Tyre size for nemesis

Discuss light weight issues concerning road bikes & parts.
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markyboy
Posts: 653
Joined: Wed Dec 29, 2010 10:22 pm
Location: Bristol uk

by markyboy

As per title i have tried mounting 25mm veloflex tubular tyres to ambrosio nemesis rims and they just dont seem to fit properly.
Am i thinking that these rims cannot take 25mm :noidea:
I mounted them with mariposa tape and can easily pull the tyre off the rim when inflated,ive used this tape before on wide carbon rims no problems.
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by Weenie


sungod
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by sungod

there're people who run 25mm and wider on the nemesis rims, depends on how the basetape profile matches the rim bed, if you are using tape maybe you can build up the centre of the rim bed with narrow tape to give a better match?

widest i use these days is 23mm, and i prefer 22/23 front/rear, i've used with 25mm on narrower rims, never had any adhesion problem, always glue

but i've found i prefer the ride/handling with narrower tyres, and on uk roads i also suspect going narrower reduces puncture rate - seems logical if puncture rate has an element proportional to width of contact patch, though it also feels like veloflex sprinters have thicker rubber than their wider tubs

markyboy
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Location: Bristol uk

by markyboy

Thanks sun god. What I think is happening is like you said the base tape is not touching the tape if it is it's only just.
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Calnago
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by Calnago

The Nemesis rims have a rim bed radius that best matches 22-24mm tires. Being probably the most widely used rims in Paris Roubaix, even when not sponsor correct, up until about 2010, 25's were often used. Ha... that was considered fat back then. I love these rims when properly built to some nice hubs. I use them on the rain bike and run them with 25mm Continental Competitions. They work just fine, but once you reach 25mm and above, you need to be more cautious about the adherence in the center of the rim, since the larger radius tire will want to kind of sit on the edges without the middle part being able to reach the center of the rim bed. This makes for a good bond at the edges, where you want it to be strong, but if it does rip away, then there could be a weak bond in the center. I only use Mastik Glue, and have no experience with the tape. As mentioned, the "Belgian Method" (still not sure why they get all the credit) of gluing a larger radius tire to a smaller radius rim bed was to build up the center of the rim bed somewhat so that the radius better matches the tire. You can do this with layers of some kind of porous tape with a thin strip in the middle to build up the center a bit. I've never bothered. The Conti's have sat well enough and I've been able to get a good bond all across, but the Conti's also have a super thick cotton base tape compared to Veloflex. I always have to put an extra coat of glue on the Conti's tape since it absorbs so much. But I have noticed that a 25mm Veloflex was not as well bonded in the center upon removal of the tire as I would have liked. So, if I want a 25mm tire on there, I use the Conti Comps, which I think get an overly bad rap here. I love the rubber compound and I think they have the best wet weather grip of any tire I've ever used, hence they're on the rain bike. But aside from the Conti's I'm using the 24mm Veloflex Roubaix's, which aren't made anymore (they went to the 25mm width). But I think the next time I need some tires for these rims, I'm going to try the 24mm Specialized Turbo Cotton Tubulars. I've heard good things, but not tried them yet.

I have several sets of these rims... one set (maybe two) not even built up yet. But Classics season is here! Yes!! Perhaps I'll sit down one morning and build up this last fine set on the Campy Record hubs I have set aside for this. These wheels are a pleasure to ride for sure. With the non machined braking surface, they also have the best alloy braking I've ever experienced.
Last edited by Calnago on Sat Feb 24, 2018 5:06 pm, edited 1 time in total.
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Geoff
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Location: Canada

by Geoff

I agree with Calnago.

I have run the Ambrosio Nemesis for decades (and Synthesis Durex before that). Back in the day, we only ran 25s on those rims (badged as 23s, but they mic'd-out to 25s). They fit just fine. I am currently running: Dugast Paris-Roubaix seta 27s; and, two sets of Vittoria Parigi-Roubaix (nice, old, green ones!). Those sets all fit just fine.

Like Calnago, I recommend using the Vittoria Mastic 1 over either of tape or other glues. There is definitely no need to run 'Belgian' tape for tires in the 25-27 range. If you run 32's, or something for 'cross,that style of gluing may help.

11.4
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Joined: Tue May 23, 2006 4:33 am

by 11.4

These rims work fine with 25 mm Vittorias, FMBs, and other tires I've tried in that size range.

I don't know why you're having gluing problems. The tire bed is pretty wide and not so deep that a 25 won't fit fine. In fact, a 27 mm Vittoria Evo Pave III fits fine. I'm guessing the fit is ok and you may be having a problem simply with adhesion. I've had inconsistent experiences with the Mariposa tape and still do, although it's getting a bit better (possibly my own familiarity with its issues rather than the tape really changing). There's no reason why the tires shouldn't work fine. I'd start with Mastik One just because you have more points of comparison and be sure it's a good glue job. At that point you shouldn't be having any problems.

markyboy
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Joined: Wed Dec 29, 2010 10:22 pm
Location: Bristol uk

by markyboy

Thanks guys some interesting thoughts,i think i need to build up the middle of the rim a bit as i found with the eyelets thats what seems
to be the only contact point to the tyre.
COLNAGO C60 SUPER RECORD EPS
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bm0p700f
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by bm0p700f

i have 27mm vittoria Paves on my nemesis rims and they fit just fine, perfect in fact. IT all depends on the tyre as said already. I have some mavic GEL280's were a 23mm vittoria corsa sits high at the edges. again rim and tyre have to match.

If you tyre sits high in the centre you can apply lots of glue and I mean lots.

LionelB
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Location: Aix en Provence

by LionelB

27 FMB, zero issue.

by Weenie


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