6

My concern is that the actual one (700x23) is quite close to my brake (about 3 mm). It's safe for me to buy a 700x25 or 700x28? I would like to have a slightly wider tires.

the brake pads are touching only the rims

  • 3
    Depends on the shape of the tread and how well you keep your wheels trued. – Daniel R Hicks Feb 4 at 18:54
  • I added a picture, the rear brake is a little more tight. Do you think I have enough space for a different tire? Is the any way to check that dimension before buying?? – heracho Feb 4 at 19:24
  • 3
    Good work for changing that tyre - the picture shows a dry-rotted and cracked surface that could fail quickly, or could run fine for years. I'd change it asap. – Criggie Feb 4 at 20:20
  • Do note that your front and rear wheels don't have to wear the same size or even the same brand/model/style of tyre. I have a 25 on the front and a 28 barely squeaking into the back, with no chance of making the 28 fit in the front. – Criggie Feb 4 at 20:31
5

How much space do I need between my tire and brakes to change from 700x23 to 700x25 or 700x28 tires?

My understanding of the question is that you have 3mm between the top of the tire and the bottom of the brake using a 700x23 tire.
enter image description here

In the situation under question when going to a wider tire you need to worry about brake and frame / fork clearance.

In a perfect world you would have 1mm clearance on your brake if you installed a 700x25 tire. However, different tires may be slightly wider than 700x25 and some tires are a little out of round. So, it depends.
Also, we don't know how much frame clearance you have.

The only way to know for sure is to try the tire on your bike. Don't assume that if a tire works on the back it will work on the front - you have to check both. When clearance is tight it's important to test ride on the wider tires. Wheels will flex (some more than others) and the frame may flex so the tire may rub when riding (especially when pedaling hard) even if they don't rub on the bike stand.

How much space...

If the tires clear - all the way around (to clarify "clear" means your wheels rotate freely given frame/wheel flex and any riding condition, mud, asphalt you encounter) when riding - then all is good. There is no minimum amount of space needed if bicycle flex and environment are accounted for.

From experience, I was able to replace a 700x23 tire on the back with a 700x25, but not on the front. The front 700x25 tire cleared the brake but rubbed on the bottom of the fork crown.

A quick Google will tell you that there is a debate as to how much going from 23 to 25 matters and if the difference can be felt. Depending on your sensitivity it may not be worth changing.

It might be time to look into getting a bike designed to use wider tires. A test ride at your local bike shop would inform your thinking.

|improve this answer|||||
  • 1
    To be honest. I can't afford to change my bike right now, and I'm kind of fond at it. I need to change the tires anyway. It's seems that giving in the actual condition it's not a good idea to buy on amazon, but ratter go to a local shop where I could see the tire before buying it. – heracho Feb 4 at 20:09
  • 1
    @heracho Your local shop will be able to look at your bike and have a very good idea what will work. – David D Feb 4 at 20:18
  • 3
    There is a minimum space required - it has got to be enough to allow for frame flex without the tyre rubbing, so its more around the sides/shoulders of the tyre and less about the tread or rolling surface. – Criggie Feb 4 at 22:25
  • 1
    Agree with @Criggie - there's a minimum space required on the sides to allow for flex, but also along the "top" of the tire to allow for small rocks (or bits of new asphalt) to clear the gap without getting stuck between the tire and the brake arms. This may seem like a ridiculous edge case, but I've had at least two races where this directly affected the outcome (and ultimately led to the purchase of a new bike...). – Altom Feb 5 at 20:50
  • @altom What would the minimum space required for tire clearance be? – David D Feb 6 at 15:50
6

WRT the photo - I'd be quite confident you can fit a 25mm in there without issue.

A 28mm looks like it would probably fit acceptably, but I doubt a 32 mm would fit.

The best solution here is to take your bike to a Local Bike Shop, and buy your 28mm tyre/tube from there, on the provisio if it doesn't fit on either end you simply swap it for a 25mm.

Second option is to buy the tyre you want, and if it doesn't fit then sell it on ebay/local auction website, but you'll probably take a hit on the value.

Remember, you need to look at chainstay/seatstay clearances at the back, fork clearances at the front, and brake caliper clearances at both ends of the bike.


The other thing that may hold you back on tyre width is rim internal width. The wider tyres prefer to sit on wider rims. A 23mm tyre should be on a rim with a width of 13-17mm. A 28mm tyre wants to be on a rim from 15-21mm. More info at What is the maximum or minimum tire width I can fit on my bicycle Though do note these numbers are somewhat fuzzy edges.


Relevant thoughts - wider tyres do make it harder to drop the wheel through the brake pads. You may need to change your methods, by only inflating the tyre once the wheel is installed in the bike. Or you may have to look at how to get slack in your brake cable with a quick release or similar. Not a problem, but it can be frustrating to have to deflate a freshly inflated tyre to get the wheel through the brakes. More-so if you just used your last cartridge, or have to do it with a minipump (perhaps again!)

|improve this answer|||||
  • 2
    Many brakes have a quick release that opens them wider. The present brakes are single pivots. In my experience these are awful. I replace those immediately with decent brakes. A decent pair of Shimano dual pivot brakes (BR-451 or -4700) cost about as much as the set of tyres. And they come with new brake pads, which cost about a 1/3 of the brakes. – gschenk Feb 4 at 20:57
  • 1
    Obviously it would be best to take a pair of calipers and to measure the clearance, but I agree that clearance looks sufficient for 25mm tires on the current wheels. I suspect this is an older bike, and I believe those are likely to have more clearance than a lot of performance road bikes from the 1990s to late 2000s. – Weiwen Ng Feb 6 at 16:29
  • 1
    Addressing the point about fitting wider tires through the calipers, the OP may have a quick release on their levers. My wife's old 10-speed had this arrangement. Campagnolo Ergo levers for rim brakes have it also. – Weiwen Ng Feb 6 at 18:50
2

Your brake pads should not be touching your tires. If they are touching, you need to reposition the pads immediately so that they contact the rim sidewalls.

The only time this should be a concern is when you are installing or removing a wheel (when fixing a flat, for example). Brakes normally have a release that opens up the brake arms to accommodate the tire for this purpose—the release is either a small lever on the brake arms, or a pin on the brake levers. An extra 5 mm should not be a problem when the release is open.

If you are already riding around with the release open, use the brake's barrel adjuster to loosen the brakes so that the pads are correctly positioned with the release closed. If you need more adjustment than that, you'll need to loosen the cable fixing bolt on the brake arm and let some slack into the cable that way.

Another possible concern is that the larger tires will rub on your frame, although it would need to have extremely tight geometry for 5 mm to make a difference.

|improve this answer|||||
  • I added a picture, I think you are thinking on a different type of brakes. – heracho Feb 4 at 19:22
  • It looks like the poster is concerned about the brake arms touching the wheel, not the pads. – Ian MacDonald Feb 4 at 19:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.