hobkirk

How much wheel axle play is OK? How much tire wear is OK?
(I know both Q's are lame, but I really am curious.)

My bike rear tire seems to slide sometimes on hard right turns taken at speed (T intersection, 20-25 mph, downhill aided!). It's happened several times. It sort of feels like the tire is rolling off the wheel, and the first time I checked to make sure the tire felt fully pumped.

The rear tire is a Specialized Roubaix 25/28 (a new size). I put it on last year and am surprised to see it has 3,300 miles. (I was surprised it had so many miles when I checked my log.) I can feel that the tread is thinner, but I've often gone until I see the first signs of the underlaying cord before I replace.

I measured the play in my rear wheel (the front has significantly less) -

• 1/8" toward drive side at rim, 1/16" opposite
• I'm pushing it firmly and measuring distance from brake caliper

I replaced both wheels 4 years ago (about 10 K miles). I am not gentle on wheels: I weigh 230, I sometimes fail to avoid holes in the pavement. They seem to have worked well. But they've developed play.

• My original back rim had fractured at spoke holes (twice - the first time I replaced it with a new rim and laced it myself, bought a new rim through a web bike store)
• The next time, Belmont Wheelworks said it was not rebuildable - the wheels came on my 2007 Specialized Roubaix Elite Triple, $2,500 list
• I replaced my wheelset with takeoffs from a Specialized SL4 Expert Roubaix (list price was $5 K so I figured they would be a step up)
• An experienced tech (foreman) at my LBS adjusted the cones a year ago, but he said it might need more work, and it might not be fixable. (I didn't really understand why he wasn't more definitive, but I figured he feared he;d need to rip into the hub and that might get expensive.)

I included some pictures and some specs on the wheels.
THANKS

Specs (found in some random post, I have not verified) -
· Rear Hub: DT Swiss Axis 32 hole, 3- cross lacing on drive side, Radial on non-drive side
· Front Hub: DT Swiss Axis 24 hole, Radial lacing
· Hub Color: Black
· Compatibility: Shimano/Sram 8, 9, 10
· Rims: Etrto 4.0, machined sidewalls, 700c, 14mm width, 28 mm height, Clincher, Presta Valve
· Rim Color: Black with machined side walls
· Spokes: DT Swiss double Butted
· Spoke Color: Black
· Hub Spacing: 100 mm front, 130 mm rear
· Weight: 1,700g

Pic's of the tire and the hub

https://photos.google.com/photo/AF1Q...vknz86hlC9vAvk


https://photos.google.com/photo/AF1Q...8tHWriYipuDblo

fietsbob

slow down (or go down) in those corners..

10 Wheels

I Like Slow Down.

55murray

Um, that there is bit on the crazy...

Your rear tire probably needs to slide to do that maneuver! Anyway, better the rear than the front...

trailangel

IMO there should be no play whatsoever in wheel bearing after being firming mounted on frame with quick release.

cyccommute 

Yup.

Nope. 20 to 25 mph on a hard corner isn't that fast but fast enough that you don't what the tire sliding in the corner. I think the sliding is linked to two issues. First is the play in the wheel. There should be none...zero, zip, nada. A wheel should roll freely but with zero play in the bearings. If the wheel wobbles under load, it could result in the tire breaking free.

The other issue may be technique related. Cornering hard at speed should be done with the inside pedal up and the rider pushing down on the outside pedal with all their weight. The rider should also be pushing down on the outside handlebar as well. This presses the tire into the pavement and pulls the rider through the turn.

Additionally, while the rider needs to lean into the corner, there is a limit to how far over we can go. Our center of gravity is high and if we lean over too far, the wheels slip out...which is usually bad.

Eggman84

I would think that if the bearings/axle were loose, that you should have the same movement to both the right and left. I think what you are measuring is just the rim flex (for want of a better term) under a side load; rims are only so stiff. I think what you are feeling in the turn is the tire slightly rolling over on the rim. Generally this happens when the tire is "under inflated" but can also happen when a too big a tire is mounted on a narrow rim (which doesn't sound to be the problem in your case). I would guess that the tire is occasionally "under inflated" (unless you religiously check it before each ride). I know my tires can feel well inflated (maybe a little low but not enough to take the 2 minutes to top off) but then once riding them I can tell they are lower than I thought.

Bike Gremlin

As for cornering technique, I wrote here about it in detail:
Fast cornering on a bicycle - on paved roads - Cycle Gremlin

AnkleWork

Why not just fix the play and test ride?


Why not verify with your actual observations? What's your post really about?

maddog34

axle play, or not... you are exceeding the tire's traction limits, period...

now... the wheel will flex when cornering... add the axle slop, and your rear wheel may be dragging on the brake on one side, which will increase traction loss!

and the Mechanic is not a good one.... a loose axle is a mistake, plain and simple! Are the cones rough? are the balls worn/rough? He SHOULD have recommended a fix, not dodged the work with excuses, then given you the choice to do the work..

as to that tire... if it's lasting a long time, the RUBBER COMPOUND is a hard type, and THAT will cause loss of traction, eh? do you want to have a long lasting tire, or limit drifting through corners?

tire surface tread depth is nearly irrelevant to TRACTION on dry pavement, btw...

want to get through corners a bit quicker? try hanging off the inside of the bike, and getting your butt off the seat some... the "hanging off" thing shifts your weight to the inside, and keeps the tire more vertical to the ground... getting your butt off the seat shifts your weight to a lower point on the bike some, and DECOUPLES your weight from the bike, allowing the bike to follow the surface more quickly! your weight is carried by the BB, and that PIVOTS... both tires move more freely in response to the surface variations! cool, huh? think of it as "suspension" for your ridged framed bike! Your legs and the crank spindle become suspension.....

and slow down a bit.... unless you enjoy road rash.... nothing is quite like peeling a scab off of the sheets in the morning... and then, there's that second day crunchies thing... and pants rubbing on the wound(s)..... and tiny bits of gravel that become part of your skin.... and the occasional busted collar bone.... and dislocated shoulders.... those are always interesting...

Bike Gremlin

This is counter productive for road cycling. Works good on a motorcycle, but for a bicycle not so much, for several reasons.

andr0id

The wings on my 787 keep flexing when I fly it.
Is that OK or should I get the manufacturer to replace it?





yeah, hi-tech, lightweight materials flex. That includes your spokes and rims.

79pmooney

As many others have said above, get rid of the play. Also, is there a chance that you do not have enough weigh on the rear wheel when you turn? I have had this problem with many bikes because I tend to pull myself forward both when I am going hard and when the going gets iffy. Bikes with long front ends and short chainstays help me a lot on corners. More common bikes with moderate front ends and longer chainstays are very sketchy for me if I do not remember to straighten my arms and push myself back to weigh the rear wheel.

Slippery tread, stiff casings and too high a pressure all make this worse. 3000 miles is a lot for any tire. Highly dished wheels have rims that are poorly supported by the right-side spokes unless special measures have been taken. (Very high right side hub flange, asymmetrical spoke holes on the rim ... You mentioned right hand turns.)

Ben

79pmooney

Re-reading your post, re: getting rid of the play. This may be the result of pitted cones or (less likely) cups. This leaves the mechanic with several choices: leave a little play, set the hub up so the bearings feel quite rough or replace the cones (and maybe the cups). The latter, replacing the cones is the only "right" solution but those cones may not be available. If these are cartridge bearings, the issues are a little different but they too wear out and replacements not always available. (I would guess that Belmont Wheelworks would be a better avenue than your LBS here.) If the play cannot be removed, it is new hub time which usually means new wheel time. It does sound like you may be hard on wheels and might do well to do some research before you spend the money in order to get a wheel that will serve you better.

Ben

davidad

I couldn't see the pictures and DT doesn't show an Axis hub. Dt doesn't make a cup and cone wheel and to my knowledge never did.
Any wheel will flex when you push against it. A bike wheel is designed primarily for radial loads and doesn't handle side loading well.

maddog34

ok... why?

Bike Gremlin

Bicycle wheels are pretty bad at taking lateral loads. Leaning body, with a bike straighter puts more lateral stress (and bend) on the wheels and rims. On motorcycles this isn't a problem.

Hanging off doesn't allow nearly as much weighing on the bicycle towards the ground by the rider. Motorcycles are very heavy, and the engine/weight distribution allows for a lot of front wheel load - on a bike it's not the case. Hanging off leaves very little weight on the front wheel - so much that it reduces traction. I've tried the technique and the front wheel slides at cornering speeds where the leaning in line with the bike makes leaves wheels still with traction.

On a motorcycle, hanging off allows for sharper turning, since the max lean angle is limited by pegs dragging on the ground, while hanging off allows for sharper turning with the same lean angle. On a bicycle, maximal lean angle is not limited by that - tyres will slip long before pedals (if the outer pedal is placed at 6 o'clock) start dragging on the ground.

Wrote about it here, with pictures:
Fast cornering on a bicycle - on paved roads - Cycle Gremlin

maddog34

the pic in your blog piece shows the rider's upper body leaning to the inside of the corner... more than the bike is leaned.

turning in abruptly will possibly send the front wheel into a slide, and will have the bike needing to become more vertical in the corner, possibly sending bike and rider off the outside of the corner, or even "high siding"... OUCH!

what happens when a rider hangs off the low side of a bicycle? the tire is more vertical to the ground, reducing the tendency of the tire to "ROLL AROUND" under high side load.... which is what the OP mentioned feeling before his back tire slides out...

when i mentioned hanging off the inside, i wasn't talking doing any knee dragging, just a bit to keep the bike more vertical... watch some super fast riders some time, ok? they lean their bodies to the inside of the corner... remaining vertical to the centerline of the tires will make the bike harder to steer, and DEATH GRIP may set in... not "dead grip"... DEATH GRIP. And setting your body slightly to the inside of a turn should not shift weight off the front tire, unless your butt has moved backwards... which would weight the rear tire more... possibly causing loss of traction to.... the REAR wheel (EXACTLY what the OP mentions)... unless you've turned into the corner too abruptly... which YOU RECOMMEND, btw... which causes the bike and rider to... do what? oh, yes... Either lose front wheel traction, OR, STRAIGHTEN UP, and head off the outside of the corner, causing panic, which you say causes other issues.... hmmmmmmmmm.... not good!

and BALANCE has only one L, Gremlin...

To the OP: For best results... do all braking before initiating the turn... gradually release braking, then turn in GRADUALLY to avoid sudden load shifts on the tires... sudden motions, of any kind, will possibly cause traction loss. Ride loose above the bike... this also reduces sudden load changes, and allows the tires to better maintain traction.... even one fast twitch when traction is at it's limits, and you may crash.... RIDE LOOSE AND SMOOTH.... add a bit more weight to the outside pedal... watch what happens... the bike leans less off of vertical, and your body shifts slightly to the inside... one might say you're now "hanging off the inside"...... heck, just hang your leg out there, watch what happens! the bike TURNS that way... imagine that! huh.......

here's a fun thing... push on the right side of the handlebars a bit while riding straight up, directly forward... what does the bike do? it turns to THE RIGHT!!!!.. turning a bike is all about WEIGHT SHIFTING... determine WHY the bike turns the opposite way... CLUE; it's built into the geometry of the frame/fork... and that geometry is why two bikes, built with exactly the same tubing, etc., but just a minor alteration of the geometry, will ride differently... some will spook you into riding slower, others inspire confidence, and are "faster".

oh... and Gremlin, buddy... ride a modern road racing M/C sometime... the pegs are tucked in now... the belly pan rubs first, after the suspension is fully compressed by the g-forces... and if you don't hang off the inside far enough, you're GONNA CRASH, at those speeds.... and when you hang off the inside, your BODY shifts forward... it's a geometry thing........ note the arms status of the rider pictured in your blog piece.... and he's moved forward, slightly, eh? And the inside leg is doing what?... shifting weight to the inside... unless he likes crashing.... Now, look at his outer leg... tell me what you see it doing, besides standing the bike up more vertically by weighting the outside pedal....

Bike Gremlin

Yes, but that is nowhere near the "hanging off" position/technique.

Qute countrary. With the bike more upright and rider compensating for centrifugal force by hanging off, the tyre is pushed more to the side - both the wheel and the tyre taking more lateral load.

This hasn't been my experience. For good steering, staying more in line allows for faster steering and more grip to the tyres.


I'm sorry if I've explained it so poorly that you misunderstood. I have repeatedly stated that it should be executed as quickly as one is comfortable and skillful. And explained what the limits and risks are.


You are mixing fast and abrupt. The latter one is not good. The first one gets faster and faster as one's skill level improves, while remaining smooth.

The steering is (I believe nicely) explained here:
Countersteering - bicycle steering - Cycle Gremlin

Don't take my word on cornering. Test for yourself. All you need is an empty parking lot and a speedo. And crash gear.

Draw a semi circle, about 5 m diameter should suffice. Enter it at 15 km/h, and try to make the 180 turn in line with the bike. Try it with hanging off. See how both things feel. Increase the speed by 3 km/h increments and see which techique causes loss of traction first.

maddog34

look at some pics of riders in corners... including the one on your blog piece.

Bike Gremlin

If you call that "hanging off", than hanging off is the proper way to do it.

maddog34

pretty sure you should go paint a 5M semi circle in the middle of the closest freeway, and practice your turning.

buh bye.

Bike Gremlin

Seems like you have a problem, but it isn't mine. Cheers.