jonathan180iq

I was swapping out my tires lastnight and I let the chain get away from me and it lost its place on the sprockets. I positioned it where I thought it should go and ever since then, I've been having some wierd shifting problems.

Can someone please verify that (LOW,1) would have the chain positioned with small chainwheel-large rear sproket.

Also, (HIGH,5) would be large chainwheel-smallest rear sprocket.

Is this correct? I may simply need to adjust my derailluers.

Cheers,
Jonathan

sydney

I doubt it.... The chain will find it's place on the sprockets as soon as you pedal.

Matt Gaunt

I never get the chain on the right rear sprocket - it's unnecessary. I just make sure the chain is somewhere near the higher (smaller) cogs so that the wheel can get past the rear mech easier.

The chain position cannot vary because the gear cable hasn't moved. It must be the mech that's slightly out and that has nothing to do with taking the rear wheel off and replacing it as far as I have seen.

shane45

...unless he's bent the derailleur hanger in the process.

neil0502

Right ... of course.

After a mechanical fix like this, it's never a bad idea to lift the rear wheel with one hand, while twirling the cranks a couple times with the other. This gives the chain a chance to find the 'proper' gear without putting stress on the drivetrain.

jonathan180iq

The derailluer hanger and all the bits are not damaged. I took car not to knock any of those things. I'm just concerned with the chain placement. I've set as best as I could and, if nothing else, I have enough useable gears to do what I need to get home.

My concern lastnight came when I was trying to shift into the higher chainwheels.
I couldn't get past mid gear. So, I loosened the derailluer adjusting screw as far I could. I can smoothly get into HIGH gear now, but I can't get back down to LOW. Again, the best I can do is mid gear. Anyone have any ideas?

Cheers,
Jonathan

neil0502

Changing the tires shouldn't automatically necessitate derailleur adjustment. Needlessly adjusting a limit screw, however, will.

Time to go back to basics. Go to ParkTool.com, look up repair help for front and rear derailleur, and go through the adjustment process step by step.

Be patient and methodical ... don't skip steps. Shouldn't take you long.

jonathan180iq

I didn't consider it needless. The bike wouldn't shift into the higher chainwheel. So, I adjusted accordingly, by loosening the HIGH adjusting screw. This problem may come from the fact that I'm doing all this on a $58 special from Wal-mart.

All of my rear shifts are fine. I'm just having trouble getting into all three front gears.

sydney

^^^^...Well, there is a methodology to front adjustment and you have to do it right by starting at the beginning.If it was right before the tire change,then tire changing should not have affected it. Fiddling like you did usually just shifts(no pun) the problem somewhere else as you have found out.

ppc

I had a bike with a similarly weird problem: each time I'd take the rear wheel off and back on, the derailleur would be off a bit. I traced the problem to a flexy dropout/derailleur hanger that flexed inboard the tighter adjusted the QR.

Try this: undo your QR lever, undo it half a turn, re-tighten it, see if anything changes. Look at the derailleur when you tighten the QR, see if it moves. If it does, you'll either have to "remember" the QR tension (a good rule of thumb is having the lever become tight about half-way closed) or readjust the derailleur a bit at the shifter each time you take the wheel off.

neil0502

Your comment reminds me of another silly possibility, but one worth checking: is the rear wheel absolutely centered -- and all the way into the drops? If there's an angle there, that'll definitely throw off the shifting.

jonathan180iq

This was something that I was worried about. The wheel/tire look straight enough and I have gone for 2 rides with no problems; the gears that work are acceptable. I just don't have my easy gear. (I'm actually increasing my average speed by leaps and bounds, since the tire swap and the funny gears) Anyway, I did notice that the "axel" doesn't sit as far back as it did before. I can tell from the circular paint scratches that were left from the original bolts.

The bike isn't nice enough to have quick release.

For $58, I'm very satisified. I trek a little more than 12 miles from work-school-home. And, on the return trip, 9.1 miles, I'm averaging 59 minutes. That's a notch over 9mph avg. I don't consider that too bad for a mountain bike with street tires, lighter handelbars and a nice seat.

jonathan180iq

I didn't adjust anything until after I realized that I could no longer shift into H. That wouldn't have made any sense.

neil0502

This could be altering your chainline and degrading your shifting. I'd loosen the bolts and slide the wheel back snug against the "stops." In other words (iq=180? then you get this ): if the dropouts are vertical
___
|X|
| |

... then make sure the axle is snug against the top. If the dropouts are horizontal

---
|X
---

... then make sure the axle is snug against the back.

Try the front der after that. If it's still off, I'd check the parktool FD adjustment section.

jonathan180iq

I finished reading over the ParkTool stuff early this afternoon. My dropouts are horizontal. I'll just slide 'er back a bit. I'm having to all this with just two hands and no bike stand, so it's been a pain.

180iq is from a liscense plate in the movie "Sneakers". I thought it was "cute".

Thanks for your help,
Jonathan