25c Tyres - tight clearance

[monkers]

The issue I have is that the Fulcrum 5 rims have a minimum tyre size specification of 25mm

Really? I have 23mm Vittoria Rubino tyres on my carbon with 11 speed Fulcrum 5s (and did on a previous 10 speed pair of the same wheels which looked just like yours)

This may be a useful call.

Some models of Vittoria measure up bigger than the specified size. The 23mm width Corsa G+ 1.0 (TLR) for example, actually measures up as 25mm with a sidewall height of just 21mm. They may well fit those rims just fine.

If they are sufficient to meet the other considerations of grip and puncture resistance, they just might offer a good compromise?

https://www.bicyclerollingresistance.com/road-bike-reviews/vittoria-corsa-speed-2016

 

[SkipdiverJohn]

A close-clearance racing bike is fundamentally the wrong thing to be using as a winter training hack. Its a nice frame, but it's completely wrong for the intended use. Fit 23's or tubs on suitable rims and ride it for what it was made for. Use something with a sensible amount of clearance for winter riding. Almost any non-race frame from the steel era will have enough clearance. i have a late-80's 531 steel Dawes that was designed for winter riding and it will easily take 28mm Marathons, which are a tall tyre, and at a push I could even fit mudguards with 28's fitted.

 

[bigfella]

The issue I have is that the Fulcrum 5 rims have a minimum tyre size specification of 25mm

Really? I have 23mm Vittoria Rubino tyres on my carbon with 11 speed Fulcrum 5s (and did on a previous 10 speed pair of the same wheels which looked just like yours)

Yeah that is what the specs of the rims say, I suspect that I could run some 23s that come up larger.

The nub of the question is how to turn this beautiful race frame into a winter bike frame. It must remain on the same wheel type, and accept durable, grippy, and presumably puncture resistant winter tyres. Given that tyres in that category, including the ones mentioned, all tend to have a sidewall height of 24 to 25 mm, there's little scope there without compromising on the tyre characteristics that you are looking for. There are tyres at around 22mm, but they otherwise don't quite fit in with what you are seeking.

I think that you've reached the right conclusion that it can't be done without modifying the frame. My problem, and I'll own that because it's hardly your's, is that I'd hate to see that being done and not turning out well.

What you can do though is go back to the chap (Mark Reilly) who originally designed and built this frame and get his advice. In case you don't know where to find him, I've given a link below.

https://www.reillycycleworks.com/

You hit the nail on the head, and I am seeing that now, but it was always worth asking the question. I am happy to ride this bike during the winter, that does not bother me. I have another higher end bike that I am more precious about and will only ride on better weather days.

I have contacted Mark Reilly, he passed me onto someone else who has yet to reply.

Thanks.

You need to consider the limitation you place on yourself wrt the rims. Consider the extent of the jeopardy of running narrower tyres (imo a lot less than 'bending/denting' a steel seat tube). The rims have an internal rim width of 17mm. Sheldon offers the guideline of tyres best between a multiple of 1.45 and 2 times internal rim width. So minimum (Sheldon) is 24.6mm tyre width/height on a 17mm inner width rim.

Sheldon: "A general guideline is that the tire width should be between 1.45/2.0 x the inner rim width. If your tire is too narrow for the rim, there's an increased risk of tire/rim damage from road hazards."

With that in mind, then consider fitting a tyre that (we 'know') comes in over spec (4000) in 23 flavour to give that extra mm of clearance.
This site bicyclerollingresistance.com gives measured/spec comparisons in a table. Their measurements of 25-622 tyres are " All size measurements are taken at an air pressure of 100 psi / 6.9 bars on a 17.8 mm inner width rim."
HTH
Plenty of 4000 23s on the bay - are selling at a discount (4000s have been discontinued).
Or maybe some 24mm Vittorias?
https://www.ebay.co.uk/i/133619394339?

Thanks for that, I had been looking at 24mm tyres as that might be a good compromise - but they are few and far between! I would rather not run the rims out of spec really, and possibly risk the tyre coming off the bead or something. The wheel choice does not appear to be the best fit for the frame.

Someone on the Wiggle site asked if 23mm tyres could be fitted and the Wiggle operative replied that they could. How much store can be placed on that I don’t know.

That is interesting to know, I think people do run them on these rims; but I would rather not run the risk on a 35mph decent!

Well wiggleman (trying to sell wheels/tyres) is correct: they physically 'can' be fitted. But the Fulcrum site says from 25mm to 50mm - of course the latter dimension is 'barking' - far too wide and prone to rolling around and associated instability in corners/ on bends.

Yeah I agree, I suspect they will fit, but how safe they will be I do not know!

This may be a useful call.

Some models of Vittoria measure up bigger than the specified size. The 23mm width Corsa G+ 1.0 (TLR) for example, actually measures up as 25mm with a sidewall height of just 21mm. They may well fit those rims just fine.

If they are sufficient to meet the other considerations of grip and puncture resistance, they just might offer a good compromise?

https://www.bicyclerollingresistance.com/road-bike-reviews/vittoria-corsa-speed-2016

Thank you, I have been looking into them. In the meantime I picked up a pair of Vredestein Fortezza Senso All Weather tyres in 25c and put them on last night. They do clear better, at 95psi the moulding in the centre of the tyre, which wears off after a couple of rides, does just touch the frame in one place. I might just ride it at that and accept a bit of paint wear until the tyre wears slightly.

A close-clearance racing bike is fundamentally the wrong thing to be using as a winter training hack. Its a nice frame, but it's completely wrong for the intended use. Fit 23's or tubs on suitable rims and ride it for what it was made for. Use something with a sensible amount of clearance for winter riding. Almost any non-race frame from the steel era will have enough clearance. i have a late-80's 531 steel Dawes that was designed for winter riding and it will easily take 28mm Marathons, which are a tall tyre, and at a push I could even fit mudguards with 28's fitted.

I know I know, to some it might seem a waste. But I have a far more valuable bike with a top end groupset, so riding this in the winter does not bother me really. The question on modifying the frame really was about making just 2-3mm of clearance approximately, that is all it needs.

 

[raleighnut]

Gawd that's tight, even tighter than my TT frame on 25's

 

[bigfella]

I think part of the problem is that my frame has vertical dropouts. As you have horizontal, you can get the wheel/tyre in with no air in it and inflate it after, giving you that clearance.

 

[raleighnut]

I think part of the problem is that my frame has vertical dropouts. As you have horizontal, you can get the wheel/tyre in with no air in it and inflate it after, giving you that clearance.

Yep but it's a pain having to let the tyre down to get the wheel out.

 

[davidphilips]

Carlsbrough option would be to fit 650b wheels and then play about with the brakes can be done with little cost apart from buying the smaller tyres and wheels but this can be of set to a degree by selling your wheels and tyres?.

 

[fossyant]

My Ribble 653 is incredibly tight with 23mm. I could only just fit raceblade longs and it was very tight, too tight really with the support brackets at the brake bridge. I've ordered some 25c tyres and won't be re-fitting the guards. Even without guards there is toe overlap with the front wheel.

 

[raleighnut]

My Ribble 653 is incredibly tight with 23mm. I could only just fit raceblade longs and it was very tight, too tight really with the support brackets at the brake bridge. I've ordered some 25c tyres and won't be re-fitting the guards. Even without guards there is toe overlap with the front wheel.

Funnily enough the TT bike I posted a pic of is 653 too, I wonder if something in the tubeset made it condusive to short wheelbase bikes.

 

[fossyant]

Funnily enough the TT bike I posted a pic of is 653 too, I wonder if something in the tubeset made it condusive to short wheelbase bikes.

I think it's down to being a TT bike, and mine was a race frame. The 'builder' who made my Columbus SLX actually did a slightly longer wheel base and 'slightly' more clearance. It's more stable at high speed (50 mph plus) than the Ribble.

 

[MichaelW2]

Funnily enough the TT bike I posted a pic of is 653 too, I wonder if something in the tubeset made it condusive to short wheelbase bikes.

The high end chainstays were cut short to maximise rear triangle stiffness. Using over sized tubes was not an option and heavier tubes were....heavier.
Audax and touring bikes were sometimes made in these tubesets with longer chainstays.
Around this date , some frames came with curved main seat tubes for even tighter tear triangles.

 

[Ridgeway]

If you change to wider rims those tyres will sit lower, just did some testing here (different tyre/rim combo) but in my case it was about 4mm less in OD

 

[Ajax Bay]

the Fulcrum 5 rims have a minimum tyre size specification of 25mm. I would rather not have to change wheels as well...

OP doesn't want to junk the wheels. @Ridgeway 's suggestion a change to wider rims is dodging the issue (though might succeed).
The solution to this has to be to fit tyres (23s say) which come up a bit wide/high (eg 4000s). The jeopardy of running 24mm tyres on this rim, even descending at 35mph (in winter, rider choice) is small, and the risk can be mitigated by running at decent pressure, checking that before each ride and avoiding attacking down hills. Far greater risk of slipping out on ice or gravel, imo.

 

[bigfella]

Carlsbrough option would be to fit 650b wheels and then play about with the brakes can be done with little cost apart from buying the smaller tyres and wheels but this can be of set to a degree by selling your wheels and tyres?.

Yeah I did think of this, I think it would require longer reach brake calipers too. Not sure of the pros and cons of 650s...

My Ribble 653 is incredibly tight with 23mm. I could only just fit raceblade longs and it was very tight, too tight really with the support brackets at the brake bridge. I've ordered some 25c tyres and won't be re-fitting the guards. Even without guards there is toe overlap with the front wheel.

That is interesting, there is no issue with toe overlap on my frame, it is just the incredibly tight rear end.

The high end chainstays were cut short to maximise rear triangle stiffness. Using over sized tubes was not an option and heavier tubes were....heavier.
Audax and touring bikes were sometimes made in these tubesets with longer chainstays.
Around this date , some frames came with curved main seat tubes for even tighter tear triangles.

Interesting info, thanks. My particular frame is constructed with Dedacciaio Zero HT tubing, I am not aware what the equivalent Reynolds tubing would be.

If you change to wider rims those tyres will sit lower, just did some testing here (different tyre/rim combo) but in my case it was about 4mm less in OD

I read about this; there is a theory that a tyre forms a balloon shaped cross section so using a wider rim in some cases could increase the tyre height.

OP doesn't want to junk the wheels. @Ridgeway 's suggestion a change to wider rims is dodging the issue (though might succeed).
The solution to this has to be to fit tyres (23s say) which come up a bit wide/high (eg 4000s). The jeopardy of running 24mm tyres on this rim, even descending at 35mph (in winter, rider choice) is small, and the risk can be mitigated by running at decent pressure, checking that before each ride and avoiding attacking down hills. Far greater risk of slipping out on ice or gravel, imo.

Over the past couple of days I have tried some Vredestein Fortezza Senso All Weather tyres in 25c, I measured them inflated to 95-100psi with vernier calipers and they were 25.5mm-26.2mm installed. So they are coming up slighly large, even though I read online that they come up small.

Thank you though, I have come to a conclusion to run the rims *very* slightly out of spec as you say... I have taken the decision to indeed switch to 23c tyres knowing that they actually come up slightly larger. I have ordered some Continental GatorSkin wire bead tyres in 23c which I am aware come up slightly larger as per the GP 4000s. They should be here later today, looking forward to getting them on and seeing the clearance, I will post a photo later this afternoon.

If I was using this bike during the summer/better weather I would have probably opted for a pair of Veloflex tyres, the same as what were installed when I obtained the bike. Turns out the original owner must have gone through all of this himself!

 

[Grant Fondo]

I'll second those comments on the frame, very nice. I would stick with 23c myself although it does help having a bendy seat tube occasionally