Road Bike, Cycling Forums banner
1 - 18 of 18 Posts

· Banned
Joined
·
270 Posts
Discussion Starter · #1 ·
I just tried 25mm tires for the first time (conti GP4000) . When I got home from my first ride on them I realized I mounted them with 23mm tubes I always use . Should I have gotten size specific tubes (25mm) ??? I rode over 40 miles with these tubes , did I get lucky ? Or is there no need for a 25mm tube ??

I really like 25mm . I don't seem any slower and there is a much smoother ride . I don't race ( or get over 25 miles an hour for that matter ) , so I believe I found my new tire width ...

 

· limit screwed
Joined
·
807 Posts
Just curious...can you measure your GP4Ks with a caliper to find the true width? My 23s seem to be more on the 21mm side of things...
 

· Registered
Joined
·
863 Posts
weiwentg said:
I've been running 18-23 tubes with 30mm cross tires. nothing has exploded yet. you should be fine running the above tubes with 25mm tires. don't Contis run slightly narrow anyway?
I use 26 inch mountain bike tubes on my 29er. Rubber expands fine. Granted it expands to a larger diameter better than a larger width, but still anything within reason shouldn't worry you.
 

· Registered
Joined
·
21,832 Posts
Seem to be?

MaestroXC said:
Just curious...can you measure your GP4Ks with a caliper to find the true width? My 23s seem to be more on the 21mm side of things...
How can something seem to be a given size? Either it is or it isn't. Is there some alternative to measuring that you're keeping to yourself? :) For me, Conti GP3K and GP4K have both always been 23.0 mm.
 

· sometimereader
Joined
·
1,202 Posts
PinarelloFan said:
I just tried 25mm tires for the first time (conti GP4000) . When I got home from my first ride on them I realized I mounted them with 23mm tubes I always use . Should I have gotten size specific tubes (25mm) ??? I rode over 40 miles with these tubes , did I get lucky ? Or is there no need for a 25mm tube ??
Using a given sized tube on a larger cross section tire means that the tube will have to expand more when inflated. That results in a slightly thinner layer covering the high pressure air. So perhaps you give up a bit of flat protection. How often does a glass sliver, thorn, etc. only partially penetrate the tube?

For 23 to 25, I'm suspect you'd never notice the difference caused by a slightly undersized tube. 23 to 28 is probably ok too. 23 to 32 might be pushing your luck.
 

· Registered
Joined
·
772 Posts
I recently replaced some tires and tubes for a co-worker who had been riding with the original factory equipment for 15 years. The tires were worn to the threads but she had never had a flat. When I got into the 38mm tire, I found Trek had been using tubes rated for 23mm. I would agree there is some room for tolerance.
 

· Two scoops of inertia.
Joined
·
530 Posts
PinarelloFan said:
I really like 25mm . I don't seem any slower and there is a much smoother ride . I don't race ( or get over 25 miles an hour for that matter ) , so I believe I found my new tire width ...
[/URL]

There was a thread on this somewhere, but I switched my front to 23c and I noticed the bike is a lot easier to handle with the narrower steering tire. It's violence upon the hands, but I can brace for that. Tire size made more of a difference than I anticipated. That frame is killer by the way.
 
Joined
·
1,130 Posts
25s are great -- 28s are better

Like the OP, I was suprised at the difference in the ride when I went from 23s to 25s.

I saw no downside -- only more comfort and a better grip on the road.

Now on 28s (though they don't pump up that big -- more like 26.5). Love 'em.
 

· Registered
Joined
·
988 Posts
Don't worry about the tubes in there - you could always carry spare 25 tubes and switch when yu get a flat.

I used Ultra gator 25's on my steel nag and loved the ride and decided to use same for a new build I was doing eventhough it wasn't appropriate for the bikes racing pedigree and found it to be somewhat sluggish - will have to switch back to 23 on that bike to see if things change.
 
1 - 18 of 18 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top