Spacers above stem cannondale

Discussion in 'Cycling Equipment' started by Uawadall, Jul 22, 2016.

  1. Uawadall

    Uawadall Well-Known Member

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    Hello, I wanted a lower/more aggressive position on my Cannondale synapse. I flipped the stem and put the 4 mm of spacers above it. Ive been using it like this for 3 months or so and it suits me well. It gave me at least a 1mph boost in speed and the lower position hasn't caused any back problems.

    I've been researching stems and thinking of getting a stem lower and longer. Upon researching the subject, it seems Cannondale strictly prohibits spacers above the stem for safety reasons. Have you heard of anyone having problems caused by spacers above a stem with cannondale?

    I'm going to take it to a shop tomorrow and have them trim it. Could care less about resale value,changing position later, or anything like that, just want to be safe and comfortable.
     


  2. CAMPYBOB

    CAMPYBOB Well-Known Member

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    Most bike manufacturers require at least a 5 MM spacer above the stem. I never heard of one that frowns upon a spacer above the stem, but anything is possible. I mean...yeah...a 30 MM stack up top is not only fugly, but it's a great place smack The Boyz on in a fall.

    I would guess that with a carbon steerer that manufacturers prefer to have a full length of tube running through the stem and then some in order to minimize the possibility of the stem not having enough contact length and 'working' on the carbon with micro-movement and/or flexing that might cause a stress riser, cracking of the steerer or some other type of catastrophic failure.

    Aside from being in a crash and slamming into the compressor plug top cap or a spacer stack...well...that is usually the least of my concerns in a crash. At the same time, the Family Jewels taking a hard hit on the stack might have you singing in the Vienna Boys' Choir for a few days. Always a considerastion dating back to the days of the 5-speed top bar Stik Shift found on the Schwinn Fastback's...Google it.

    I've seen lots of pro bikes running full slammed stems with no spacers and I've seen them slammed with a thin spacer up top. With a very carefully measured and cut steerer it is probably dealer's choice.

    Now...for the disclaimer:
    It is the policy at the famous CampyBob School of Bicycle Set Up and Style Studio to run a 5 MM or 10 MM spacer above the stem. I instruct all my many loyal disciples and monks to do so in order to get the full clamping length and keep potential stress on the steerer to a minimum. Besides...Where else are you going to put that ultra chic contrasting frame color anodized and engraved Hope Racing spacer and set off that awesome custom top cap you just bought on eBay? Huh? A man's got have some place to put a little bling!
     
  3. Uawadall

    Uawadall Well-Known Member

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    Was tired while typing...It has 4 5mm spacers on top. It looks a little fugly with 20mm above the stem. I'll go to the shop and see what they can do. Keeping 1 sounds reasonable, maybe if I buy a new stem from them they'll give it a clean cut for free.
     
  4. Bob Ross

    Bob Ross New Member

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    Cannondale has long been very explicit about this seemingly-odd caveat ("No spacers above the stem!"), but their reasoning is simple: Cannondale's starnut works differently than the much more common type used by other threadless headset manufacturers (e.g., Chris King NoThreadSet). I'm not super familiar with how those differences manifest themselves, but I think it has something to do with being a much shallower starnut than typical, so there's nothing inside the steerer to resist crushing by the stem in this new lower position.

    In any case, they're pretty serious about adhering to that policy: Not sure how old your Synapse is, but if it was still under warranty it's not anymore, you've violated Cannondale's warranty by moving a spacer above the stem.
     
  5. CAMPYBOB

    CAMPYBOB Well-Known Member

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    Thanks, Bob. I pulled up a sample owner's manual for the Synapse line to see what was being advised.

    Cannondale's Synapse carbon steerer owner's manual. It uses a compressor plug (not star nut, like aluminum steerers sometimes use) that looks just like every other compressor plug I've worked on.

    The instructions are...weird. They want the expanding element of the compressor plug approximately aligned with the lower stem clamp bolt. Balancing the compression force of the stem on the carbon steerer tube with the expanding force applied by the compressor plug's expansion wedge ring.

    In theory...a good thing. In reality neither force generated by proper fastener torque should be enough to threaten damage to the steerer tube.

    http://cf-prd.cannondale.com/~/media/Files/PDF/Dorel/Cannondale/Common/Support/ROAD OWNER MANUALS/SYNAPSE CARBON (2015)/129387_OMS_Synapsecarbon_en_low.ashx?vs=1&d=20150813T105345Z

    With a 2 to 3 MM gap from the top of the steerer to the underside of the compressor plug top cap, all a fellow would have to do to keep things in alignment with a 5 MM spacer above the stem is to use 5 MM of washers between the compressor top cap and the expanding wedge ring. Going to a 10 MM spacer might require getting a 10 MM longer bolt in addition to the 10 MM washer stack in between the compressor cap and expander wedge ring.

    All of this does violate Cannondale warranty, of course. And you may also contract a mosquito-born virus while performing the modifications. And you could contract hoof & mouth disease while searching your spare nutz & bolts bin for the proper thickness and diameter washers necessary.

    Don't know if the OP has an aluminum steerer Synapse or a carbon steerer Synapse or what style star nut or compressor plug his bike has, but man...if I would have known working on dainty and fragile bikes would have become this retarded 46 years ago, I would have taken up sky diving.
     
    #5 CAMPYBOB, Jul 29, 2016
    Last edited: Jul 29, 2016
    Bob Ross likes this.
  6. Uawadall

    Uawadall Well-Known Member

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    It wouldn't be a big deal as I bought the bike for 800 used and already got more than a good year out of it. Not to mention its a sturdy aluminum bike, but how would they know that spacers were above the stem unless you told them yourself? Not like they're going to send an investigator.

    had the thing cut this week leaving room for 1 5mm spacer. The bikes looking clean!
     
  7. CAMPYBOB

    CAMPYBOB Well-Known Member

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    TREK went through some bullshit about not using Brand X or Brand Y stems because their aluminum and carbon steerers were snapping like pretzels. That was right around the time George Hincapie went through a sector of cobbles during P-R with the handlebars no longer attached to the bike.

    Cannondale specifications allow 55 MM worth of stack from the top of the head tube to the bottom of the stem. 2+ inches of steerer sticking up has always been more questionable in my mind than a 5 or 10 MM spacer above a stem or no spacer below a stem or whatever weird thing a manufacturers kiddie engineers and their 3-D modeling and finite element analysis software came up with that got translated kinda sorta into the cheapo owner's manual by some tech writer fresh out of law school.

    Tighten things with extreme care and always always always keep that bike clean and well inspected for cracks and such. Hopefully, we'll all live to tell lies about our racing on the porch of the old folks' home.
     
  8. Uawadall

    Uawadall Well-Known Member

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    Thanks for the reply's Bob and Bob! Very useful info, my next bike purchase definetly be a race style frame.
     
  9. Bob Ross

    Bob Ross New Member

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    In the event of a warranty claim they often do send an investigator (usually the local manufacturer's representative). And in the rare event that, say, your steerer tube snaps while riding and you get injured and you try to sue Cannondale for selling you a defective or unsafe product, they absolutely will send an investigator who will determine that you violated an explicitly stated safety policy and were in violation of the product's recommended usage. It's all company lawyers covering their collective asses in the overly-litigious society we live in imho.
     
  10. Uawadall

    Uawadall Well-Known Member

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    You're right in the event of something big happening. I guess one thing about getting a used bike is not gaining a proper respect for the owners manual. I've downloaded after this question, but thats more than a year of not thinking much about it. Regardless, my LBS trimmed it and it is fine structurally. Thanks for your input, i'll look at the manual up and down when I purchase my next bike.
     
  11. CAMPYBOB

    CAMPYBOB Well-Known Member

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  12. Uawadall

    Uawadall Well-Known Member

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    Looks like a spacer to me. Even the third generation shop owner who knows his stuff recommended I leave 1 spacer above the stem (which I did). His shop sells cannondales as well.
     
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