johngwheeler

I'm test riding a loaner Fuji Gran Fondo (2015 model 2.7, rim brakes), which has 25mm Vittoria tires fitted.

I'd like to try 28mm tires - Conti GP 4000 IIs - but wonder whether the frame / fork clearance is going to be enough, particularly as I have heard that the Contis can inflate to somewhat more than 28mm. It looks a bit tight!

Does anyone know whether any brand of 28mm tires will fit, in particular the GP4000?

Thanks!

Maelochs

I have no idea about much of anything ... but I know I have a Fuji Sportif with 28s and ample room for more ... Hang on and let me look .... Yeah, I bet it would take 38s.

Now, I have a Sportif ... don't know if that is the same frame as the Grand Fondo. Can you borrow a wheel to test ... or borrow a 28-mm tires and put it on the existing wheel? Or just find a piece of wood, whittle it down to three mm, and slide it between the frame and tire at all the stays.

One of the reasons I got the Sportif was because I would use it as a gravel bike, light touring bike, grocery bike, or just a bike to ride. I love it.

https://www.bikerumor.com/2016/03/01/123055 says the bike fits 28s.

"If you plan on sitting in the saddle for more than ten hours per week you should consider moving up to a Fuji Gran Fondo. These are lighter, smoother due to the carbon fiber frames, and get longer service life from upgraded componentry."

https://www.fujibikes.com/granfondo/ this site also says it takes 28s (it ids the Fuji site.)

johngwheeler

Thanks for the reply.

Which year is your Fuji Sportif, and does it have disk or rim brakes? I get the impression that the 2016 models may have wider clearances, particularly the disk-brake models.

I'm assuming the Gran Fondo geometry is the same as the Sportif, but there is no way on my 2015 Gran Fondo that anything more than 30mm would fit in the front.

I did read a thread in which one person complained he couldn't fit a 28mm Conti GP 4000 in the rear because it fouled the seat stay bridge, but this may have been an older model.

I'll try to measure it as you suggest.

John

johngwheeler

I went and had a look at my bike in more details and it's not good news for 28mm tires....

They might fit at the front, where there's about 5-6mm clearance from the top of the tire side to the fork crown:

Frame-07-07-2017-03-03-39.jpg

...but at the rear, the seat stays converge to to an arch that is only about 2-3mm above the 25mm tire, clearance to chain stays is about 5mm:

IMG_2522.jpg

Given that Continental GP 4000s have are generally considered to be wider than measured on most rims (I've seen reviews that show the 28mm inflates to 31mm on 17C rims), that would mean up to a 6mm difference in total height (assuming width & height grow in proportion) or 3mm higher under the seat. That would almost certainly not fit.

Bummer....I may try to swap the 28mm Contis for 25mm (which may expand to 27mm according to review), which would probably be OK.

deapee

see this thread:
https://www.bikeforums.net/general-cycling-discussion/1074978-tire-fit-annoyance-advice-please.html

redlude97

I've ridden with less clearance, its fine.

johngwheeler

The photos are with the current Vittoria 25mm tires. I was trying to fit 28mm GP4000 - I very much doubt they will fit in the rear and at least one person with a similar bike (see thread link in one of the replies) has tried exactly this.

johngwheeler

Thanks; I found this one too. Exactly my situation, and I think I have my answer: 28mm Conti GP4000 will not fit in the rear.

Now what to do with the 28mm Contis I've bought? Send them back (to the UK from Australia :-( ) or put on another set of wheels?

redlude97

ah, that wasn't clear from the post. YMMV but people have gotten away with shimming the rear dropout if there is clearance on the side but not the top of the brake bridge.

johngwheeler

How would this work? Wouldn't a shim on the dropout just open up the chain stays a bit? I don't see how this would affect the height of the brake bridge above the tire. I don't understand where the shim would be fitted.

In any case, it's no biggie - I doubt I will hang onto this bike for very long as it's also a bit large for me . It's really just a long term trial at low cost to me, so that I can experiment with a road bike.

redlude97

a shim on the internal part of the dropout where is touches the axle, to effectively move the wheel vertically down.

johngwheeler

I see. I'm not sure this is something I'd really want to mess around with unless I absolutely *had* to have larger tires on this bike. I have other bikes with lots of clearance, so I'll probably just find a good 25mm tire that fits (could go to 26-27mm inflated width probably) for this bike. Thanks for the suggestion anyway!

johngwheeler

Turns out that the 28mm Conti GP4000S II wouldn't fit reliably at the front either. I had tried it at 80psi, but when pumped to a more normal 90-95psi it starting rubbing at the fork crown (zero clearance), so this is clearly a no-go.

Looks like I'll go back to the 25mm and that's my limit for this bike.