hi, is it worth it to buy an extralite ultrastar and tune top cap or something similar to reduce weight on the bike, I have a super six evo, already pretty light, but the fsa expander kit is pretty heavy, we can save about 40g with the ultrastar, but 42$ (ultrastar) + 20$ (tune cap) + shipping, maybe I can save elsewhere for less or for the same price. but elsewhere, not sure if we can save 40g for just 80$. i've already ti skewers... 45g

what do you think?

thanks

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Ninja

My black alloy top cap and bolt from torontocycles is pretty light, actually I think its the same weight as my tune cap and bolt.

The extralite is a great piece of stock but not sure where you can get it at a lower price or better shipping fees.

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2013 rocky mountain vertex 29er
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Top cap by MT zoom (check ebay) at about 4.5g incl bolt. Make your own gumgum using a urethane ring and 2 alu washers and a brake mount alu female nut.....$25 should see it all done.

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Used to race....got too wrinkly and old Updated: Racing again! Thought this was unlikely! Eventually, I may even have a decent race!

EVERY AREA YOU CAN SAVE WEIGHT IS ALWAYS WORTH IT.

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Exp001

I've been very happy with the combo you described. Found it on eBay for $50 and saved 40g over the cannondale expander

Hi ! Can you give me more details on which materials you bought on ebay to make your gumgum ? I am in the process of building up my Evo as well and am looking at alternatives to the SI compression plug. Thank you !

Bought a gum gum expander and one of the fairwheel top caps today. It totals $30 and weighs 15g for the set...much better than the 45g Neco and FSA I currently have to choose from.

If you're thinking about the gum gum might want to order quick...I just got an email that it came in stock today but it also might not sell out that fast either...haven't been looking long enough to know anything other than it was sold out last week when I wanted to buy it.

It's likely worth mentioning that the gum-gum gives carbon steerers NO support from being slightly crushed by the stem, and as the stem and the expander doesn't push against one another, it's a common problem that the stem starts creeping upwards, loosening the headset. Some mashed up rubber rng is doing nothing to hold the stem down, which a metal expander does.

Gum-gum works for some, but it is a well known problem and many have tried and given up on it. Do a search.

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Kinesis RaceLight T2

Mountainbike
Van Nicholas Zion Ti

The Tune Gum Gum is the minimalist version of an expander and takes a bit of work to get it right the first time but you do same some grams for little $$$$......a solid alloy expander does provide a bit more support on the steering tube but at 4-5 Nm on the stem bolts the Tune does provide some support. If you do experience some tappering of the fork with a Tune Gum-Gum, Extralite or Schmolke cap then I would question the fork quality. We have the Gum Gum on stock and have used it on various builds without any fork problems so far.

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www.royalbicycles.com

Ultrastar - 7 grams.
Parts of Passion top cap - .7 grams.
Schmolke Carbon bolt - .7 grams.

Total weight is under 9g for the WHOLE setup.

Not the best grams-per-dollar weight savings, because it cost about 80 bucks... but the UD carbon cap and bolt match my raw UD carbon stem really nice, and the Ultrastar works perfect.

haven't heard that before. Are you saying that the top cap ends up pulling the gum gum expander up instead of the gum gum pulling it down?

If that's the case, it sounds like problem would be improperly installing the gum gum to torque specs (not enough torque) or even just not enough friction inside the tube (hairspray trick or some carbon paste would fix that).

Regardless, I'll start looking into it as I'm interested to see what the problem is that others run into. I might also "jimmy-rig" an aluminum shim to use with the gum gum to try and better emulate a more traditional expander when it does come.

I think he is presenting two problems with the Gum Gum:

1. The Stem compressing the steerer tube
2. The gum Gum pulling out as it doesn't hold

The first problem is a first for me....never heard of a stem actually crushing/compresing the steerer tube when installed correctly. As I mentioned I would question the quality of any fork that has problems with 4-5 Nm applied on the steerer tube.....the rider weight puts much more force into a steerer tube than that.

The second problem is a bag of mix results.....on some forks the Gum Gum works from the start and on some you do have to play around....and on some cases it just doesn't work. It could be inside diameter of the fork and surface finish...besides incorrect setup.

Keep in mind that a top cap expander function is just to eliminate the front end play so minimal torque should be enough to make any expander work. Once you have setup your stem with the required torque you could actually take it out (not that I recommend that anyway)

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www.royalbicycles.com

No, I'm saying that the gum-gum does nothing to actually hold the headset together, it's about as useful as having no topcap at all. It's perfectly fine for preloading the headset. But after that, it really doesn't do much to keep the stem from creeping upwards on the steerer due to vibrations/bumps when riding.

I know alot of people don't even use topcap, and can't understand or refer to user error when other people can't get it to work and the stem slips upwards, loosening headset preload. It is a much discussed topic, where alot of people aren't having any problems - but then alot of people are, even with everything setup perfectly, using friction paste in stem/steerer interface and whatnot.

Really, this is not a matter of poor setup, but a mechanical issue. Carbon steerers are fairly soft (compared to aluminum ones) and they have a lot of give, that's not a matter of poor quality forks, and with a metal expander there is actually something pushing against the stem just like the stem is pushing against the expander, they somewhat hold each other in place, if you will.

Even here on WW there are lots of threads about people who have binned the gum-gum in favour of the ultrastar, just because of this.


P.S
Oh, and I don't mean actually CRUSHING the steerer so it breaks, but a stem will compress a carbon steerer (ever so slightly) as the material does have some give. Try installing a metal expander, and then the stem. Now remove the expander, the stem bolts will be sligtly looser as the expander expanded the steerer. The stem does the same thing in the other direction. I'm not talking monsterous tourqe on the bolts here either.

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Roadbike
Kinesis RaceLight T2

Mountainbike
Van Nicholas Zion Ti

I've never tried a GumGum but have two Ultrastar 2's on two bikes. It works very well. My top cap is a Carbon with bolt that weighs 5 grams. Its been on my Roadbike for over 5 years but the fork, an Alpha Q GS30, has a proprietary starnut in it.

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