Shimano 105 Shifters

LockyHK

Hi All,

I have recently purchased a new Cannondale Synapse Carbon 105. I can't fault the bike itself i think it's great but it has me wondering whether I need to quickly start updating some components on it.

I've found on almost every ride I have had to stop at some point and fine tune the rear derailleur via the barrel adjuster to stop the chain skipping cogs or allow me to get into the lowest gear. On a rather strenuous hill climb the chain slipped from the lowest gear to mid range on the cassette and nearly saw me kiss goodbye any future plans of fatherhood.

I have taken it back to the bike shop and the mechanic has indexed it perfectly but sure enough on the next ride the same problem occurs. The chain is obviously brand new and correctly sized and fitted, so it has me wondering whether i'm just expecting too much from the 105's and an upgrade is necessary or you think this is faulty unit or I should be looking elsewhere for the cause?

P.S I always keep the drive train meticulously clean and properly lubed.

Thanks in advance,

Locky

scottishgeek

You should certainly be looking elsewhere for the cause as 105 should not be like that. Mrs SG's community bike is an aluminium Synapse with 105 and it goes for months without requiring indexed.

For starters I'd say look at the cables, both inners and outers, for signs of rough ends or anything that could snag a cable. Check the low limit screw is not set a smidge too far in

frisbee

If it is jumping from the lowest gear to the middle then it isn't just bad indexing, sounds like something is slipping or moving.

LockyHK

Ok thanks guys back to the drawing board I suppose!

Anonymous

Check the rear wheel is sat in the dropouts correctly. I have had this same problem and the wheel not being central was making the lower gears slip as the larger rings wobbled more as they turn causing the chain to skip.

LockyHK

Maglia Rosa wrote:

Check the rear wheel is sat in the dropouts correctly. I have had this same problem and the wheel not being central was making the lower gears slip as the larger rings wobbled more as they turn causing the chain to skip.

It's funny you mention this because each time I have taken the back wheel off to give the bike a proper cleaning, after reconnecting the wheel, no matter how certain I am its seated correctly the adjuster barrel always needs some small adjustment on the work stand to have the chain stop "jumping". Apparently this is relatively common but it seems odd to me you should need to do this.

SME

frisbee wrote:

If it is jumping from the lowest gear to the middle then it isn't just bad indexing, sounds like something is slipping or moving.

My thoughts too.

I recently bought a Domane 2.3 that has 105 running gear and have had no problems. It did start getting just the slightest bit 'chattery' but the 6 week checkup sorted that once the cables had stretched/bedded in, and there's been no problems since.

I might also be looking at the ends of the cable outers to see if they're 'crimped' when they were cut to size - the inner cable could be dragging causing the symptoms you describe.

But at the end of the day the shop should be sorting it, and if it's jumping gears to that extent it's not fit for purpose.

Good luck,
Steve

Giraffoto

Check also that your derailleur hanger isn't bent - that can cause a lot of issues while being hard to spot

slowbike

LockyHK wrote:

It's funny you mention this because each time I have taken the back wheel off to give the bike a proper cleaning, after reconnecting the wheel, no matter how certain I am its seated correctly the adjuster barrel always needs some small adjustment on the work stand to have the chain stop "jumping". Apparently this is relatively common but it seems odd to me you should need to do this.

No it's not!

I've never had to adjust it after just re-seating the back wheel - that's on all our bikes - no matter the groupset/shifters - from the cheap_as_chips Shimano 2300 through 105 to Ultegra ...

If you're constantly having to adjust it then the cable is slipping somewhere ...

Anonymous

Could be the cassette lockring isn't properly tightened up?

LockyHK

OK thanks all I'll take it back to the shop and have them sort it. At least I have some ammunition now that all is not ok!