19mm rims - what size tyres?

pianoleo

This month's earnings seem to be coming in higher than I'd predicted (I'm self employed) so I'm treating myself to some new tyres for my hybrid.

I'm currently running Schwalbe Marathon+ 700x35s on both wheels. Assuming I'm right in thinking that thinner, lighter tyres mean lower rolling resistance and therefore more speed for the same effort, what would my optimum tyre width be? I see from Sheldon Brown that with a 19mm rim I can get away with 28mm tyres, but his disclaimer that the chart may err on the side of caution prompted me to ask here.

So, would some GP4000s of the 25mm variety be pushing it slightly? Obviously Gatorskins are available 28mm - I'm very much open to suggestion, but don't really want to start the whole "which tyre brand and flavour is best" discussion again for the nth time this month!

Cheers

Marcus_C

Narrower tyres don't necessarily mean lower rolling resistance, the misconception has come about due to the fact most wider tyres don't tend to be inflated as much as narrower ones. If you still want some more tyres. I wouldn't go with 25c tyres on a 19 wheel, I don't know whether it's possible but there's no need for it. I'd either get some conti gator hardshells in a 28c or a good trackpump for your marathon's.

Mr Plum

The rims on my Tricross are a little wide at 17mm and I wouldn't go any narrower than a 25mm tyre. I may get away with 23s but sods law clearly states that they'll be fine for ages then pop off the rim when I'm taking a downhill corner at 40mph... Stick with 28s at a minimum - I guess Gatorskins would be the default choice.

pianoleo

Thanks Marcus_C. I've got a Blackburn Air Tower, and my marathons are kept to 6bar, their maximum (about 88psi). I notice that the narrower marathon plusses are rated to 7bar(28c) or 8bar(25c). Whilst that presumably would make for a less comfortable ride, would the decreased rotating weight not make for a quicker journey (or at least faster acceleration) ?

pianoleo

Ta, Mr Plum. I've been thinking about buying a Tricross. That or a Genesis CDF, or a Kona Jake....

Congrats on your heavy week - I was knackered after 70 miles in TWO days, so not surprised you're in pain doing that in a day!

CRAIGO5000

I've got 16mm rims on my Trek FX Hybrid and I've just swapped the heavy Bontrager select invert tyres (~500g) for some 2011 Vittoria Ziffario road tyres in 25c (~350g). You won't get a faster ride merely by reducing tyre width but you will likely increase rolling resistance by fitting a road tyre as they usually need a minimum of 100psi compared to stock hybrid tyres which are a good 20psi less.

One thing I've noticed by swapping to road tyres is that the bike handles the bumps and road imperfections exactly like the hybrid tyres did. The ride is now super smooth on slicks and not at all harsh. This is one thing I was concerned about as a lot of posts on the web were stating a tyre swap like this would make for a harsh ride. Cornering is now vastly improved, I was scared to take corners in the wet at 20mph with the 700x35c tyres, but the story is completely different now.

itboffin

You need to be aware that conti tyres come in very small, for example my hardshells 25/23 are actually 24/22 and my 4000s are more 22 than 23c. Same pretty much with the gatorskins.

pianoleo

So should I just about manage with the 28s possibly coming in at 27, do you think?

Marcus_C

pianoleo wrote:

So should I just about manage with the 28s possibly coming in at 27, do you think?

Yeah, sounds about right, i've never measured them but they are quite small for a 28. Should be fine on your wheels. If you're set on new tyres i'd go with them, they'll be a fair bit lighter than the M+'s and they're slicks, so you could notice a faster ride and better grip, not saying it'll be much mind you.

itboffin

I think with a 19c rim you could get away with 25c - which make are they?

pianoleo

They're Rigida Zac 19s - standard for my Decathlon top of the range BSO. Obviously I'd be tempted to upgrade the wheelset but assuming I'm still riding in 6 months time I'll be buying myself a new steed, with better quality components across the board.