Minimum Tire Clearance on a road bike?
 

I got a used merlin road bike and had the shop switch to 700x25 armadillo all weather tires. I kinda wanted 28s but they talked me out of it which was good but not for the reason they said. I think I have less then a millimeter of clearance on the top of the tires.

I literally can't fit 8 1inch wide pieces of newspaper in between the rear tire and where the brake mounts. On the front there is a bit more room between the top of the tire and the fork. When I removed the tire today to do a post first commute check I found everywhere a little dirtied up except right under the tire most likely because dirt wouldn't fit in there.

Is this too little room? I'd thinks so but this is my first road bike so perhaps no. This is a bike I want to last a good long while.

No rub? it's good... works like a tire saver (knocks off large pic-n-ups from the road)

Thanks. No noticeable rub. Just a light pedal and the wheel spins smoothly for a very long time.

The only problem could be if you rode through some real mud and the tire bound in the brake caliper causing a very sudden stop. On the road that's pretty unlikely but I'd avoid mud puddles anyway. :)

As you now know, most sports bike frames are designed around 700x23 tires. Some 700x25's may fit but those running true to size or a bit over are going to be a very snug fit. The Armadillos have a thick tread and sidewall so they are about as big as a "25" is going to get.

A mm of space on the rear brake bridge??? I am riding a Conti Contact 28 and have about 3 to 4 mm space on the front and rear-tire-to-frame spacing. Sounds like the brake bridge might be a little too low. Contact Merlin and ask them. I get the same spacing on 3 of my other frames with little variation. Something doesn't sound right.

Don't break a spoke or get a bulge in the tyre...

People have been hurt, even killed, when a small stone or bit of debris gets wedged between the tire and the fork. For optimal safety, you need a TON of clearance. The semi-loved Schwinn Varsity was one of the best designed bikes in that regard. It had room for 32 mm tires, PLUS fenders, and still had lots of open space for mud and rood debris.

The only current road bike designer that puts a high priority on that sort of fork clearance is Rivendell. Their WORST fork will fit 32mm tires with lots of clearance left over. And, of course, well designed touring bikes and cyclocloss bikes have lots of clearance.

I sent a note to merlin about the rear but I think their answer will be get a smaller tire or send it to use with $$$ and we can move it up *shrug* not sure what else they could do.
In the front I have about the same space my wife does on her fuji road bike so hopefully that isn't a problem.
I may get a different set of tires to see if they make that much of a difference but from what I have read the newer armadillo especially are really tall.

For what it's worth, this guy is having problems with the rear, not front. Those sorts of catastrophic accidents generally occur on the front.

Yeh, I was going to say: it's not a big deal as long as you have clearance at your front tire.

If a stone happens to wedge between the bridge and rear tire, your rear wheel will lock up and you come to a stop. If a stone wedges between your front fork and tire, you go over the handlebars.

I think the minimal tire clearance in back should stop anything from wedging in there but I may step down to 23s next set. The brakes in the rear barely have any more clearance. Actually if I remember correctly I had to loosen and retighten the rear brake because somehow it was tightened cockeyed onto the washer and was actually rubbing the tire.
Soo I learned don't buy a bike and have them swap old rotted tires out after closing they might be in a rush :rolleyes: Well I hope they were in a rush otherwise they didn't notice a tire rubbing the brakes to bad it wouldn't roll. Mind you they told me it was an older 8 speed when it was a 9 speed but hey all the cheaper for me :D