Cannondale SYNAPSE Seat Post Will Not Insert

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bigcalves
Posts: 73
Joined: Thu Nov 04, 2010 3:29 am
Location: Boulder, CO

by bigcalves

I know this is not a weight weenie issue, but there are a lot of smart people on this board, so here you go. Any help would be appreciated.

I am putting together a 2016 Cannondale Synapse as an extra bike, it comes stock with Di2, and the Cannondale seat post is set up to hold the battery internally. I have built 4 different bikes with Di2, all run internally and no issues. I cannot get the seat post to slide down into the frame. It will go down a little and then get stopped there. I have put some pressure on it and it really does not go further. When I backed it out I noticed markings on the Di2 cable, it would appear they are getting pinched in there. I took the whole seat bolt assemble out (the bolt and both wedges), plus I also took out the water bottle bolts, to ensure the post had as clean a run as possible, just to get it in there. It helped a little, but the post did not slide in there well. I gave it more pressure, I got the post fully in, but it did not feel right. I pulled it back out to try it with the bolt and wedges and when it came back up the Di2 wire was shredded. It still works, but was rather concerning. Before anyone ask, yes I used carbon paste on the post and on the seat bolt parts.

My next step is to go see a dealer and get their help, but I wanted to know if anyone had seen this issue, or had any advice. Thanks.

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rpowell
Posts: 59
Joined: Tue Sep 10, 2013 12:47 am

by rpowell

If you remove the cable then battery does the post go in? I'd also shine a flashlight and see if there is anything down the seat tube.

A long shot but you could have routed the di2 cable between the brake cable and frame (assuming mech caliper).

hernejj
Posts: 37
Joined: Tue Sep 17, 2019 6:27 pm

by hernejj

I'm having this same issue with my new 2020 SuperSix. Does anyone know why the cable ges pinched? Or more importantly, how to fix it? :)

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I'm not a di2 expert but it seems you have too much loose cable in there. Either thst or your seatpost is very long.

Try bundling the excess cable up so you have enough just to expose the bundle when you remove the seatpost. Either that or try to access the other end of the cable and pull it while inserting the seatpost.

Also what about filing away the chamfer on the end of that seatpost? The current one is pinching the cable.
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Dan Gerous
Posts: 2413
Joined: Sun Aug 12, 2007 6:28 pm

by Dan Gerous

On the Synapse, I found tilting the bike forward makes it easier to insert the seatpost, it helps the wedge stay forward and out of the way and the Di2 wire not pinching itself between the seatpost and the inside of the seat tube as the inside of the seat tube has a little bit more gap below the seat clamp zone. I suspect it might also help on the new Evo, both to make sure the wedge stays put but also so the wire doesn't get caught in the space where the seat stays start.

An idea could be to cut a bit of plastic out of a soda or water bottle and stick it behind the battery, sandwiched between it and the inside of the post, and leaving it long enough to extend below the end of the post to prevent the wire to get pinched.

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