Old 01-10-19, 05:19 PM
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Join Date: Oct 2018
Location: SE USA
Posts: 123

Bikes: 2018 Fuji Jari 1.5, 2019 Trek Domane SL5

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Originally Posted by Steve B. View Post
Some thoughts;

1) It almost sounds like a compatibility issue between the Oval crank and the 5800 system, maybe the positioning of the crank is not to a Shimano spec. I was wondering if a mismatch is causing the big ring to change the entry angle of the chain to the lower jockey wheel and possibly pulling the rear derailleur in such a way as to exhibit the "too much cable tension" symptom. Except many of these bikes have been sold with these components installed so that "maybe" rules out compatibility as the problem.

2) Shimano does not show a compatibility between the 5800 system and 46/36 rings, as noted here: 2018-2019 SHIMANO Product Information Web

3) I applaud the OP's desire to learn and do your own work, but sometimes the lack of experience is going to drive you nuts as you try to troubleshoot. I build up bikes from frames but on occasion have to head to the shop for some expert help. My local guy caught that I was attempting to use a 9spd system with an 8 spd. triple crank, was why the chain was dropping between rings when I shifted to a smaller ring. I would never have thought of that as I had no clue Shimano had changed spacing between rings.

4) It really sounds like a cable tension issue. Maybe a housing is not seated correctly ?, got moved when you disattached cables ?, thus some friction at certain points in cable travel ?. Maybe just enough dirt in the system to cause mis-shifts in that combo ?, even though the bike is only a few months old ?, been riding gravel and dirt ?.
Yes we have been riding on dirt and gravel a few times but mainly on the road though, itís been doing this since we bought the bike. It is a cross bike so maybe thatís the issue here. We just didnít have time with the holidays to bring it in before they announced their closings. It is an older model so Iím sure it was sitting around for a while and Iím wondering how many of these particular models sold have had similar issues. Maybe Iíll do some google-fu this evening to see if anyone else has had similar issues.

My next troubleshooting step was to replace the cables since theyíre not Shimano and maybe werenít lubed properly during installation. Or maybe it just been on too long despite sitting on the shelf for so long and now itís become an issue? I know it could be any number of those things and truth be told Iím willing to fork out a few bucks to replace a few things just to start fresh. Since we donít have support I donít have to worry about voiding any sort of customer satisfaction guarantee etc. lol
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