After having tried 25mm tires labelled size ( GP5000TL , GP5000, GP4000S2, Turbo Cotton, Schwalbe Pro One )
28 mm tires labelled size ( GP500 TL )
On clincher disc rims (not into rim carbon clincher, often heavier than the disc ones due to the braking surface)
at least for generic asian rim LB, or Venn, may be different for Schmolke, Bikebeat, Tune.
: - VENN 35 TCD ( 19mm internal 26 26,5mm external width ) updated version is wider but haven't tried them , 400 410 gr measured
: - VENN 507 TCD ( 21mm internal, 28mm external width ) manual lay up, 495gr measured
and finally
: - Light Bicycle 56mm ( 23mm internal, 30 30,5 external width) : 460 gr each measured
My review on rims and 25 vs 28mm tires: not considering tubulars here , other topics thanks
I think both sizes will coexist for a long long time. I am 1 meter 87cm and 65 to 70kg , more of a climber rouleur, spinner , not that powerfull 290 FTP
I don't have any power meter anymore, but strava, repetitions, cardio etc. They are situations in wich 25mm tires with the VENN rims were better. It was the racier conditions on good to average roads. Including climbing. They measured up to 28 29 mm on theses rims. The 35mm behaved like low profile alus rims box but even calmer. The 507 were very neutral in the winds, they felt like lower rims most of the time maybe except super longs climbs and double digit super hards % short climbs. I tested 25 and 28mm tires on them. The 28mm tires were a bad change in terms of lateral wind catching on the venn rims. Especially on the 507. You definetely could tell these were aero optimized for 25mm tires.
Then 28mm tires on Light Bicycle 56mm rims. The GP5000 TL measured up to 30mm . Pressure max according to conti should be 6,5 . I didn't put them as high. 6 was the highest on good roads and I think it defeat the purpose of wider rims and tires no ? But then again why would you need 30mm tires for road racing, gran fondo, climbing on goods to average roads ? Between 4 and 5,5 depending on the roads, strade bianche, fire roads is the right kind of pressure I think. 28mm tires are more for heavier people or for riding on specifics conditions if racing ( strade bianche, ronde van vlanderen, nova eroica). Ultra endurance long distance cycling ( transcontinental race, trans am bike race) or commuting are where these wheels and tires shine for me... They allow to have more comfort, nearly same average rolling resistance except uphill on good roads, taking more bumps and small potholes if you want it. The grip on the flat and downhill is insane, really. The newer rims 56, 38 mm and 50 mm from light bicycle are optimized for 28mm , the wind on the side makes them a little bit slower than venn 507 but they are better than venn 507 with 28mm tires. They don't have wind turbulences issues between the rim bed and the tire. They are perfect if you think about the 105% rule.
The disadvantages for me for a racier bike set up for criterium, gran fondo , climbing :
- more frontal surface , noticeable above 40 45km/h
- less reactive
- heavier
- tires bouncing around at adapted pressures and feeling " dead "
- I don't like how they behave while climbing and out of the saddle , can't push them, sorry
- Harder to mount on than 25mm tires on narrower rims, but manage to do it by hand horizontally without tire lever
So I think for my disc road bike, I'll have:
- one pair between optimized for 25mm tubeless or latex inner tubes clincher ( 35,38,40,45 max 50mm )
- one other pair optimized for 28mm tubeless tires for long distance brevet, training on bads roads, fast commuting
and maybe a tubular pair ...
I think the rim width range for 25mm tires should be like 17mm to 21mm internal AND 27 28 29 30mm external width.
In that range you have OEM chinese rim ( LB, Farsports, VENN).
Expensiver, a bit lighter and more reactive with the same components spokes hubs according to some friends you have : Bikebeat nice price made in Germany, Schmolke etc.
And then " system wheels " : Campa Bora WTO, Fulcrum 4D, Shimano C40 even if heavier, lower and narrower. With system wheels, you know what you"re buying and often they have very good geometry ( 2:1 rear spokes build, even better for C40, less differential tension between DS and NDS ).
I really like Campa and Fulcrum carbon wheels overall; I wish they were a bit wider but they are the best overall to me. Compared to Roval CLX50 ( average buld, bearings ..)
What are your opinions ?
Thanks
