Road Bike, Cycling Forums banner
1 - 13 of 13 Posts

·
Registered
Joined
·
132 Posts
Discussion Starter · #1 ·
Greetings,
Tomorrow I'll be picking up my second road bike, a 2009 Bianchi 928 with a full 105 groupset.
The bike comes stock with Continental ULTRA SPORT 700x23 tires and Mavic KYSRIUM Equipe wheels. My other bike is sporting Continental GP4000's 700x25. The Bianchi will be my new thoroughbred and ridden the most.

Should there be any issues with swapping these tires? My main concern is whether or not I'm going to run into any clearance issues putting the 25s on the Bianchi. (Different frame geometry, brakes, etc.) The GP4000s only have around 400 miles on them. Would you even swap the tires? Other than being an all-round better tire in general, I think the 25s at a lower tire pressure will provide me with a more comfortable ride. I'm 170lbs and I've been riding the GP4000s at around 110/105 and they provide a very comfortable ride. Thoughts?

Thanks,
- Bill
 

·
A wheelist
Joined
·
11,324 Posts
Why not swap the tires. 23 will be noticeably harsher than 25's. Try even lower pressures on the 25mm Contis. I'm your weight and have never used 110psi on a road bike (in 5 decades) and a pressure like that would jackhammer me. I use a lot more supple tire that you (Vittoria Open Corsa Evo CX 25mm) and use 80/90 psi. I believe in letting the tire work for me.
 

·
Registered
Joined
·
21,637 Posts
Have a look

BillyK said:
Should there be any issues with swapping these tires? My main concern is whether or not I'm going to run into any clearance issues putting the 25s on the Bianchi.
Look at how much clearance you have to the fork crown and rear brake bridge on the Bianchi with the 23mm tires. The 25 mm tires will take up about 2 mm more room (assuming both tires are honest sizes, which they may not be). You should be able to see the amount of space available. If there's room for the 25s on the new bike, there are zero issues with the swap.
 

·
Registered
Joined
·
132 Posts
Discussion Starter · #4 ·
Kerry Irons said:
Look at how much clearance you have to the fork crown and rear brake bridge on the Bianchi with the 23mm tires. The 25 mm tires will take up about 2 mm more room (assuming both tires are honest sizes, which they may not be). You should be able to see the amount of space available. If there's room for the 25s on the new bike, there are zero issues with the swap.

Thanks Kerry. Would you expect any road bike not to support a 25? I'm not 100% certain what the "fork crown" or "brake bridge" is, but I should be able to figure it out by visually looking at the bike. Being only a 2mm difference, I kind of assumed any road bike with a 23 would at least support a 25, but the LBS owner seemed to have doubts, so that's why I'm asking. I'll definitely ask him again when I pickup the bike as I'd really like to swap the tires if it's doable.
 

·
Cycling induced anoesis
Joined
·
13,006 Posts
You don't give any specifics about your other bike, but (assuming wheelsets are compatible) one quick and easy way to see if the Bianchi will accept the 25's is to swap your existing wheelset to the Bianchi.
 

·
Registered
Joined
·
132 Posts
Discussion Starter · #6 ·
PJ352 said:
You don't give any specifics about your other bike, but (assuming wheelsets are compatible) one quick and easy way to see if the Bianchi will accept the 25's is to swap your existing wheelset to the Bianchi.
The other rims are Mavic CXP22s and it's an SRAM/Apex group set. I've been trying to research around to see if anyone is running 25s on their Bianchi 928s but I'm not having much luck. I know that the frames were identical for 2008-2009, but they changed for 2010. (Infinito) The LBS owner should be able to confirm if 25s will fit. He seemed to be a big advocate of the 23s though. He claims that most everyone he rides with are using 23s. I really like my GP4000s and would like to swap them over. I guess I'll have to do a little more research. Tnx.
 

·
Cycling induced anoesis
Joined
·
13,006 Posts
BillyK said:
The other rims are Mavic CXP22s and it's an SRAM/Apex group set.
That wheelset should mount fine on the Bianchi, and for your purposes all you really need to do is mount the front wheel. If the 25c's clear the fork crown and blades, you'll likely be fine at the rear. Then just swap tires as you were planning.
 

·
Registered
Joined
·
132 Posts
Discussion Starter · #8 ·
PJ352 said:
That wheelset should mount fine on the Bianchi, and for your purposes all you really need to do is mount the front wheel. If the 25c's clear the fork crown and blades, you'll likely be fine at the rear. Then just swap tires as you were planning.

Thanks. I was wondering if a front fit would pretty much guarantee a rear fit. I'll keep you posted. Appreciate your input.
 

·
Registered
Joined
·
21,637 Posts
Tight clearance

BillyK said:
Thanks Kerry. Would you expect any road bike not to support a 25? I'm not 100% certain what the "fork crown" or "brake bridge" is, but I should be able to figure it out by visually looking at the bike. Being only a 2mm difference, I kind of assumed any road bike with a 23 would at least support a 25, but the LBS owner seemed to have doubts, so that's why I'm asking. I'll definitely ask him again when I pickup the bike as I'd really like to swap the tires if it's doable.
The brale bridge is the horizontal piece of tubing that your rear brake is mounted on. Some frames have a different rear end configuration, but generally the brake bridge refers to the rear of the bike. The fork crown is the arch of the front fork, also where the brake is mounted.

Unfortunately, there are actually road bikes out there which will have very tight clearance for a 25 mm tire, or maybe even rub on a 25. Why this is deemed a good idea by frame designers is a whole other discussion.
 

·
Adventure Seeker
Joined
·
5,115 Posts
I had a pair of Ultra Sport tires. I will never buy them again. The GP4000's are way, way better tires. I couldn't avoid pinch flats or puncture flats with those Ultra Sports.
 

·
What the what???
Joined
·
12,922 Posts
Kerry Irons said:
Unfortunately, there are actually road bikes out there which will have very tight clearance for a 25 mm tire, or maybe even rub on a 25. Why this is deemed a good idea by frame designers is a whole other discussion.
Too true. I swapped the 23s on my Speedster with a set of Krylion 25s. Honestly, I never bothered to look at clearance. I just assumed they'd fit fine. I'm glad I didn't buy a set of 28s. The 25s barely fit.
 

·
Registered
Joined
·
132 Posts
Discussion Starter · #12 ·
I finally got around to swapping the back tire. After mounting the GP4000 25 tire on the new wheel, I wasn't comfortable with the clearance on the Bianchi. Even with the stock 23 there's not a ton of clearance. I have to tell you though, these GP4000 tires are MUCH EASIER to work with than these Ultra Sports. The 4000's seem to be a lot more pliable and much easier to manipulate when changing. I had to battle with the Ultra Sports for a bit before I could get them mounted. I need to stop by my LBS this week for a fit so I think I'm going to ask them to toss on some GP4000 23s.

I have another question. While I had the Bianchi upside down changing out the tire, I noticed a small screw on the floor. I'm not sure if it's anything important, or even if it fell off the Bianchi, but it has me a bit concerned. I did a quick once over of the components to see if it looked like any screws were missing, but the only thing I noticed was this small hole under the 105 RD. I'm not even certain if the hole is threaded and I confirmed that the screw wouldn't go in. First of all, here's the screw:



Here's the RD hole:



For those of you that are intimate with the 105 groupset, do you think this screw goes to anything? I plan to bring it to my LBS this week and have them check it out just to make sure.

Thanks,
- Bill
 

·
Registered
Joined
·
132 Posts
Discussion Starter · #13 ·
Mystery solved. When I turned my bike upside down, my Bontrager CO2 dispenser fell out of my bag onto the floor and the screw came out of the valve. I've reattached the valve with the screw and everything is good. Is that little hole under the RD normal for the 105? Sorry for the false alarm. :)
 
1 - 13 of 13 Posts
Top