I have a 2021 Cannondale Topstone Ultegra. Cannondale lists the max tire size as 40mm for 700c, 45mm for 650b. I have 40s on there right now, I’m not worried about the front having clearance. But in the rear, I would really like to be able to put a wider tire if it will fit realistically and safely.
Going 650b is expensive and changes the nature of the bike. I’ve tried to capture in the photos about how much clearance there is with the tip of a number two pencil stuck in there. It is about 3 to 4 mm on each side at the narrowest. I think with running lower pressures, a 44 might be too wide, but does anyone think a 42 will safely fit in there? I know there needs to be some clearance for mud buildup, but it seems like Cannondale is being a little bit too lawyery by saying 40mm max.
Does anyone have this bike running a wider rear tire? Or does anyone else have experience with recommendations versus what you can actually get away with? Thanks in advance for any information
by HolidayWarm5971
3 Comments
Looking at the photo, I don’t think Cannondale is being lawyery by saying 40mm max, that clearance already looks super tight, tighter than I’d want to run given that you run the risk of mud and debris building up in there. You wouldn’t notice much of a difference between 40 and 42 anyway.
You’ll reap more benefit from supple tyres set up tubeless and at the correct pressure, maybe some tyre inserts to allow you to run lower pressures.
There is always a little flex in wheels and tires when cornering. Always leave a little more clearance than you think you’ll need when looking at the bike in the rack.
Also, tires measure out different between brands (and wheelsets). I’d suggest you get a cheap calipers and measure your tires to see what the actual width is.
Measure your tires and see what they are actually inflating out to. It will be different for each rim.
Also, they are required to spec the bike with 6mm of clearance in every direction. Its the law.
Lastly, I wouldn’t go bigger than this with another knobby tire. You could however try a slick, something like the Rene Herse 44 or the Panaracer Gravelking slick in the 43.