Author Topic: Mtn bike advice  (Read 1067 times)

midwif

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Re: Mtn bike advice
« Reply #45 on: June 02, 2011, 08:53:01 pm »
Someone went out and bought some new tires tonight
My lady bike has a new rear tire.

And I think Jim's does as well.

Wonder who's responsible for that???

The Viking or the bushwacker? ;)
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jim-ratliff

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Re: Mtn bike advice
« Reply #46 on: June 02, 2011, 10:33:02 pm »
Guilty, Your Honor!!  And it was Svend.

Kenda Small Block 8



Quote from: jim-ratliff
Svend:  No reason for guilt. You and I had talked some time ago about the SB8 and I had settled on that as the replacement tire.  Performance had them on sale and I had a coupon for another 15% off, so I bought two for our rear wheels.  2.1 vs 2.0 so a bit wider, minimum air pressure is 30 instead of 35, only 100 grams heavier, and they appear to be rounder and may have a narrower contact patch on the asphalt. Good recommendation, from what I can see.
And now we each have a backup tire.


« Last Edit: June 03, 2011, 10:27:15 am by jim-ratliff »
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Svend

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Re: Mtn bike advice
« Reply #47 on: June 03, 2011, 07:03:24 am »
Hey! Nice!  Not that I wanted you to abandon the Karmas.....sheesh.. ...now I feel kinda awkward.  Destroyer of faith in one's tires.  Shameful!

But, great tires -- lots of guys here have the SB8, and they love them.  Alex has them on her old GT, and I test rode it last night (after doing some rebuilding on the bike) and those tires are sure smooth on the tarmac.  They seem very fast. 

Their grip is supposed to be stellar, and with all the small nubs, I'm sure they will grip the roots and rocks just fine.  I will probably put these, or the Slant Six, on my 29er when the present tires wear out.  Actually, the Bontrager tires on my bike now are similar to the Slant Six, and I like them.

My lady bike has a new rear tire.
  Lady bike?! Yeah, right Lynn.  Complete with girl's top tube so you can get yer skirts and bustles over the bars without wrinkling the taffeta, eh? Or is it gingham you prefer?  ;D  (duck!!!)

Gandalf, we seriously need an animated smiley for ducking a flying rock....

Svend

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Re: Mtn bike advice
« Reply #48 on: June 03, 2011, 08:13:46 am »
Svend:  No reason for guilt. We had talked some time ago about the SB8 and I had settled on that as the replacement tire.  Performance had them on sale and I had a coupon for another 15% off, so I bought two for our rear wheels.  2.1 vs 2.0 so a bit wider, minimum air pressure is 30 instead of 35, only 100 grams heavier, and they appear to be rounder and may have a narrower contact patch on the asphalt. Good recommendation, from what I can see.
And now we each have a backup tire.
Great choice, and I think money well spent.  It will probably give you better control, grip, less rolling resistance on asphalt, and allow a lower pressure when it gets bumpy.  Yeah, and by all means keep the Karmas -- they might work better in spring or fall when things get muddy again.  Now I'm curious to hear how you like the SB8s on the trails.  Let me know....

Did you buy a mini pump too?

jim-ratliff

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Re: Mtn bike advice
« Reply #49 on: June 03, 2011, 08:38:49 am »
No pump yet.  They didn't have it, and nothing they did have excited me.
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bushwacka

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Re: Mtn bike advice
« Reply #50 on: June 07, 2011, 06:13:12 pm »
Hi All....sorry....qui te late joining this chat.  Been on the road again.


BW -- good advice on tubeless.  Might just try that, as my rims and tires are "tubeless ready".  But, what happens if I'm in the middle of the woods, 20km away from my truck, and a tire goes flat? How the heck do I fix it without invoking a one-hour procedure? At least with tubes, I carry a spare and some irons, and can swap a tube in 10 to 15 minutes.  Otherwise, tubeless is certainly appealing -- if nothing else, at least for the weight savings -- 29ers are a tad heavier. 


I still carry a tube on ride that can strand me but have only used it one race out of all my rides race since I have gone tubeless. Quite simply you take the valve stem out throw the right size tube in and your off. I dont know why people dont realize you cant just put a tube into your tire. BTW you do not need anything tubeless to go tubeless. I do it with non tubeless tires, on non tubeless rims sealing it up with a schrader valved tubed cut length wise.

how to do it with out tubeless anything.
http://www.porcmtbclub.org/phpBB3/fix-f7/topic2321.html



The most appealing thing about tubeless isnt the weight saving which it can have but the ability to run lower pressure that not only roll fast, handle turns better, stop and go easy but also ride more plush.

you do need to get way back when decending step sections



A couple of further comments:

On tire width -- I agree with BW, except that before you go wider, you need to check out the weight of the new tire compared to what you're replacing.  Depending on the tire, there can be anywhere from 100g to 200g + difference (1/4 to 1/2 lb!) between, say a 2.00 tire and a 2.20 (check out the specs on the Kenda Karma to see for yourself).  If you're trying to keep the weight of the bike to a minimum, then adding a half-pound to each wheel can really make a difference to acceleration, energy input, etc.  On short, technical rides this is probably fine, and the benefits of a wider tire would far outweigh (pardon the pun) the drawbacks.  OTOH, over a long cross-country ride, that extra weight will really make itself apparent in the last hour of the ride.  Even more so if you are doing multi-day rides back-to-back.  By Day 3 you will wish you had lighter tires -- I learned this two years ago when I rode with my Father-in-law on Vancouver Island -- three days of open-trail XC riding, 3 hours per day, with all-mountain tires that weighed about 800g+ each (~1.5 lbs).  After Day 2 I was ready to go straight to the nearest shop and put on some Kenda Small Block Eights.  Bottom line -- pick the tires that suit where you ride, and for how long.  Maybe keep two sets and swap em as needed:  one for long XC rides / smoother terrain; and one for more rugged terrain / shorter rides.


believe it or not it comes down to wattage, sometime carryng slightly more weight for wider tire can mean your expending less energy because wider tires do roll fast when run at the proper pressure.

Max - FS is actually more efficient even when climbing if its done correctly. There are alot of races held that are won by FS bikes.  I currently dont own a FS bike but love them for everything from XC racing, to all mountain freeride sort of stuff.

Jim - I would run tubeless, then disregard the min pressure recommendation. The min pressure on both of my tire is 30 psi and I run them much lower. Lower pressure goes faster well at least off road, judging by your picture I would have trouble riding fast over those roots at the pressures you run.


Svend

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Re: Mtn bike advice
« Reply #51 on: June 08, 2011, 10:19:52 am »
I still carry a tube on ride that can strand me but have only used it one race out of all my rides race since I have gone tubeless. Quite simply you take the valve stem out throw the right size tube in and your off. I dont know why people dont realize you cant just put a tube into your tire. BTW you do not need anything tubeless to go tubeless. I do it with non tubeless tires, on non tubeless rims sealing it up with a schrader valved tubed cut length wise.

how to do it with out tubeless anything.
http://www.porcmtbclub.org/phpBB3/fix-f7/topic2321.html


The most appealing thing about tubeless isnt the weight saving which it can have but the ability to run lower pressure that not only roll fast, handle turns better, stop and go easy but also ride more plush.

Cool! Thanks for the advice on that.  This is new territory for me, but will definitely look into that.  My LBS sells kits for going tubeless, and the mechanic is a great guy, in his sixties, who will chat for hours if I let him.  He'll sort me out  8)


jim-ratliff

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Re: Mtn bike advice
« Reply #52 on: June 08, 2011, 12:55:38 pm »

BW:

I have to admit, I'm a sucker for "creative" ways of doing stuff, and your "ghetto" tubeless certainly qualifies.  The pictures didn't show up in the link for me, but I get the idea.
The clincher part of the bead isn't clinching on the wheel anymore, it's just sort of a pressure fitting because of the cut BMX tube wrapped around the wheel (sort of like a full width rim strip)?
 
Obviously that hasn't caused any problems for you?
 
Do you normally use wire beaded tires or folded (kevlar beaded) and do you think it makes any difference as far as the tire stretching enough to come off the wheel?  Do you ever run higher pressures with this?


Svend: One of the big advantages of BW's approach is that you don't have a "tubeless" tire valve to remove in order to insert the tube.  Both are just Schrader tube fittings - the tubeless combo is a bit of bubble gum and bailing wire -- but I grew up in Kansas farm country and have a deep appreciation for all that can be accomplished with some bailing wire.
« Last Edit: June 08, 2011, 02:07:47 pm by jim-ratliff »
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bushwacka

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Re: Mtn bike advice
« Reply #53 on: June 08, 2011, 08:50:50 pm »

BW:

I have to admit, I'm a sucker for "creative" ways of doing stuff, and your "ghetto" tubeless certainly qualifies.  The pictures didn't show up in the link for me, but I get the idea.
The clincher part of the bead isn't clinching on the wheel anymore, it's just sort of a pressure fitting because of the cut BMX tube wrapped around the wheel (sort of like a full width rim strip)?
 
Obviously that hasn't caused any problems for you?
 
Do you normally use wire beaded tires or folded (kevlar beaded) and do you think it makes any difference as far as the tire stretching enough to come off the wheel?  Do you ever run higher pressures with this?


Svend: One of the big advantages of BW's approach is that you don't have a "tubeless" tire valve to remove in order to insert the tube.  Both are just Schrader tube fittings - the tubeless combo is a bit of bubble gum and bailing wire -- but I grew up in Kansas farm country and have a deep appreciation for all that can be accomplished with some bailing wire.

In all honesty IMO this way works better than the Stans kits way because its seals up non tubeless tires better.  It doesnt work better than actually tubeless rim which while spendy are a ton better for doing this and you dont have to do it the ghetto way. i have literally 1000s of miles on this setup on various rim/tire combination on trails all over the country. The failures have been few and far between and when it fails I just put a tube in it. On shorter rides where I cant get stranded in the wilderness I dont carry tubes with me anymore as my chances of flatting on nearly zero.

It doesnt matter about the wire vs folding just be very careful of using ultra lightweight XC tires, because some of them  just do not  work. For instance the standard Small Block 8 can be a bear to seal up  but the tubeless version of it works just fine. 

http://www.epicski.com/forum/thread/95039/how-to-do-ghetto-tubeless-for-finndog-and-anyone-else-who-wants-cheap-tubeless-tires

those picture work in that thread.

I use schrader valve because it easier to seat the bead with schrader valve and it also means that any old gas station pump will work to seat the bead with out an adapter. If you use 'tubeless" tires you will most likely be able to seat the bead with a floor pump. Presta valve do work and I have the same set up on my Single Speed cross bike and my road bike with prestaa tubes albeit running a tubeless hutchison bull dog cross tire.  I did not want to drill out my skinny cross/road rims.

as for tube size here is my list

26 inch rim = 20 BMX tube
650B = 24 inch MTB tube
29er = 26 inch MTB
36er(yes they do exist) = 29 MTB



editted to add this

you can not run higher pressure with tubeless. 35 psi is the max I go with non tubeless tires because of the risk of destroying the bead of the tire and also blowing it off the rim, You can run higher with tubeless tire....but the point of going tubeless is to run a lower pressure with out a risk of flatting.
« Last Edit: June 08, 2011, 08:54:25 pm by bushwacka »

jim-ratliff

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Re: Mtn bike advice
« Reply #54 on: June 08, 2011, 10:05:24 pm »
Josh:

Thanks - got it.

BTW, did my first little ride on roots and rocks with 'only' 30 lbs pressure front and back. Could feel the difference. Even bought a pressure gauge for presta tires.

Even at 30 my sidewalls were barely soft. I'm learning, but moving slowly.
« Last Edit: June 08, 2011, 10:08:06 pm by jim-ratliff »
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bushwacka

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Re: Mtn bike advice
« Reply #55 on: June 09, 2011, 06:51:41 am »
yeah and a tubeless tire will be more supple at 30 psi.

The deal with running a tire with a tube in at a lower psi is it can pulled off the rim easier in turn because the bead is not as lock on it would be if it were tubeless.

Svend

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Re: Mtn bike advice
« Reply #56 on: June 09, 2011, 07:01:27 am »
Josh, just curious -- have you played with pressures in 29er tires, with tubes? I run about 35 to 40 for hard packed flat gravel rail trails, and 25 to 30 for in the woods.  Terrain of latter is mostly hard clay, some rocks, roots, ruts, occasional sand and loose coarse gravel.  Pressures seem fine for both types riding.  But interested to know what your experience has been on that... Thanks.

Another question:  what bar width do you find optimal for a 29er? I have a low rise, about 685 wide, but was thinking of swapping for a flat bar, either same width or a bit narrower.  Want to improve handling, and extend my reach just a wee bit.  I'm thinking narrower may not be better....correct?

Cheers....
« Last Edit: June 09, 2011, 07:03:07 am by Svend »

midwif

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Re: Mtn bike advice
« Reply #57 on: June 09, 2011, 09:29:06 am »
Quote from: bushwacka

The most appealing thing about tubeless isn't the weight saving which it can have but the ability to run lower pressure that not only roll fast, handle turns better, stop and go easy but also ride more plush.

you do need to get way back when decending step sections





Ye Gads!!
Ain't doing that kind of riding in the near future. Probably never!!
Looks awesome young Bushwacka. 
Lynn
« Last Edit: June 10, 2011, 11:35:40 am by jim-ratliff »
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bushwacka

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Re: Mtn bike advice
« Reply #58 on: June 09, 2011, 09:45:17 am »
I dont run tubes ever. On my own personal bike I put a hole into a tire during a long race, put my tube in it and flatted the tube with in a couple miles at 30 psi.

last weekend I demoed a anthem X 29er and the tubes tires on were a pain in the ass. Giant had them inflated to 38 psi which rode like ****. It was rough, had no grip, and rolled so slow because it was boucing off everything. I lowered the pressure to 28 psi. It rode better in a straightline but the tire rolled off the rim, and I pinched flatted the rear tire in rock garden at high speeds.

For me I simply can not ride the way I want to on tubed tire. I either have to run a high pressure and suffer though lack of performance, or run a low pressure and for sure flat it.

There is nothing better about a tubed tire.

bars and stem are personal thing. It has nothing to do with what size your wheels are.  it does have to do with your trails, what your use to, what your willing to get use to, your bike size elect elect.  I personal hate being in a really long position.  I use a 70 mm stem with a very swept back flat 740mm bar.  I also use ergon's and bar ends.

Improving handling? what do you need improved?

extending reach? why do you want your reach extended?

a slightly wider bar let you leverage in turns and tech areas better, also on Single speed it let me leverage on climbs better.  You have to use a shorter stem though because your reach effectively gets longer as your bars get wider.



the bar ends let me get far forward while climbing while still letting me run my short stem, they are also quite handy on 40-50 + miles rides to keep my hands from getting fatigue on road sections.



the shorter stem lets me loft the front end alot easier and make it easier to ride trails aggressively. Alot of XC guys are now shorting their stems quite a bit even on the World Cup, but I think long stems anything 100mm and over are passe' and actually hold people back when riding singletrack.   

again using what I use on my bike might not work for you. It could work for you and feel pretty awkward at first. You could extend your width a little bit and that should improve your handling and your lenghten your reach. you would be hard press to see a narrow long set up at any XC race these days. People just didnt know any better back in the day, and the kids these days like comfort and performance. 


jim-ratliff

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Re: Mtn bike advice
« Reply #59 on: June 09, 2011, 11:17:13 am »



BTW, I bought the Ergon grips for Lynn and I -- I agree with BW, they are wonderful.
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