I am looking for a new pair of wheels for my son’s race bike (Guerciotti E-740 Disc).
The current wheels have an internal rim width of 19 mm and are optimised for 25 mm tires.
For the new wheels, I have the following inner rim width options:
18 mm - 21 mm - 23 mm
I would prefer a wider inner width (because his future bikes will certainly have clearence for wider tires), but I am not sure that this will fit the current frame.
Here is a picture of tire clearance on the current frame (25 mm tires on a 19mm inner width rim).
Do you think moving up to 21mm or even 23 mm would cause a problem with this frame (tire would than have to be a 28mm, off course).
I’m presuming this is the same son mentioned in a post re the front derailleur Mount? If he’s 10, he’s light and he’s not going to be pumping out power compared to an adult.
Therefore, I’d guess that the lightest combination of options would be the most advantageous in terms of his power overcoming his and the system weight of the bike.
Also, given that weight, the grip in a 25mm tyre will, in relative terms be far greater than an adult would get in 30mm tyres.
That is correct, but the difference in weight between 19mm and 21 mm internal width is very minimal.
I would like to be able to use the wheels for a couple of years. They outgrow these bikes quite fast, and every ‘new’ bike usually comes with heavy wheels.
That’s why I would prefer the 21mm version instead of the 18 mm version. The current trend towards wider tires will make 18mm obsolete quickly, I’m afraid.
But my question is (given the clearance you see on the pictures): will rims that are 2 mm wider internally, in combination with a 28 mm tire, will be too wide for this frame?
Putting the 25mm tires on 21 mm frame might also work, but I don’t think this is recommended.
As part of a BRR test of different rim widths, “the width of the road bike tires increases by 0.425 mm per mm increase in rim width while the height of the tires hardly changes”.
If you have a 28 lying around, you could measure the width on your current rims and add the .425 * rim width difference. The 28 will most likely be taller, so something else to consider
Yeah +1 to previous post. Try some 28s and then see if you have more room to play around with. Obviously tires are a smaller investment than wheels. If the 28s are maxing out the clearance with the 19mm rims, nothing wrong with running that combo.
Prett sure 25c tyre on 21mm hooked rim is within ETRTO, just. Even if just outside, likely fine bearing in mind the smaller person that will be on the bike means lower pressures.
Couple things. That current rim & wheel set up looks very close to maxing out the frame. You could throw a wider tire on the current rim and see what that fits like. Even at his age you will have the possibility of the rim loading up and potentialy rubbing on the frame.
Another option is to fit a wider rim & tire combo on there if you have another set laying about.
A wider tire is also going to be a taller tire as was mentioned above.
If you can find the specs for the bike, that might tell you what the largest tire that will fit, or reach out to the vendor.
Personally I think you might have to wait a year or so. It is tough I know, my 2 kids are finally almost full grown and I was buying bikes and skiis almost yearly.
I have installed a new pair of 28mm Conti GP5000 tires on the current wheels yesterday, and there is still some clearance left. So let’s go for 21mm inner width.
