swapped these for 700x32s, I prefer the ride that gives. How much of that is just the larger tyre/lower pressure potential, and how much is the improved profile within a 19mm rim, I don't know. My other 'road' wheels run 700x42, same size rims, and the ride is even cushtier.
My gut reaction is that you can go bigger on a rim than you may think, as long as you don't go for really high pressures as well, and get a decent ride. Whereas the other end of the scale may/can/will produce a ride that isn't so good.
gaz
Cycle Camera TV
- Location
- South Croydon
Also some tyre companies don't label the tyres as they are. I.e a 28 might be more like a 26.
Good information in that post macb!
Good information in that post macb!
Not tried those, so not sure how they compare... if you're looking at Wiggle, the ones I got are the Kevlar ones here: http://www.wiggle.co...vlar-city-tyre/
£17.59 each
Edit - discontinued... sorry
For some reason Wiggle put the 700x25 Marathons on there own under road tyres. I just purchased 2 for my Tricross - http://www.wiggle.co.uk/schwalbe-marathon-kevlar-road-tyre/
gaz
Cycle Camera TV
- Location
- South Croydon
Those tyres will be fine on that rim.
As I said in an earlier post on this topic, I have contacted both Kona and Alex about the issue of the 700x35c tyres on Alex AT-450 rims fitted to my Kona Jake from new. No reply yet from Alex, but I have just received the following reply from the 'tech' department at Kona:
"Hi, I would not worry about that combo myself. We've run a really wide variety of rim and tire combos the same as or similar to that over the last 10+ years and as long as your brakes are properly adjusted and you tire pressure is correct for the local conditions you won't be experiencing problems. Too narrow a tire can lead to a lot of flats, and way too big (like a DH tire in a XC rim can have a odd profile. Happy Trails!"
No concerns there, it seems about safety issues.
I'll report back on the response (if any) from Alex.
"Hi, I would not worry about that combo myself. We've run a really wide variety of rim and tire combos the same as or similar to that over the last 10+ years and as long as your brakes are properly adjusted and you tire pressure is correct for the local conditions you won't be experiencing problems. Too narrow a tire can lead to a lot of flats, and way too big (like a DH tire in a XC rim can have a odd profile. Happy Trails!"
No concerns there, it seems about safety issues.
I'll report back on the response (if any) from Alex.
Saundie
Über Member
- Location
- Bromley, South East England
So is it fair to say that the manufacturers recommendations on maximum tyre size is almost always drastically underrated? Or is this a dangerous assumption to make?
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
That's a very good question, I've found some old references to rim wall strength and pressures but that doesn't seem to be a concern any more. Most of the theoretical upper/lower limits, as per Sheldon/CTC etc, seem to be about tyre profile in use, ride quality and potential for pinch puntures and rim damage. You'll also get different answers depending on which bike shop you speak to, Spa have some very definite ideas about rim and tyre size. Then you've got to throw the user into the mix, what tyre pressures do they run, do they vary front and rear, do they care and do they vary depending on their own weight and whether they are riding laden or not?
But if you take my earlier example of the Mavic TN719 and the physical sticker on the rim saying 1" to 2.3", or 25 to 60mm tyres...then you've got to imagine that it is well able to cope with these extremes and could probably cope with a greater variance. No way is any legal dept letting info like that go out without it being well within tolerances.
John the Monkey
Frivolous Cyclist
- Location
- Crewe
If it's 13mm interior width, I'd not go bigger than 28;
http://sheldonbrown.com/tyre-sizing.html#width
Whatever Kona say!
A guy who works at a LBS near me has fairly passionately argued that rim->tyre width limits are massively exaggerated by the manufacturers, and as long as the tyre is correctly seated the ranges are vastly greater than stated.
Example 1, the rims on my Kona Dew+ state they'll take a 28-42 - which is pretty wide ranging. I had 25s running on them for about six months and thousands of miles over last spring and summer with no problems at all.
Example 2, as an experiment, he ran his road rims on a touring frame with enormous balloon mountain bike slicks, must have been at least 50mm or so. Said they were a bugger to fit, but he commuted with them for several weeks and found it a hoot.
Example 1, the rims on my Kona Dew+ state they'll take a 28-42 - which is pretty wide ranging. I had 25s running on them for about six months and thousands of miles over last spring and summer with no problems at all.
Example 2, as an experiment, he ran his road rims on a touring frame with enormous balloon mountain bike slicks, must have been at least 50mm or so. Said they were a bugger to fit, but he commuted with them for several weeks and found it a hoot.
