Bicycle Mechanics - can't shift to smallest ring going uphill
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07-31-08, 08:50 PM
I've got friction shifters on my downtube and a Suntour XC FD. I can't shift onto the smallest chainring (24t) when I'm going uphill. I have to be on perfectly flat terrain to shift. the only time I need that 24t ring is in the middle of a big hill. Is this an adjustment issue or something else? thanks!
07-31-08, 08:58 PM
Most likely, you have too much tension on the chain while you are trying to shift. Unlike the rear derailler, the front derailler works on the tensioned side of the chain. In order to derail properly, the chain needs to have some slack in it, enough so that the derailler's spring can deflect the chain enough to cause it to come off the chainring.
If you are having problems getting into your small ring, try shifting into it before you actually need it, i.e. before you are standing on the pedals and barely moving. Shifting habits vary as much as chain lube opinions but if I know I'm going to be needing my granny ring, I'll wait until about in the middle of my cassette, downshift into the granny and then upshift a cog or two on the rear. I've kept my gear ratio about the same but since I'm in the smaller chainring, I've got plenty of lower gears to use. By shifting while I still have a few more cogs in the rear to use, I can always downshift a few more times in the rear if I for some reason start to lose speed and can't get my shift completed.
The other possibility is that your low limit screw is set too far in. This could also make downshifting into the granny ring difficult unless the chain was extremely slack. If my first bit of advice does not work, trying turning the low limit screw out a 1/4 to 1/2 turn and see if that helps. Be careful though because if you go too far, you'll start dropping the chain on downshifts.
07-31-08, 09:20 PM
^^^ Yup, good answer
08-01-08, 12:27 AM
might be the front mech is a bit to high
this gives shifting into smallest cog difficult
new deraileurs have a red sticker on them to set there height.
should be 2 or 3mm above the biggest cog when chains on that chainring
08-01-08, 01:38 AM
Joe's got it right on. If the bike will shift on level ground, then it's adjusted correctly. You have to let up on the chain-tension in order to shift. If you're cranking as hard as you can up a hill, no way will it shift. What you can do is speed up, then let up slightly and shift.
Plan your shifts ahead. Don't go all the way up to the largest cog in the rear while in the middle-chainring and run out of gears, forcing you into a granny-ring shift. Instead, with 3-4 cogs in the rear to go, shift into your granny.
08-01-08, 07:23 AM
[QUOTE=Plan your shifts ahead. Don't go all the way up to the largest cog in the rear while in the middle-chainring and run out of gears, forcing you into a granny-ring shift. Instead, with 3-4 cogs in the rear to go, shift into your granny.[/QUOTE]
Thanks, I'll give this a try and see how i do. I've only got a 6 spd freewheel so I'll shift onto the low ring when I'm right in the middle of my rear cogs.
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