# Help save my Synapse from eBay



## bigreen505 (Jun 10, 2007)

Ok guys, final attempt here, please help me save my Synapse from the sale block. I don't race, just ride Colorado mountain roads for enjoyment.

I have a 2006 carbon Synapse in a 56 and I just can't get used to the handling of it, particularly on fast downhills. The steering is twitchy at speed, but the bike doesn't seem to want to turn. In high speed turns, it feels like it wants to understeer me right off the road. It also doesn't want to lean into a corner, but I feel like I have to lean it over and really push down on the inside handlebar more than I'm used to on other bikes to make it turn. Wheels are Ksyrium SL3. There is a possibility that the frame is just too big for me. It currently is set up with a 90 mm stem and just over 8 cm of saddle-to-bar drop. I kind of feel like I need a bike with a shorter reach and taller stack height, but I'm not really sure. I can raise the stem a few cm.

My previous bike was a Wilier which had a very tall head tube and very short chain stays, but handled and was rock solid at any speed I saw.

For those not familiar with the bike, it is similar to the current Synapse, but the geometry is a little more "standard" with a shorter head tube and longer top tube, possibly also shorter wheelbase. My 56 has a 16 cm head tube, 56 cm tube, and 73* head and seat angles.

Any thoughts are appreciated.


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## georgewerr (Mar 4, 2009)

Have you returned it to your LBS to have them go over it, maybe its defected in some way. 

I have never rode one except for a very short slow ride with a buddy who bought one and we switched bikes for a mile or two. I did not like the geometry of the bike as I'm use to a CAAD 9.


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## bigreen505 (Jun 10, 2007)

Thanks George, there's nothing wrong with my frame that I can tell. On the contrary, it is exceptionally well aligned. That said, I have never ridden another Synapse to compare. While the Synapse geometry is not too far removed from other bikes I have ridden, it is pretty different from my last bike.


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## CHL (Jun 24, 2005)

This is what some may have called "speed wobble." If you google the affliction, you'll see a very well detailed explanation of the phenomenon by Jobst Brandt. Frankly, I don't understand the physics behind it but it's about the bike's frame reaching natural resonance. Calfee also has an article regarding fork symmetry that can contribute to the issue as well.

My 2011 Super Six HM had the same issue. Tried changing wheels and fork. The new forked helped a lot but the issue remained. It's rock steady now on my replacement frame. I Just don't know what about the old frame caused this.

chl


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## bigreen505 (Jun 10, 2007)

Thanks CHL, I've had speed wobble and this definitely isn't that. Honestly the twitchiness isn't what bothers me, it is the extreme understeer and reluctance to lean over.


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## Brazos (Jun 20, 2009)

I have a 2009 Synapse (alloy). My bike came with RS-10 wheels and Maxxis Fuse tires. When I would go down steep hills and get up to around or above the 30 mph mark my bike no longer felt stable. Ridable but just slightly unstable. Then last summer I bought the Ultegra 6700 wheelset and Hutchinson Atom Tubeless tires. Night and day difference. The bike is now rock solid going downhills at speed. In your case you have a 2006 carbon frame (I think they have since changed the geometry) and different wheels. If by chance you have a different set of wheels or can borrow some off a friend it would be a cheap, quick experiment. Even though you have some good wheels there could be something wrong with them or the tires.


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## bigreen505 (Jun 10, 2007)

Thanks Brazos, it's not the tires as I have been through a few sets, but the wheels are definitely worth looking into. I don't think there is anything wrong with them, but I'm not a fan of their aerodynamics which could be affecting handling.

How do you like the tubeless tires?


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## Brazos (Jun 20, 2009)

Swapping out wheels is worth a try since it is quick and won't cost anything. I love the tubeless set up. I have no plans to go back to a tubed tire and wheel set up. Tubeless is just too easy w/ a nice ride quality.


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## nhguapo (Oct 20, 2010)

I ride a Super Six and experienced some of the twitchiness you described on fast descents. I can't say I've had to struggle through any understeer. I had my wheels checked and it turned out the front hub was loose. I got it tightened up and haven't had any other issues with handling.


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## bigreen505 (Jun 10, 2007)

I guess I should clarify, it is not the twitchiness that I object to, it is the understeer and generally ponderous handling at speed. I mentioned the twitchiness in case they were related, like perhaps my position on the bike doesn't have enough weight on the front wheel.


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## Bob Ross (Apr 18, 2006)

I have a 2006 Synapse Carbon 2 in a 58cm (I'm 6' tall, ~33" inseam, running maybe 3cm saddle-to-bar drop w/ a 100mm or maybe 110mm stem) and I find it has no trouble on steep curvy descents. It torches long mountin descents with an incredibly comforting sense of stability & responsiveness.

However, I do think I understand what you mean when you say "the bike doesn't seem to want to turn". There's something about my Synapse that makes it extremely stable, as if it _wants_ to go straight. I've never noticed this when trying to dive into a turn, but I do notice it if I try to negotiate a series of quick, small, back&forth turns (e.g., avoiding a series of potholes at the last minute). It's less responsive than a more nimble bike in that sense.

But for fast downhills mine's been rock solid, the complete antithesis of "twitchy".


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## WMBigs (Aug 29, 2009)

2010 Alloy Synapse with the RS10 wheels and stock Vittoria tires. This bike seems to be twitchy or quick at normal riding speeds. But on a smoking down hill it is rock solid. I think the twitchy is the result of the massive headtube juncture and the stability is from the laid back head tube angle. My old steel Bianchi feels less twitchy on the flats and less stable on the downhills. The Synapse has an incredible stiff feeling at the bottom bracket- feels like it does not give, just accelerates with each pedal stroke.


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