Opinions on Shimano 105 10-speed STI transmission ??

by hill_climb   May 28, 2014  

Hi all,

Just returned from a 170km mass-start event which was on a very hot day (25DegC+ temps). I had done all my prep work ahead of time, including getting the bike transmission adjusted well. Cables stretched, mech's lubed, chain cleaned and dry lube'd, a lot of grease applied over the plastic cable guide under the bottom bracket shell, etc.. Everything was working well. After about 4 hours in, the shifting started to get sluggish with no down shift at the start of some climbs. All very frustrating.

The bike is about 5 months old and everything is in pretty much as-new condition. I have found that after about one month of ownership the initially fault free operation of the transmission would start to get sluggish. I put this down to the new cables starting to stretch so took care of that.

This is my first 10-speed setup. Its 105 STI shifters, Tiagra front (50-34) and 105 rear (11-28). Honestly, I am finding it to very temperamental in general with fault-free shifting only lasting for about two or three training rides. Basically, I need to look for a fix for the next event. Short of just buying new equipment, what should I be looking at in terms of setup and maintenance? The way things stand, I don't have confidence with this for anything beyond 4 hours or so. Could there be something that needs to be looked at with the STI shifters? They never seems to be mentioned when there is talk about gear change issues? I say this since in addition to the rear issues, I found that the front downshift to the 34 ring would need an almighty push as a light click would do nothing later-on on the ride.

many thanks,
Ken

By the way, I don't want to use the C word, but I am a fan of a certain Italian component manufacturer

11 user comments

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Hmm, never heard of a problem with 105 shifters. Are you tightening cables off enough on your derailieurs? Are your outer cables properly seated in the frame and in the shifters?

posted by bashthebox [637 posts]
28th May 2014 - 15:19

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It sounds an unusual issue to degrade so quickly but one thing I would do is to stop greasing the cable guide under the bottom bracket. It will only attract grit and dirt as you ride, they generally work better 'dry' or with a very light lube. If the cable sticks here then this might explain why the front mech is reluctant to shift onto the smaller ring.

It sounds most likely to be a cabling problem though. You don't say if you are lubricating cables but again, they tend to work better with whatever lube or teflon type coating they came with, If you flush this out with spray oil it doesn't always make things better.

If you have the 5700 series 105 levers with the cables under the tape then they can suffer from having the cable bend tight around the inside of the bar. If it persists then you could replace the stock shimano cables (which on the whole are not bad) with some aftermarket ones like Jagwire for example.

One final thought, inner cables do not stretch as such, what tends to happen is the outer and ferrules can compress and generally settle into the cable stops resulting in slack. If you are slackening off cables to oil them then each time you take up the slack then you are inviting movement and then re-settling.

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posted by joemmo [786 posts]
28th May 2014 - 19:35

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As per joemmo, never had any issues with 105 10speed or Ultegra 10 speed (essentially the same shifter but a carbon lever).

I wouldn't put grease anywhere near the cables on my bike (brake or gear), but I would use a light dry lube to minimise the friction and work as a corrosion inhibitor. If its both front and rear gears then it could be the grease around the bb where both cables pass.

Cable outers can also shift slightly under bar tape through riding or in the event your bars get too twisted e.g. lifting in/out of a car boot etc.

I'd get new cables (inners and outers) professionally fitted with new bar tape and if its done properly that should sort any issues.

posted by mtbtomo [44 posts]
29th May 2014 - 13:11

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I had a similar problem it turned out my outer between the frame and rear mech was too small to it was causing allot of resistance try running a new cable with what my mechanic called a f**k off outer Big Grin

If someone's faster than you there obviously not going as far

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posted by Charliegr555 [16 posts]
29th May 2014 - 15:19

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Thanks everyone. The front and rear mech's have been sprayed with lubricant, and that did seem to work well, not a long term solution though. This talk of cable routing does make me think though that there may be an issue there. Over the last five months I have gradually lowered the bars by what is now 25mm, as well as replaced the stem with a 10mm shorter one. The cables coming out of the bar tape now have noticeably more bend on them and there is an obvious bend on the outer as it terminates on the down tube.

Going to look into that and shorten the outers and see if that solves things. Thanks.

posted by hill_climb [7 posts]
29th May 2014 - 21:24

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be careful when you shorten the outers, to short is as bad as too long, you need good smooth curves, this includes at the rear mech, depending a the frame routing sometimes the outer at the rear mech looks way to long, but you really need that smooth arc

ditto everyone about lubrication, it will cause more problems in the long run, use decent outers like Jag or Shimano's own.

If you are going to get new cables done at a bike shop, make sure they know what they are doing, just because they have the tools, don't mean they know what they are doing as anyone that been into the the big Orange shop will attest to, and for the price some places charge, you can buy the right tools, watch a few decent videos like the ones from Art Cycles or Park tool and you are set for life

posted by jason.timothy.jones [303 posts]
30th May 2014 - 9:18

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clean any grease from the bb guide .... a little spray teflon is about all that needs
as anymore attracts dust/dirt/debris from the front wheel making changes
crunchy at best .....

still on the 3rd switch-back of Bwlch !

posted by therevokid [697 posts]
30th May 2014 - 10:22

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As many have said, a 10 speed 105/tiagra mix has been faultless for me in the past. I did 3000 miles on that set up last year in all weather conditions and it behaved pretty much faultlessly. I didn't lube the cables once in that time - all it needed was chain lube and occasional gear tweaks as the cables stretched. Tight radius bends in the cable routing definitely sound like they could be the problem.

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posted by tom_w [85 posts]
30th May 2014 - 10:29

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When my (Tigra) 10 speed transmission was new, I found it needed frequent adjustment over the first 1000 miles or so, as the cable took a while to bed itself in - and then after that it was suddenly fine and reliable.

posted by Must be Mad [39 posts]
30th May 2014 - 11:43

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As @hill_climb says, a tight angle around the bars under the tape can be a real problem. Some bars have way less than the recommended minimum 80-100mm internal radius. Sometimes they are installed without Shimano's recommended plastic cable tunnel. It's also better to run the gear cable on the front, next to the brake cable, than around the back of the bar. A tight cable radius made my 6700 setup (virtually identical to 5700) initially absolutely horrible. The rear mech would take 5 turns of the crank to get to the correct cog. Really annoying!

Also make sure when you put the new cables on, to flare out the hole at the end using the tool on the side of the Park cable cutters, or a spare bit of wire. A tight cut on the end of the inner can produce a dreadful grating cable motion. And if you've moved the bars, you'll find that you need to recut the cables to get the best large radius on the cables leading to the down tube. Best if the two gear cables cross under the stem and enter on the far side of the downtube, thus crossing inside the downtube to exit on the correct side of the bottom bracket guide. If you see what I mean!

posted by drmatthewhardy [303 posts]
30th May 2014 - 22:13

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Just posting to say that the issue is now resolved! It was indeed the long length of cable between the exit under the handlebar tape and the down tube, caused by the bars being lowered over the past few months. Thanks for the comments on that. The bike came from the factory with Jagwire cables but I picked up a set of Park cable cutters and re-worked the cable outers. Everything is working great now after a 50 miler this afternoon.

A big thank you to all.

posted by hill_climb [7 posts]
6th June 2014 - 21:10

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