Talking tyres... again

[Jacomus]

"Tally-ho chaps - I'm going in" ... On yet another tyre puzzlement.

Situation - Std geometry roadbike, running Michelin P2Rs in 25c

I have just finished some fettling, where I have moved my saddle back by 60mm, and slightly changed the angle of my bars (rotated slightly upwards, with a downward movement of the levers so that they remain in the same place relative to my fingers in the drops, but are further forward from a saddle to bars perspective.

I did this, after starting to wonder if my seeking a more compact position on the bike, was actually making it more uncomfortable, not less. So I have stretched myself out to where I feel is comfortable, and initial rides report that everything is ok... so far, time will tell.

Problem - You may be wondering what this prattling has to do with tyres...

well, I am ludicrously sensitive to tyres, and much much money wasted has led me to finalise on the P2R in 25c as my favorites (until I can get my hands on P3Rs).

There is only one fly in the slightly more stretched out ointment - it seems to have changed the way the bike feels when cornering. Specifically, I have noticed a heart-in-mouth sensation of them walking i.e. sliding outwards, very slightly, in stages, round some local corners I knew well.

This is on dry roads, and I am hoping people have some ideas as I'm fresh out. 

Pressures: Rear 6.5bar, Front 5bar, I weight 75kgs and the pressures make each tyre deflect roughly the same amount when I'm on the bike.

Could it be I need to up pressure slightly, or is it because the roads were salted with Surrey County Cuntcils stupid idea of cost saving by using Sureseal additive to salt, which makes roads as slippery as when wet, but when dry, for about a week after they use it. Maybe I need to get use to distributing my weight slightly differently in this new position. ARGH!!! I'm very confused. 

[rogerzilla]

I found the opposite with Vredestein Fortezza TriComp - they give a sharper turn-in.  Fabulous grip.

[Biggsy]

J-r_G, I suspect either you are imagining that the tyres are going sideways, or you are taking these salty corners too fast.  The pressures are rather low, but pumping them up will decrease grip, not increase it.

7 to 8 bar would give you more speed on the straights.

[Jacomus]

Hmm, maybe so Biggsy, and I don't think I need more go on the straights, I'm happy with my speed/effort ratio.

I certainly hope it is as you say, overenthusiastic cornering. Bah bah bah humbug. I guess that could also be why I didn't notice it when I was out earlier, as it was really sunny, and the road I did all the fast work didn't show any salt residue.

[mrcharly-YHT]

If the pressure is a bit low, won't it make the tyres feel squirmy when cornering?

[Jacomus]

Maybe thats true too, you see my dillema!

I have tried "contact us" on Michelin's website, but been ignoored twice 

[Biggsy]

I've just had a feel of a 25mm tyre at the pressures you're using and I reckon with your weight they're high enough to prevent squirming.

But still I think it wouldn't be bad idea to stick 0.5 to 1 more bar in each tyre.  Even if you don't want more speed on the straights for the same effort, it will make the tyres last longer.

[MSeries]

60mm move in saddle is quite a lot. How long is your stem ? Your position relative to the BB has changed quite a lot, i am surprised you don't feel it. In what way was it uncomfortable before ? For how long do you ride ? I suppose there could be the possibility that you are now placing more weight on the back end of your bike as you are now closer to the rear axle and hence the contact patch of the tyre. Not sure what this means in terms of slipperyness. I think it'll be due to the grime on the roads sucking the moisture out of the air and leaving the road slippery. I am experiencing the same thing here. Compounded by the fact I was off the road for 5.5 months and I am still not fully relaxed, my new GP4000 feels awful.I have used GP3000s on other bikes and they were good but that was on un gritted roads.

[gonzo]

There was something written on weight weenies about the grip taking a while to kick in on corners for pro-race 2s. Apparently they've solved it with the 3s.

[clifftaylor]

I'd agree that a bit more air in the tyres would be a good idea. More than that though, I'd also agree about the 60mm rearward movement of the saddle - it's a lot (and you'll need to drop the saddle to keep your leg extension the same), and will make a big difference to the handling, as there will now be quite a bit less weight over the front wheel, with a tendency to understeer.

[Jacomus]

I think that is partly it - I am further away from the front wheel, but my bike is now set up as "normal" instead of all bunched up. 60mm is completely wrong - I think I must have had some brain failure when I wrote that, I think the rails are 60mm long, and I moved it back 15mm!  oops!

I have been out doing more testing today, and think I have pinned down why it feels so weird - where as before I was so far over the nose of the bike, she literally fell into corners, and I often needed to pressure the outside bar to keep her from falling over to the inside. Now cornering is done normally with countersteering all the way through.

I caught myself falling into what was a habit I didn't realise I had - I would countersteer to get the bike leaning into the corner, but would have to correct the fall by steering a little, and I bet this was adding to why I have felt nervous in corners, especially fast ones that require a lot of lean, because I was always fighting the bikes desire to fall over. Now I have moved my weight to where the bike was designed to carry it, everything has becomre more stable.

The walking I experienced I think was partly due to slimy roads, but more down to my subconcious steering correction that would make the bike sit up a little, then I would have to push it back down.

It will take me some more time to get used to this position, but I think (hope like hell) it is going to turn out more comfortable for me, and yield handling benefits.

We shall see...

[gonzo]

Pro bike kit have just sent me an e-mail to tell me that they've got PR3s this weekend at £20 thus they've actually arrived.

[Fab Foodie]

Pro bike kit have just sent me an e-mail to tell me that they've got PR3s this weekend at £20 thus they've actually arrived.

They've been at  Parkers (£20ish) and Wiggle for a while now.
I fitted mine yesterday and had a splendid 40 miler on them this afternoon.
Well...they're a proper 23c size rather than the almost 25c that the old 23 PR2's were.  They sit very neatly on my Reynolds Alta-Race rims.  Handling is a bit faster than the PR2, grip seems very confident from day 1.  Roll very well, particularly at higher speeds where I think the narrower profile helps i.e 20mph ish.  Do feel slightly different to PR2's, but can't really explain...PR2's whilst quick always felt a bit balloony if that makes sense, the 3's just feel tighter, sharper steering, make you want to lean the bike harder.  I'm 13 stone and ran 105psi rear with 100 front.  Bump absorbtion I thought was good a that pressure.  Will run 110/105 psi at club-night on Tues.

Early days, but I really liked them, I thought the 2's were a hard act to follow, but Michelin seemed to have managed it!

[KidJambo]

Maybe thats true too, you see my dillema!

I have tried "contact us" on Michelin's website, but been ignoored twice 

Not good - Michelin pride themselves on not losing touch with the little guys out there so apologies for that!

For those of you have not yet met me, I am the sales & marketing manager for Michelin cycle products in the UK & Ireland (and from the start of this year, Scandinavia also - must be doing too good a job I feel and wonder what additional market and workload they'll give me next!!) and the person who any cycle related enquiries through the website in English from wherever in the world get sent to - I think there must be a problem in the system. If you want to ask any questions then feel free to post on here or message me or email me directly at andy.james@uk.michelin.com - always happy to deal with serious cyclist with serious questions rather than the usual requests for stickers!

[mike]

ooh - are there stickers?

[KidJambo]

ooh - are there stickers?

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