I realise gearing has been covered many times, and trust me, I've read all the posts! I have recently switched From SS to 1x10 with 36 upfront and find this fine in the peaks etc. however, it is a fairly light weight Xcode hard tail. I am currently building a hardcore hardtail, in 650B with heavier rubber etc and have been offered a 32t chainring. My concern is I will spin out in 32x11 too often? On the road, fine I don't care, but what about getting enough speed to clear a big double or similar?
It also depends on peddling style, I am aware, however, as I have recently switched I am still mashing (comfortably) a fair bit, so as I use gears more I will probably adopt a more spinning style. The concern r.e. Top speed is still there however.. Thanks in advance 🙂
Depending on the biggest sprocket on your cassette and where you ride obviously, but personally I wouldn't go lower than a 36t or maybe 34t on the front. But then I'm a masher 😉
I'm on 30t at the front because I'm a lard-arsed old git.
for a burst of speed to clear a double I'm assuming you could be revving at 120rpm quite easily, probably much faster than that.
120 rpm x 32/11 x pi x 0.7 (conservative on wheel dia with big rubber on) would give you 767m/min = nearly 30 mph.
How big is this double?
While waiting for the coffee pot, i just calculated
Assuming 120rpm approach speed, and a 45deg take off angle, and a landing ramp at exactly the same height as the take off one (ie. on a flat piece of ground). And no losses due to suspension / air resistance, etc.
The time of flight would be about 1.8s, and your horizontal vector would be about 9m/s, so you'd be able to clear a double about 16m across.
Coffee's brewed now.....
If you're a riding a trail where you have to PEDAL fast enough to clear a big double, you're either at redbull rampage, or riding a rubbish trail 😀
30 on front here as well.......im a weekend warrior. So what? 8)
jonv is better at maths than me so I took my 32/11 bike up to the woods and spun like crazy then checked the GPS.
29.5mph.
I'd be hitting the brakes for a big double at that speed - and would prefer to spin rather than mash on the approach.
I'm pretty fit (or at least was) and run a 32 and have done for the last 4 years. It suits me perfectly- I ride reasonably quick but spin and like riding big mountains. I ride mostly in the peak and never really suffer on the downs, I've got some good KOMs. I have run this set up on everything from my old giant anthem xc race bike to my big 160mm bikes.
32t (1x10) here on a 29er around Yorkshire, Peaks. Find can get very spinny on the fast road sections but other than that seems fine.
32t and 11-36 cassette on my 160mm bouncy bike and 34t and 11-36 on the hardtail, job done, allows me to shred the gnar, roost the brown pow, clear big jumpz, high five my bro's and then climb back to the top for some more...... 😆
No idea why folk think a 32t ring is too small... see the above calcs for what speed you're spinning out at! I don't think I've ever truly spun out on 32-11, but then my riding doesn't consist of fire roads. If I did spin out on a fireroad I'd happily freewheel for a few seconds until the long fireroad hill flattens out!
I guess when pedalling at obstacles I'm usually somewhere on the middle of the cassette with the 32T ring.
In short, 32T is FINE!
From http://www.machars.net/bikecalc.htm , at 95rpm in 32-11 you're doing 25mph. That's enough to clear any jump I know (maybe not the ft bill tables, but you could up the rpm on approach to those!)
As above: 32 is fine. I'm using all of the sprockets on an 11-36 cassette on a regular basis, but that's what they're there for. Climbing in the Peak, Lakes and Northumberland (up for 40k days out) has been fine.
I do spin out occasionally however. It's not a problem at all in day-to-day riding (my other bike's a singlespeed, so it happens all the time), but I'll put a 34-tooth ring back on the front for racing (enduro stuff).
34T 11-36 on 26er HT here and love it. Didn't like 36T last year on FS, but I was in poor shape after months off bike so not that surprising.
I bet someone's worked out a rule of thumb for how many teeth difference there are on drive rings between the given wheel sizes... here's some sums though.
((32/11)x26) = 75.6 gear inches and ((32/11)x27.5) = 80 gear inches.
((36/11)x26) = 85 gear inches and ((34/11)x26) = 80 gear inches.
So, 32t and 11t smallest on your new 650b looks like it should produce about the same speed for effort as a 34t vs 11t on a 26er.
Been riding with 32 x 11-32 on my old SC Bullit for ages. Works great both on trails and for freeride. Spins out at +22 mph / +35 km/h.
/Leo