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Does anyone have any experience with the Giant conduct system (semi hydraulic breaks) and compatible stems?

My partner bought a bike which came with a conduct 100mm stem. She feels that the reach is too long for her purpose (long distance road/gravel touring). When holding an other stem next to it I can see that the bolt spacing is off just by a few milimeters.

Is the stem proprietary or is this a metric to imperial measurement difference?

Any advice is appreciated I'd also consider a 80mm MTB stem if the bolt pattern is the same, but I can not find any dimensional drawings for stems on the Giant website.

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  • How costly would it be to ask a machinist to make a "copy" of the faceplate of your preferred stem but adding some "extra meat" with threaded holes just to hold the Conduct device? Otherwise, Once you have a Stem that suits you, simply attach the device in any "elegant enough" manner, as your handlebar no longer depends on it.
    – Jahaziel
    Sep 7 '20 at 21:16
  • We went to our local Giant store yesterday. The "damage" was 28€ for a shorter stem. I think all other options would have been more expensive
    – Martin H
    Sep 8 '20 at 5:58
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Giant's page on the Conduct semi-hydraulic brake system says that, emphasis mine:

There's no need to replace your mechanical brake lever or handlebar tape - simply shorten your current cable housing, then mount the new master cylinder on your Giant Contact SL or Contact stem.

It appears that the lowest-end Contact stem is $53 in the US. This is more expensive than other low-end stems. However, if this stem fits (as Giant's page indicates it should), then it's going to be less expensive than buying and installing hydraulic shifters and brakes (or, alternatively, getting a good cable-actuated brake, probably a cable-actuated hydraulic one like the TRP Hy-Rd, plus good compressionless housing).

Stems in general do not have interchangeable face plates, i.e. there's no industry standard for the spacing between bolts. In most cases, riders won't need to interchange face plates.

I agree with juhist that we almost never want to interfere with a rider's freedom to choose their stem. Newer riders need some time to figure out their desired stem length. Even established riders may see their needs change over time and they may need to change stem length and orientation. Fortunately, the solution in this case does not appear to be terribly onerous.

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  • For once I thought something is standardized. They could have, at least, designed the cover plate with long holes to allow for different spacings. I guess a Giant stem will be the cheapest, yet not cheap, way to get the bike fit right
    – Martin H
    Sep 6 '20 at 17:44
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Giant sell the Conduct system as an aftermarket 'upgrade kit', and one of the requirements says,

If you are fitting to a non-Giant / non-Liv branded bike you will need a compatible stem with the correct 31.8mm face plate & bolt pattern - such as the Giant Contact

I would think that stems are available from other manufacturers which happen to suit this face plate and bolt pattern but more likely to require some trial and error.

So on that basis you could start with a Giant Contact branded 80 mm stem with 31.8 mm face plate and expect it to work, or at least have some recourse with Giant if not. These shouldn't be difficult to find, but there are a lot of variants, so check the specs you have vs what is available.

Giant have stems for sale on their site and you could no doubt contact them in advance anyway.

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So it seems that Giant conduct system uses a device as the faceplate of the stem to convert mechanical cable motion to hydraulic fluid motion.

This is a very poor design. There is no standard for stem faceplates. If you buy a replacement stem, you can be 99% certain its faceplate is different.

The easiest way forward is to get rid of the mechanical levers and the mechanical to hydraulic conversion unit. Prefer an all-hydraulic system.

I do not find anything interfering with my freedom to choose stems desirable.

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