[PissedOffCil]

Hello folks,
Yesterday I had my first "important" race of the season. I'm very happy with my result, a first finish in the top tier! Yet, I've noticed something during the race, that is I don't roll as fast as other riders on dirt roads on the downhills. Given I'm either in 44x11 or coasting and getting passed, I concluded that my tire RR is probably the culprit.

I'm currently running a Geax Barro Mountain TNT 2.1 rear and a foldable FireXCPro 2.1 front. Both are setup tubeless (rear on 819, front on Stan's converted 717) I really love the Geax on the rear, probably the best all-around tire I've ever ridden so I don't plan on changing it. I suspect the front is slowing me down a fair bit and since it's fairly worn out, I'm looking for a replacement.

Up to now, I feel the Serac XC would be a good contender. I want a rather all-around tire since I'm not the type to change tires for race day and this looks like it's rather fast rolling. Maybe I should look for a tire with low center knobs and taller side knobs, I'm not too sure. The Serac though would have to be the UST version to be used on the 717. In fact I prefer going with a "tubeless ready" tire if possible.

So, will the Serac XC help lower my RR while still providing godo all-around traction? Any other suggestions? Am I blind to my weaknesses and the tire has nothing to do with my slower speed on DHs?

Thanks

 

[ferday]

as you go faster, air resistance starts to become significantly greater than rolling resistance, and by the time you've hit 30-40km/h (easily enough on fireroad descents) the air resistance is far more than double the RR.

the fireXC is NOT a fast tire, but i doubt you'll gain much that much top end speed with a tire change...look for something else to be the culprit.

 

[PissedOffCil]

look for something else to be the culprit.

Suggestions?

One way or another, I'm looking for a FireXC replacement with the aformentionned criterias... So?

 

[ferday]

Suggestions?

One way or another, I'm looking for a FireXC replacement with the aformentionned criterias... So?

as far as technique...i can't help. i race SS only, so i'm always being passed on the flats and really fast DH sections

for tires, i prefer as much grip as i can get up front. to that end, i like the panaracer rampage in the front for varied conditions, also the maxxis ardent seems pretty fast so far this season. if you have high traction on the course, the maxxis crossmark is wicked fast with surprising grip on hardpack.

 

[gvs_nz]

If you like the Barro mountain why not a 2.3 folding on the front. It's not a big 2.3 and in that size has the sticky soft compound good for wet tree roots. Not as aggressive looking as Fire xc pro but extra width should make up for it. Enough for xc races anyway.
I've still got one and like it. Fast, good all rounder and good cushy ride.
Plenty of other more expensive options though depends on your budget and how much grip you want. Schwalbe nobby nic.and rocket ron 2.25 would have more grip and faster than Fire Xc. The extra volume of 2.3 or 2.25 tires will give you more speed over tree roots and rocks.

 

[scottzg]

as you go faster, air resistance starts to become significantly greater than rolling resistance, and by the time you've hit 30-40km/h (easily enough on fireroad descents) the air resistance is far more than double the RR.

Came here to say the same.

I'm 230lbs, and i can EASILY pass anyone on a long straight descent, and i run big knobby tires. Inertia is king. Check your hub bearings, body positioning, look for banks to push against in the corners, and carry as much speed into the descent as possible. RR is such a small piece of the pie.

 

[shiggy]

as far as technique...i can't help. i race SS only, so i'm always being passed on the flats and really fast DH sections

for tires, i prefer as much grip as i can get up front. to that end, i like the panaracer rampage in the front for varied conditions, also the maxxis ardent seems pretty fast so far this season. if you have high traction on the course, the maxxis crossmark is wicked fast with surprising grip on hardpack.

I use to pass gearies (and fullies) on the downhills racing my singlespeed, even with grippy "slow" tires. Aerodynamics are key. Simply keeping your elbows tucked in and dropping your chin to stem level can let you fly, especially if you hold it through the curves, which is where the grippy tires come into play.

 

[gvs_nz]

Aerodynamics is probably a key factor on smooth down hills where you can just crank it in 44 x 11.

Wish I raced XC courses where downhills are smooth enough to worry about aerodynamics.I'm usually hanging on for dear life, arms pumping and trying to pick the smoothest line I can.

 

[PissedOffCil]

They're not XC races btw, but endurance races. The lower RR also sums up to much saved energy, I was looking forward to that too! I also do XC races but only for training, they are rougher which is why I'm looking for a all-around tire, not pure hardpack.

I must admit though that I never really thought of aerodynamics even if it now sounds obvious, I just thought of that for the roadie... I'll give it a try for sure.

As far as the tire is concerned, I was thinking last night of going for the Barro Mountain on the "Speed" direction. I wouldn't go for a tire over 2.1, I find they fold on the 717 rim in corners, or it would have to be a very small 2.3.

What about a tire with smaller center knobs and big side knobs for cornering? Anybody have good experience with these kind of tires? Something like the Aspen maybe... The 2.1 120TPI is very lgiht, even the 2.25 120TPI has reasonable weight and given Maxxis tires are on the small size, it would be fine on the 717 I think.

BTW, nobody has an opinion on the Serac???

 

[jeffscott]

Try a Conti Vertical tread type...round, high volume Maxxis Ignitor. 2.3 inch or more.

Ensure pliable casing (not like Nevegal).

Try a 46 or a 48 tooth front ring.

Get aero.....

Remember it don't matter how fast you enter the corner it only matters how fast you leave the corner...

Practice drifting on gravel and washboard.

Serac sucks on gravel.

 

[shiggy]

They're not XC races btw, but endurance races. The lower RR also sums up to much saved energy, I was looking forward to that too! I also do XC races but only for training, they are rougher which is why I'm looking for a all-around tire, not pure hardpack.

I must admit though that I never really thought of aerodynamics even if it now sounds obvious, I just thought of that for the roadie... I'll give it a try for sure.

As far as the tire is concerned, I was thinking last night of going for the Barro Mountain on the "Speed" direction. I wouldn't go for a tire over 2.1, I find they fold on the 717 rim in corners, or it would have to be a very small 2.3.

What about a tire with smaller center knobs and big side knobs for cornering? Anybody have good experience with these kind of tires? Something like the Aspen maybe... The 2.1 120TPI is very lgiht, even the 2.25 120TPI has reasonable weight and given Maxxis tires are on the small size, it would be fine on the 717 I think.

BTW, nobody has an opinion on the Serac???

Fastest tire I have used lately, climbing/descending/cornering, is the Panaracer CG XC.

 

[twenty6black]

I like the thread.....there are times that I find myself 'on top' of other rider and wonder about there RR.

Here are some things I check ALL THE TIME:

1) wheel spin - hold the bike up and just spin the front and the back. How long do they keep spinning for? Do they stop abruptly or do they slowing - eventually stop ?

2) spin the crank backwards...does it wnat to spin backwards, is it free spinnning. BB and RD pullies need TLC.

If you have the above all set and good - then start thinking about tire pressures and SPANDEX! hahaha

enjoy....LC

 

[shiggy]

I like the thread.....there are times that I find myself 'on top' of other rider and wonder about there RR.

Here are some things I check ALL THE TIME:

1) wheel spin - hold the bike up and just spin the front and the back. How long do they keep spinning for? Do they stop abruptly or do they slowing - eventually stop ?

2) spin the crank backwards...does it wnat to spin backwards, is it free spinnning. BB and RD pullies need TLC.

If you have the above all set and good - then start thinking about tire pressures and SPANDEX! hahaha

enjoy....LC

2) If you are coasting down a hill the BB and RD pulleys are not moving and not a factor.

 

[PissedOffCil]

Fastest tire I have used lately, climbing/descending/cornering, is the Panaracer CG XC.

The CG XC seems like a decent alternative. How's the grip in wetter conditions? Are you using it front or rear?

My wheels spin very easily, not a problem.

 

[shiggy]

The CG XC seems like a decent alternative. How's the grip in wetter conditions? Are you using it front or rear?

My wheels spin very easily, not a problem.

Does fine in the wet, but it is not a full mudder. It does like lower pressures for grip/control which I have measured as faster on a varied loop.

Run them front and rear.

 

[Le Duke]

2) If you are coasting down a hill the BB and RD pulleys are not moving and not a factor.

Not to mention how the wheels spin when unloaded have very little in common with how they'll act when under load.

 

[PissedOffCil]

Not to mention how the wheels spin when unloaded have very little in common with how they'll act when under load.

Yes indeed. One can end up wasting a fair amount of time removing brake pad rub when it has little to no impact once a 160lbs rider is on the bike.

 

[gvs_nz]

I had no problem running 2.3 Barro mountain on 17mm rims[Alex TD17]. They aren't a big volume tire. Similar size to a Ardent 2.25 and a Captain 2.2.[ 55mm tread/52mm casing at 40 psi]
Squirms on the rear at low pressure though but gives the same comfy ride at higher pressure [28 psi +] than other tires run at lower pressure[22 to 25psi].
I ran it at 25 psi on the front no problems.

For endurance racing I run the biggest cushiest tire I can on the front [Ra Ra 2.4] for better momentum over rough objects, less fatigue and more cornering grip.Unnecessary braking is also wasted energy.

 

[PissedOffCil]

Yeah I'm leaning towards the Barro Mtn. I really love it in the back (huh?) so I bet it'll be a pleasure up front (WTF?)

Hehehe

 

[jeffscott]

Yes indeed. One can end up wasting a fair amount of time removing brake pad rub when it has little to no impact once a 160lbs rider is on the bike.

Really I hate drag and it only takes a couple of seconds to eliminate the any rub.