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700c - 23mm -> 25mm tyre fitting trouble



 
 
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  #1  
Old January 18th 05, 05:28 PM
Webbo73
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Default 700c - 23mm -> 25mm tyre fitting trouble

Hi all - I'm ashamed to ask for help on this, but...

after reading about good puncture-resistant tyres for commuting, I
decided to replace the maxxis default 23mm tyres on my Ridgeback
Genesis Day 0 from a couple of years ago to some Schwalbe Marathon
Pluses... I managed to find a 25mm pair of these and assumed (perhaps
wrongly) that I could go from 23mm to 25mm on the same rims with no
problems.

I don't have the exact rim model no. to hand, but the current
equivalent model has Alex RP-15 32h and I know that mine are also
Alex, so am assuming they're the same or very similar.

The maxxis "hors categorie" tyres that came off were a soft compound
that was relatively easy to take on and off - the Schwalbes are a lot
more rigid and look almost flattened when not on the rim (i.e. the
inner diameter that should sit in the rim is splayed outwards). It
takes quite a lot of force to squeeze them into shape - so much so,
that when trying to fit them onto the rim, I can't get more than about
15cm's around before something pops out - quite often on the other
side of the rim. Now, I may be no expert, but I've changed a variety
of tyres over the years but never been stuck like this.

I didn't think a 2mm difference in tyre size would cause me a problem
- but I don't know what else to try - maybe another pair of hands
might help, but that's not much use to me if I get a puncture on the
way home one night! I even tried the tyre without the inner tube with
no joy so the only thing I haven't tried is to use the inflation of
the inner tube to try and make the tyre more into the correct shape to
fit onto the rim (as I say, at the moment, it is very splayed out). I
did partially inflate it when I first tried to put it on, but I
thought that was just to avoid getting pinch flats. Perhaps I need to
go a bit further, but then I'm not sure if I'd be able to push it over
the rim.

If anyone has any tips or experience with this rim / tyre combo, I'd
be very grateful to hear from you!!

mike
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  #2  
Old January 18th 05, 05:54 PM
David Martin
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Posts: n/a
Default

On 18/1/05 4:28 pm, in article
, "Webbo73"
wrote:


The maxxis "hors categorie" tyres that came off were a soft compound
that was relatively easy to take on and off - the Schwalbes are a lot
more rigid and look almost flattened when not on the rim (i.e. the
inner diameter that should sit in the rim is splayed outwards). It
takes quite a lot of force to squeeze them into shape - so much so,
that when trying to fit them onto the rim, I can't get more than about
15cm's around before something pops out - quite often on the other
side of the rim. Now, I may be no expert, but I've changed a variety
of tyres over the years but never been stuck like this.



Sounds like you may be doing it wrong.

1. get the tyre over the rim so the rim is between the beads.

2. Take one side. push part over the rim and into place, then push a bit
further so that the bead sits in the middle of the rim.

3. I use both hands, tyre side I'm trying to seat upwards and the bit I
have just seated towards me. Fingers under the rim, thumbs on top.
Nowe roll the bead onto the rim using your thumbs, starting from the bit
that is already on.

4. The last part may require a tyre lever.

5. Turn the wheel over.

6. Inflate innner tube so it just holds its shape and place teh valve in the
hole. Place teh rest of the inner tube insidethe tyre and then push the
whole thing sideways so it sits over the rim, not to the side.

7. turn the wheel so the valve is next to you and seat the bit of tyre
opposite the valve.

8. turn the wheel so the valve is next to you and continue as in 3 to seat
the bead. The last bit could be tough so be careful to not pinch the tube.

9. Push the valve in to make sure it is above teh tyre bead, pull down and
inflate to squidgy.

10. Work round the tyre, pushing the sidewall in to check the inner is not
pinched. Do this both sides.

11. Inflate to working pressure and off you go..


Good luck.

...d


  #3  
Old January 18th 05, 05:59 PM
Pete Biggs
external usenet poster
 
Posts: n/a
Default

Webbo73 wrote:
after reading about good puncture-resistant tyres for commuting, I
decided to replace the maxxis default 23mm tyres on my Ridgeback
Genesis Day 0 from a couple of years ago to some Schwalbe Marathon
Pluses... I managed to find a 25mm pair of these and assumed (perhaps
wrongly) that I could go from 23mm to 25mm on the same rims with no
problems.

/snip

I would expect to be able to fit a 25mm tyre on any rim that takes a 23.
Some tyres are simply more difficult to fit, regardless of width (though
wider ones tend to be easier in general). Double-check it's a 700c.

Fit one bead so that it sits in the middle of the rim well, then force the
other on, with levers if necessary.

Assuming you mean the tyre seems too tight (I'm not quite sure what you
mean), to get round the bead-popping-off problem, push each "end" of the
bead with your thumbs simultaneously, or thumb one end and tyre lever the
other. Push hard!! If it really is a murderous job still, cut your
losses and try a different make of tyre altogether.

In case I've misunderstood and the tyre is too *loose* a fit, try fitting
with inner tube inflated more, and just keep repeating until it "takes".
Again, work on the two ends at the same time.

~PB


  #4  
Old January 18th 05, 06:40 PM
m-gineering
external usenet poster
 
Posts: n/a
Default

Webbo73 wrote:

Hi all - I'm ashamed to ask for help on this, but...

after reading about good puncture-resistant tyres for commuting, I
decided to replace the maxxis default 23mm tyres on my Ridgeback
Genesis Day 0 from a couple of years ago to some Schwalbe Marathon
Pluses... I managed to find a 25mm pair of these and assumed (perhaps
wrongly) that I could go from 23mm to 25mm on the same rims with no
problems.

I don't have the exact rim model no. to hand, but the current
equivalent model has Alex RP-15 32h and I know that mine are also
Alex, so am assuming they're the same or very similar.

The maxxis "hors categorie" tyres that came off were a soft compound
that was relatively easy to take on and off - the Schwalbes are a lot
more rigid and look almost flattened when not on the rim (i.e. the
inner diameter that should sit in the rim is splayed outwards). It
takes quite a lot of force to squeeze them into shape - so much so,
that when trying to fit them onto the rim, I can't get more than about
15cm's around before something pops out - quite often on the other
side of the rim. Now, I may be no expert, but I've changed a variety
of tyres over the years but never been stuck like this.

I didn't think a 2mm difference in tyre size would cause me a problem
- but I don't know what else to try - maybe another pair of hands
might help, but that's not much use to me if I get a puncture on the
way home one night! I even tried the tyre without the inner tube with
no joy so the only thing I haven't tried is to use the inflation of
the inner tube to try and make the tyre more into the correct shape to
fit onto the rim (as I say, at the moment, it is very splayed out). I
did partially inflate it when I first tried to put it on, but I
thought that was just to avoid getting pinch flats. Perhaps I need to
go a bit further, but then I'm not sure if I'd be able to push it over
the rim.

If anyone has any tips or experience with this rim / tyre combo, I'd
be very grateful to hear from you!!

mike



I've fitted 28's to ma2 rims, but they are not easy to fit. Problem is
the beads get sprung apart by the thick rubber underneath the thread. I
think they get easier when the tyres get older and take a set. To get
the second bead seated, you have to keep tension on the bead at all
times, to prevent it popping out. Clamp the wheel horizontal between
your body and the workbench, and starting at the bottom work your way up
symmetrically. It's a bit like fitting a tubular.
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl
  #5  
Old January 18th 05, 07:51 PM
webbo73
external usenet poster
 
Posts: n/a
Default

Thanks guys for all the suggestions - I will print out and give it a try!!

"m-gineering" wrote in message
...
Webbo73 wrote:

Hi all - I'm ashamed to ask for help on this, but...

after reading about good puncture-resistant tyres for commuting, I
decided to replace the maxxis default 23mm tyres on my Ridgeback
Genesis Day 0 from a couple of years ago to some Schwalbe Marathon
Pluses... I managed to find a 25mm pair of these and assumed (perhaps
wrongly) that I could go from 23mm to 25mm on the same rims with no
problems.

I don't have the exact rim model no. to hand, but the current
equivalent model has Alex RP-15 32h and I know that mine are also
Alex, so am assuming they're the same or very similar.

The maxxis "hors categorie" tyres that came off were a soft compound
that was relatively easy to take on and off - the Schwalbes are a lot
more rigid and look almost flattened when not on the rim (i.e. the
inner diameter that should sit in the rim is splayed outwards). It
takes quite a lot of force to squeeze them into shape - so much so,
that when trying to fit them onto the rim, I can't get more than about
15cm's around before something pops out - quite often on the other
side of the rim. Now, I may be no expert, but I've changed a variety
of tyres over the years but never been stuck like this.

I didn't think a 2mm difference in tyre size would cause me a problem
- but I don't know what else to try - maybe another pair of hands
might help, but that's not much use to me if I get a puncture on the
way home one night! I even tried the tyre without the inner tube with
no joy so the only thing I haven't tried is to use the inflation of
the inner tube to try and make the tyre more into the correct shape to
fit onto the rim (as I say, at the moment, it is very splayed out). I
did partially inflate it when I first tried to put it on, but I
thought that was just to avoid getting pinch flats. Perhaps I need to
go a bit further, but then I'm not sure if I'd be able to push it over
the rim.

If anyone has any tips or experience with this rim / tyre combo, I'd
be very grateful to hear from you!!

mike



I've fitted 28's to ma2 rims, but they are not easy to fit. Problem is
the beads get sprung apart by the thick rubber underneath the thread. I
think they get easier when the tyres get older and take a set. To get
the second bead seated, you have to keep tension on the bead at all
times, to prevent it popping out. Clamp the wheel horizontal between
your body and the workbench, and starting at the bottom work your way up
symmetrically. It's a bit like fitting a tubular.
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl



 




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