Originally Posted by
tedder987
@
Wilmingtech that brings me full circle back to the initial question. Is a wheel with a 25mm internal width going to work OK on a road disc bike (Spz Roubaix) that nominally is rated for 32mm tires,
With the 25mm internal width, typically you'll add about 2-3 mm to the marketed tire size. So a 28 would inflate to 30mm. This is dependent on tire manufacturer but 2-3mm is typical.
or is it going to let a 32 get too wide for the bike, while being too wide to comfortably run a (nominal) 28mm tire which will fit the frame?
You wont wont to run a 32 on a rim with 25mm internal width if 32mm is the max specd tire size for the bike. Stick with a 28mm. It will inflate to 30mm and match the width of the rim. A 25mm would inflate close to 28 for a slight aero benefit.
With the current wheels (28/32 GP5000) I have ~1cm sides & top at the forks. At the back the tightest is at the side, 3.2mm to the chainstay (digital vernier calipers) with 9mm to the bottom bracket in the middle and more space yet at the seat stays.
In the front, 1cm is plenty of space. You can leave the 28 on there and it will inflate to 30-31mm and you'll get a cush ride and it will be within spec. Drop to 25mm if your on smooth tarmac for the day.
On the rear drop to 30 and you should be fine. Itll round out to about a 32mm width. You might be better off going 25/28 on tarmac and 28/30 on gravel with the wider rims. The rim at its widest point is 30mm so as long as you have 36mm of clearance between the chain stays at the top ot the rim in the back you should be fine. You can shoot an email to Andy
andy@hedcycling.com
and ask him about the fit on a Roubaix. They are pretty quick to reply or call them at 888-246-3639.
What bike and tires do you run your emporia's on for reference btw? Is it a road bike or gravel with wider clearances?
They are currently on a Blue Prosecco which is more of a disc brake endurance bike than a true gravel bike. With 32mm Vittoria Terreno tires on the HEDs they inflate to 35mm and theres not much room for more than that.
I'll take some measurements tomorrow if you like. I am currently running conti sport 28 road tires on these rims and Im pretty sure they measure out to 30mm.