exwoll

So, yesterday my new 700x25c Schwalbe Marathon Plus tires arrived, something that I was waiting for a long time, since they aren't sold in my country and the only tires I can get here for my bike are racing ones that get 2 punctures/day.....and I use the bike for everyday stuff, with no other weights than a light backpack.

They were a lot easier to fit to the rim than some reviews said . The front wheel fitted perfectly, looked great!

However, I encountered an issue with the rear one... it was touching the rear part of the bike frame (which is a little deformed and enlarged for aerodynamics) as you can see in this image:

My options were to modify the frame itself:

1. Apply some sandpaper and wear a little bit the frame so the wheel can turn freely.
2. Dent the frame a little bit with a small hammer (really risky option)
3. Wear the tire itself to get that 0.5-1mm

Then I thought about lowering the wheel in the dropouts, since the axle is quite thin and I can safely lower them a couple mm without risking the horizontal stability of the wheel.
The bike has old vertical dropouts and the wheel is holded by a quickrelease.

This "solution" looks fine and solid if tighten the grip of the release enough, and the only risk would be the wheel falling into the dropout in some bump in case the release gets whobby with time.....
Any ideas or suggestions with this issue?

Ps. Pls dont tell me "go buy another tires/bike" because Im not in a good financial situation right now to afford any of those.

would like to add some pics, but the forum doesnt let me upload anything -.- (if anyone can receive the pictures via pm and post them here would be great )

WizardOfBoz

New guys can't post pics until they have ten posts. A hassle. I think that if you upload the picture to something like imgur or googlepics you can post the URL here and someone can look it up.

One question is about why/how exactly is your bicycle rear "a little deformed and enlarged for aerodynamics"?

Another question is where is the tire hitting? It sounds like it's hitting the brake/fender bridge between the seat stays. Or is it hitting the seat tube?

Anyway, it sounds like there's no other option, so that's the option you use.
It might be that you could cut and file a little piece of metal in a crescent moon shape to put (glue?) in the dropout. Like the piece in this picture (but without the threaded stud).
Or you can google "rear bicycle dropout frame spacer" and there's a few ideas.

ramzilla

Dremel tools with metal grinder bits are nice for adjusting metal things. But, if there's enough room in the dropouts to move the wheel back then no worries.

billridesbikes

“Lowering the wheel in the dropouts”?

Do you have horizontal dropouts like a track bike (Like the picture from WizardofBoz) or do you have road bike dropouts that are vertical?

_ForceD_

I know you want to use the new tires...and I wouldn't modify the frame in the ways you've suggested...but my suggestion is to continue to use the skinnier tires, and get some puncture resistant tire liners to help prevent all the flats you get.

Dan

HillRider

It's not what you want to hear but I have to conclude you bought the wrong tires for the wrong bike. If "the rear part of the bike frame (which is a little deformed and enlarged for aerodynamics)" is really indented to shelter the rear wheel then you have a Triathlon or time trial frame which is meant to be used with thinner more aerodynamic tires and the 25 mm Marathons aren't them. Are the marathons available in a 700-23 version?

exwoll

Its hitting the tube
Here is the frame: h ttps:// i.imgur.com/a8p54Kw.png
Here is the exact spot where the tire is touching the frame (which slows them down): h ttp s:// imgur.com/6i1cYqR
And here is the droupout: h ttp :// i.imgur.com/40d7nXn.png

Oh boy, I tried every possible solution, nothing works with the punctures, I was getting 2 every day some months, was a hell :/.

I couldnt find any vendor that had the 700x23 one :/. I tried a regular 25mm tire from a friend and it fitted with no problems (besides the smaller space between the wheel and the frame), but it resulted that the 25mm marathon plus had extra antipuncture padding, which added some mm to the tire height, so it didnt fit because of that. If I had ordered the regular Marathon ones, I wouldnt had this issue :/. I cant send the tires back, nor I have any vendor for them in my country to get others quickly, and a friend got this ones on his way back from the states, so I dont know when ill be able to get new ones (if I ever see the 23 variant in stock)

I tried lowering the axle a couple mm, which gave me like 1-2 mm of free space for the wheel, just arrived from the test drive, and it holded up well, taking in count all the bumps I went trough in these 15km .

tyrion

I'd say go ahead and lower it by a couple mm, but I think braking might tend to slam it back in. Maybe after a some tire wear you won't need to lower it. Also, see if you can get away with lower tire pressure.

Here are your photos:

exwoll

It worked fine at around 50-60psi, but I felt that it was too low for the tire, so I pumped it up to 80 and it started touching the tube as shown in the pictures. The roads here are VERY random, so riding with rock solid tires is impossible if you dont want to get a new lower back after a couple months lol (old bumpy asphalt, bad placed or old concrete tiles/plates, weird bumps and gravel patches... only the tiles make you feel like inside a cocktail shaker) so I never go above 80, usually just leave them by when I feel they are hard enough to squeeze with my hand.

Oh, and thanks for the pics kind internet stranger! :3

ctak

Unless you weigh under 130-lbs, 80psi is too low: https://www.schwalbetires.com/tech_i...ation_pressure

blamester

What's under the tape?
Remove it.

guy153

The clamping force on the nuts is strong enough to hold the wheel where it is supposed to be, but the kind of dropouts you're supposed to do that with are longer. These are tiny and so if the axle isn't properly seated in them I'd be a bit worried it wasn't gripped properly.

I don't think you should modify the frame especially as it's made of Aluminium so won't take kindly to it.

I guess an outside option would be to change the rear rim for a 650B, but you would probably also need a new rear brake caliper, and obviously a new tyre, but you could keep the 700C one as a spare for the front.

canklecat

Check your rim tape/strip and tube. Thinner rim tape/strip and lighter weight tube might help it fit better.

If it's that generic rubber band rim strip, that's about as thin as it gets. The only thinner stuff is something like the firm plastic high pressure rim strips from Schwalbe. Before buying more rim strips, you might try a single layer of duct tape. See if it reduces the outer diameter of the inflated tire.

The thinnest butyl tube I've used that doesn't cost more than regular tubes is Continental Race 28 Light. While they seem thin and flimsy, I've had no punctures with these so far after several months. But I don't get many punctures at all, and I just ride inexpensive Continental Ultra Sport II, which have no puncture shield, and Conti Grand Prix Classic skinwalls, which do have a thin puncture shield. Lots of broken glass and debris in my area, but I guess I'm just lucky, or manage to dodge it.

You wouldn't think a thinner rim strip and tube would matter, but right now there's a slight bulge in the Conti GP Classic I mounted Sunday night on my steel bike's rear wheel. That slight bulge in one spot that just barely touches the bottom of the rear brake bridge. That's never happened before with this tire on either of my road bikes, both of which were from the era when racers used 700x18, and 700x23 was considered "fat". But this time I used a thicker, heavyweight butyl tube and it had a thick patch from a previous puncture. That's just enough additional material to cause a very slight bulge in one spot. So later this week I'll switch back to the Conti Race 28 Light. And I prefer Lezyne glueless patches -- they're paper thin and work just as well. No clearance problems with tight rims.

And if your budget is as tight as mine, try Continental Ultra Sport II. They're really good for such cheap tires. For awhile I used 'em with Slime sealant in the tubes, but it wasn't necessary. I've had one puncture in two years with two sets of Conti Ultra Sport II, and the sealant didn't even help. So I ditched that tube and just use regular tubes.

WizardOfBoz

This.

The added material on the frame that is of very questionable, low value in streamlining the bike. Especially given that there's a fender! Remove the blob of tape, adjust the fender, and you'll have space for the tire. If you feel you must redo the tape thing, add it in a way that doesn't interfere with the fender and wheel spacing.

The vertical dropouts you have don't have enough length to support moving the axle much and you're only moving the wheel in sin(90-74°) mm for every mm you drop the axle. That is, to get 1mm clearance you need to drop the axle 4mm. You don't have 4mm of dropout length to play with.

Wilfred Laurier

If I recall correctly, there are images of the marathon tires showing a cutaway cross section, and these images show that the flat protective strip adds several millimeters of height. Other flat resistant tires use different strategies that do not add so much height. It might be a bit of a pain to source other tires depending on where you are, but there are tires out there that will work.

Also, I don't think trying to clamp your QR with the axle not fully seated is a good idea, especially with the basic 'open cam' type quick release you have - these do not provide much clamping force.

exwoll

I used a regular electrical tape, which is quite thin, to cover the color of the bike, since I don't really like the shiny sporty yellow patches it have. In one of the pictures its removed, it only adds like 0.01mm, since its only one pass

Yup, and the Marathon Plus adds quite a lot to it, I read that it was some 3-5mm.. sadly I only checked that info once I found the problem with the fitting :/

I actually tried lowering the axle yesterday by like 2mm (the axle is quite thin, and I also checked that it doesnt end up hanging partially from the dropout), and it gave me the same clearance with the tube. I did a 15km test ride in the city through all the ****ty roads we have here, and it holded quite well (dropped once, but I adjusted the QR tighter and it holded like a champ). The clearance between the wheel and the tube is now around 2mm, but works quite nicely .

Also I found out that there is this kind of adapter for single speed conversion, which I would probably have to fabricate myself: http s:// i.pinimg.com/originals/9a/f8/59/9af859a3f38ef0accc5cc0d1616b9cf4.jpg
Dont know how good will that help me but seems a quite simple and effective solution to my dilemma!

Thing is that that roads here are like this; http s:// elchacoinforma.com/wp-content/uploads/2019/08/Enlosetado-6.jpg
And that picture is from some nice area, usually its all badly placed with a lot of pointy ends everywhere which makes riding at 100psi a literal torture and probably very harmful to your back :/

I will check this! I used a slice of an old tube I had which is quite thick, but I'll try with a couple layers of electrical tape, or maybe some zoedo "antipuncture" tape I have somewhere!

squirtdad

as noted before...unless that "aerodynamic" bulge can be removed you simply have too big of tire for the frame, especially as the rear dropout is vertical (i.e no way to move wheel back)

Riding low pressure on bumpy roads is a recipe for pinch flats

I under stand budgets and kludge with the best, but in this case, unless the bulge is an add on and can be removed, I think you are dead in the water..... you would need to move to 23mm or even smaller which will then give you ride issues.

WizardOfBoz

MarcusT

Schwalbe are notorious foe being slightly bigger than labelled size. I have had to return Marathons, Nobby Nics, Jumbo Jims because that 10mm bigger was too much for my frames
I say return the tires. Why damage your bike, when there are dozens of other tires out there?
If finances are a problem, see if you can sell the Marathons for a discounted price and take a $10 hit for something more affordable

tyrion

It sounds to me like you could let some pressure out and be more comfortable.

billridesbikes

This is a very interesting discussion, but the easiest and simplest thing to do is ride it at the lower pressure where it doesn’t rub the frame and is seated correctly in the drops. If this comes to 60psi on your tire gauge this is probably OK especially if you’re not a very heavy rider.

Here is a tire inflation chart. I think you should regard these tires as larger than 25s, they are probably closer to at least 28s or bigger.

Taken from William Benedict’s tire inflation article. x is load per wheel, and the rear wheel supports 55-60% of the rider weight. 60psi might render you slightly under inflated wrt to this, but maybe not significantly that you will have problems.

aggiegrads

If you are only need a fraction of an inch, I would take a belt sander to the tread of the tire while someone else turns the back wheel. Don’t go nuts or you will go to the breaker layer.

The tread on the marathons is tough as hell, and you will still get a lot of mileage out of the tires.

Amt0571

This tire is not suitable for your frame. Period.

Even if wearing the tire or damaging the frame allowed it to fit (which I have to admit sounds totally mad to me), the clearance would be so tight that I wouldn't be comfortable riding that bike. Tires, frames, and wheels flex when riding, and you don't want an unexpected sudden stop when going over a bump or taking a corner because something moved a little bit and your tire unexpectedly made contact with your frame.

Trakhak

I'd think of it this way: your bike is designed to ride optimally with tires that fit it properly. Honor that design objective by installing the appropriate tires.

thehammerdog

smaller tires
new frame
wider rims.