mburchard

Got a new stoker barstem from Calfee a week or two ago. Looks great, but interesting that heavier than old adjustable stem (Bob Davis) and bars, 439 vs 411 gm. Viper Wing is supposed to be 210gm, so that makes the stem of the barstem almost 230gm.

Dean V

More Bling though.

mburchard

Yes, more bling :-)

Bad1

Not to bad of a weight for a stroker stem considering da Vinci Designs TI stem is 188g

DubT

Your weights are interesting. Here are some weights that I recorded a few months ago.

your alloy bars must be extremely light!

Here are the numbers. Alloy bullhorn stoker bars: 410 grams, Carbon Fiber Profile bullhorn bars: 216 grams. Ritchey 120mm 30 degree stem 160 grams, new Trial Tech stem 35 degree X 180 long 243 grams.


Total weight of the original = 570 grams, Total weight of the new = 459 for a reduction of 111 grams.


I checked the weight of an adjustable stem and it weighs 370 grams, so I opted for the lighter Trial Tech stem.

mburchard

They are not alloy. Chopped and inverted Kestrel EMS in a 46cm.

fietsbob

at least the CF was used to make a broad surface for the stokers hands to rest on , now there needs be some comfortable padding added to that..

twocicle

For comparison, we have the Cobra Wing @ 228gm (including cork tape wrap) + 3T ARX II Team stem[/URL] @ 15cm/17degrees weighing 160gm = 388gm total weight, $315 total cost including tape. The Team stem came with a red stripe which I did a hack job painting out using some touchup I had on hand. The stem is attached to seatpost using a black Cane Creek shim.



Prefer the looks of yours though.

Bezalel

How well does that shim hold? I often ride with inexperienced stokes and am concerned that they may try to twist their handlebars.

twocicle

Many people here on this forum use a shim. My impression is that it is easier on the seatpost (prevents gouging) than directly attaching a stem of the same diameter. The slight texture on Thomson posts also helps the shim to grip, but you could use some grip compound on most posts and shims if necessary.

Chris_W

We use a shim between our trials stoker stem and the captain's seatpost. The shim certainly doesn't cause a problem because it is the seatpost clamp that is the weakest point in the setup - if the stoker turns the bars (or if I do so when manhandling the bike when stationary) then the whole seatpost, saddle, and bars move together. I'm thinking of putting a double-bolt seatpost clamp on to prevent this from happening so easily.

vrooom3440

Careful here... just as parts might slip and move too easily it is also possible for parts to not slip and move too hard. Then instead of a benign slip you get a more severe break. Think of that seat post clamp as a fuse to handle overloads and keep you from smoking the entire circuit.

waynesulak

+1 especially with carbon bars

zonatandem

We have the original c/f adjustable stoker stem that Bob Davis developed back in 2003.
40,000 miles later, it still works great.
We do have a ti 'glue-on' on it to hang our mini-garage door opener and put on a QR instead of a bolt so we can easily adjust the length of the adjustable stem when another stoker wants a ride. Have had to adjust it only a couple a times a couple millimeters at stoker's request.
We also utilize the c/f stoker hand rests that Bob made for us when he built the bike.
Pedal on TWOgether!
Rudy and Kay/zonatandem

mburchard

Which shim? I guess Calfee left it to me to sort out fastening a 1 1/8 stem clamp to a 27.2 seat post. Not very nice, particularly since I sent them the old one to copy, and the new one was not exactly a sale item. If a shim was/is required I would think they could have sent it to me ...

mstyer

1 1/8" = 28.6mm, 28.6 - 27.2 = 1.4mm

Bikeman Problem Solvers 1.4mm Shim, 27.2 Seatpost to 28.6

twocicle

Cane Creek Shim-27.2 I.D./28.6 O.D.
https://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

mburchard

Got it, tks. Calfee is sending me one, so maybe they will have already cut to size ...