Marathon Plus + SKS Mudguards = Oh no!

peat

After much cursing, I got my new Marathon Plus tyres fitted.

Front is fine. great.

Rear, well.....

The tyre must have a tadge more diameter than the tyres i took off. The M+ rubs on the bolts that secure the mudguards to the frame to the point that the wheel will not rotate. At all.

I removed the washers, but it is still nowhere near. Is there such a thing as an ultra-thin-domehead bolt??

Has anyone experience this and found a way around it?

MountainMonster

Is it the top of the bolt that is the problem? I.e. the area you use to screw it in is too long?

If you are bolting the mudguards to the inside of the hole, perhaps try the outboard side as this should alleviate any problems. If the bolt is too long then it is easy to source a shorter bolt.

fudgey

Pics will speak a thousand words. Get some up.

peat

Photo Time:

This is the tyre/guard as mounted:


This is sans wheel, that's an M5 button head I used (M4's supplied by SKS, M5 bosses on On One Pomino Frame). It rubs at both mounting postions.


Even when removing the bolts and taping/cable-tieing the guard, there is still rubbing that prevents the wheel rotating freely.

With the guard removed, this is the sort of clearance between the tyre and bosses:

The tyres are 28mm and don't seat quite true (the clearance varies on rotation by 1mm or so. But this frame should be able to take 33mm CX tyres, so I'm scratching my head a bit.

peat

My options as I see them:

- source fixings with lower head profile
- File down the lugs
- Find alternative mudguard fixing method
- swap 28mm tyres for 25's
- Return the Marathon Plus's and stick with the Vittoria Zaffiro's and put up with the odd puncture
- Extend the chain by 1 link (would that even work??)

desweller

Countersunk screw, maybe.

Otherwise look at drilling a couple of small holes in the mudguard and cable tying it to the brake bridge. Will need to think about paint wear and cable tie wear.

MountainMonster

That's a tricky one. I'm stumped, unfortunately.

Manc33

Peat wrote:

- swap 28mm tyres for 25's
- Return the Marathon Plus's and stick with the Vittoria Zaffiro's and put up with the odd puncture

You have M+ 28's on now? You can get the Marathon Plus in a 25.

I wish they did a 23. :twisted:

How many mm of thread is there on these long bolts?

djp66

Something like this may work, but I don't think you'll get anything thinner. Otherwise it is time to file down the lugs or go for the cable tie approach..



http://openbuildspartstore.com/low-profile-screws-m5/

peat

I think I will return the MP28's and pop the Zaffiro's back on for now.

I'm conflicted. I really wanted Marathon Plus as they are bullet proof and heavy. ideal for the minimum faff, tough going winter training that i'm using this bike for. But I also got this bike so I could run larger volume tyres for a bit of comfort.

My question therefore would be "Are 25mm MP's noticably harder/twitchier than 28mm's?"

fudgey

Hmm that is close.
Imo your options are to fit a thinner headed screw, or drill out the mudguard so it fits over the mounting lugthe use a thin head screw and a washer to hold the guard on. Maybe use an o-ring between the mount and guard to stop any rattle and rubbing.

and if that doesnt work file the mounting lug down but that would be my last resort.

Edit: you say even with no screw its still rubbing?
Is that around the screw area?

peat

Yeah, where the guard is just up against the thread boss, it still rubs slightly. Certainly enough to make me think that even a thin headed fixing would rub substantially too

The idea to oversize the hole to fit over the boss is a good idea though. I like the thinking, but as above, the fixing would still rub.

Also, the clearance is so tight on a clean/dry setup. I imagine the tiniest addition of water/grit would make a hell of a din.

Cheers

Peat

dj58

Have you tried a button head allen screw without the washer underneath?

https://www.boltdepot.com/Socket_products.aspx

fudgey

If you were to make the hole in the guard bigger you will loose the thickness of that, say 1.5mm. Combine that with a thin head screw and might gain 3mm say.

If you like, pm me your address and ill post you plastic push-in fasteners i use at work, they have a head thickness of about 1mm and are tougher than they look.

You will need to try them before you drill it out etc tho!

bendertherobot

Try Durano Plus 25c. You will lose about 1% puncture resistance (they are amazing), but gain comfort. The M+ can be a bit hose pipey to ride.

Manc33

Peat wrote:

My question therefore would be "Are 25mm MP's noticably harder/twitchier than 28mm's?"

I never tried 28's (25's are 2mm away on my rear fork) but I have my 25's pumped up to 110psi all the time and they seem to absorb shock alright even at that pressure. Don't forget the M+ has got 5mm of "stuff" around the tyre, so even a 23 M+ (if it existed) would be a more comfortable ride than a straight 23 race tyre with the pressure being equal. That "stuff" isn't at 110psi I know that much. They are strange things Marathon Plus.

The M+ to me looks like an all purpose tyre that would have no problems on bike trails (all those old railways that got changed into bike paths, or canal paths).

Cornering fast... I don't risk it. Its true that I don't feel as safe on them as I did on my stock 23's that came on my Triban 3 (and those were cheap).

The very best tyre would have to be a GP4000S I guess, because you need grip and the M+ just don't have it like a slick tyre does - if you don't care about punct*r*s that is. I am like you and think if I can get away with never fixing a puncture, why wouldn't I go down that route? I'm never racing. In fact I am never even in a hurry.

peat

I have GP4000's on my fancy bike and they are terrific.

The purpose of the steel singlespeed is for no nonsense winter miles/commuting around the mucky back roads of my locale. So, something that is heavy, hard work and minimum maintenance is what i'm after. hence the selection of M+'s.