JEC7

Hey guys,

Just bought a new bike (Specialized Hardrock 26 Disc) and it now has nearly 20km on the odometer.

I've discovered that I can't stand up and pump without (what I'm assuming is) chain-skipping.

At first I assumed that it's because I'm heavier than the standard bike rider (150kg), but I just thought I'd get a second opinion in case something is wrong mechanically.

So is this happening because I'm heavy or is something wrong?

Thanks

ARider2

The bicycle should not do that. Given that it is a new bike bring it back to the shop you bought it from and have them fix it. Probably just a minor adjustment of the rear derailleur.

goldfinch

Agree with ARider. You could try turning the barrel adjuster on the rear derailleur counterclockwise to increase tension to see if that works. But given that you have so few miles on it I would bring it in to your LBS and have them adjust it.

Mark Stone

I agree with goldfinch and Arider2, the bike needs to go back to the lbs.

JEC7

Damnit! Pity the LBS is 200km away...

rdtompki

With new components what you're experiencing is very often a mis-adjusted rear derailleur. The chain isn't really skipping on the cog, it's catching on an adjacent cog momentarily. Take it back to the LBS; they can adjust it in 10 minutes. Pay attention, ask questions and you'll soon be able to make these minor adjustments yourself.

PhotoJoe 

Cables stretch a little when they're new, which changes shifting behavior. LBS should have told you to bring it back in a month or so for an adjustment anyway.

bigbones73

Plus 1 on the LBS 30 day checkup--my shop did the checkup for free.

sstorkel

If the shop is too far away to be convenient, derailleur adjustment is actually pretty easy to do yourself. You can likely find the instruction manuals for the components on-line, if they weren't provided with the bike, or you can check the Repair Help section of the Park Tool website. Adjustments are easier if you have a work stand or someone to hold the rear tire off the ground while you turn the pedals. As goldfinch indicated, the OP probably just needs to adjust the cable tension via the rear derailleur's barrel adjuster.

TrojanHorse

+1 to everything sstorkel just said. Especially if your LBS is not so L.

Mr. Beanz

Yeah, very easy.

Tunr the barrel adjuster till the chain starts to hit the next biggest cog (will start making a rattle noise). Then back it off about 1/4 turn. That should put you right in the ballpark. Then make small turns till it runs quiet, Bam, you're done!


WHATEVER YOU DO, DON'T TURN ANYTHING WITH A SCREW DRIVER!!!! The limit screws etc.should be set when you bought the bike. They don't (shouldn't) change so don't "screw" with them.

I won't be surprised if you turn the barrel adjuster 1/2 turn and it simmers down.

JEC7

I think I might just give this a shot.

Thanks for all your help, guys!

goldfinch

You should have the rear end of the bike up off the ground (maybe someone holding it up or rope it through your rafters or something) so you can easily spin the pedals and run through the gears as you adjust the barrel adjuster. Shift to the large chainring in front and the smallest cog in the back. Use your ears and listen. Turn barrel adjuster counter clockwise until you hear rattling. Then back off a quarter of a turn. If it doesn't rattle you are good. If it still does, back off some more by turning clockwise. Go up through the gears, listening and adjusting.

Park Tool has good instructions on its site, look for Indexing adjustment for the rear derailleur.

Eh, I guess I said what Beanz said. Missed his post. He is right. Don't mess with the screws!

cod.peace

And if that doesn't do it, grease the cables where they pass under the bottom bracket...tip from Sheldon Brown's website, works if it's autoshifting to smaller cogs when you stand up.

RichardGlover

km? kg?

What the heck is that? Use real measurements, lol. (j/k)

JEC7

Thanks guys, I twisted the barrel adjuster a little and the problem seems to be fixed.

I'll still take her in for a checkup next time I'm near the not-so-local BS.

Don't even get me started!

adrien

...make sure the wheel is fully in the dropouts. To do this, open the skewer with the bike on the ground, push down, center the rim between the brake padds and tighten again. Tighten so it needs some effort to close, but doesn't leave a mark on your hand.

If you wheel is in crooked, that can cause the chain to skip.

jerrduford

Try taking it back to the LBS and have them adjust the derailleurs and cable tensions. If this doesn't fix it or if it still tends to slip, but only while standing, I would give your chain a good look. My bike is still sub 1k miles and sometimes the chain slips into a lower gear when I'm really moshing on the peddles if the chain is dirty / over lubed. If the chain has tons of debris or is slippery in oil, try drying it off completely with a towel then reapplying a really thin layer of grease. if it only tends to happen in lower gears, but not necessarily in the lowest gear (which would suggest a min problem with the derailleur), I would especially lean towards the suggestion I've given.

good luck!