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-   -   Are threadless stem risers safe for tandem? (http://www.bikeforums.net/tandem-cycling/507961-threadless-stem-risers-safe-tandem.html)

Monoborracho 02-03-09 11:14 AM

Are threadless stem risers safe for tandem?
 
I'm considering raising the captains handlebars on my Burley above what can be accomplished with a stem change. This means a stem riser such as Delta, Dimension, or Zoom. I realize it's only one more connection of the steering mechanism., i.e, stem -riser-steerer versus just stem-steerer.

Given the increased weights and dynamics of a tandem, does anyone have any thoughts about safety or is it anymore of a concern than it would be on a single bike?

Has anyone installed or used a stem riser on a tandem?

Thanks.

embankmentlb 02-03-09 02:19 PM

1 Attachment(s)
Have you considered a high rise stem like this one?

merlinextraligh 02-03-09 02:38 PM

What kind of steerer tube? How many cm of spacers are you running already? I would check out your proposed setup with the Fork manufacturer, and the manufacturer of the riser.

And I'd be very leary if the steerer is CF. (other than the Alpha Q tandem fork that is designed for a lot of risers.)

Monoborracho 02-03-09 03:19 PM

Quote:

Originally Posted by embankmentlb (Post 8298864)
Have you considered a high rise stem like this one?


What brand of stem is that? I have a Dimension adjustable on right now.

Merlin- Steerer is cromo.

cornucopia72 02-03-09 11:52 PM

Give Mark at precision tandems a call... if it is possible and safe... he will set you up.

embankmentlb 02-04-09 06:47 AM

Monoborracho, the stem is eleven81 brand. This particular one is 130 length.

Onegun 02-04-09 10:01 AM

Quote:

Originally Posted by Monoborracho (Post 8297709)
Given the increased weights and dynamics of a tandem, does anyone have any thoughts about safety or is it anymore of a concern than it would be on a single bike?

Has anyone installed or used a stem riser on a tandem?

Thanks.

Yes. They work fine. A stem riser is subject to its maximum stress from a strong rider pulling on the bars in a climb, and that's the same on a tandem as it is for a single. No more concern necessary than on a single.

dubbelop 02-04-09 12:42 PM

Quote:

Originally Posted by Onegun (Post 8303531)
Yes. They work fine. A stem riser is subject to its maximum stress from a strong rider pulling on the bars in a climb, and that's the same on a tandem as it is for a single. No more concern necessary than on a single.

Same here. We run a Satori (aka Zoom and other brands) on a Cannondale Road Tandem. It's absolutely as sturdy as a 'normal' stem would be.

http://www.xs4all.nl/~mmhoff/images/...rhoger_800.jpg

zonatandem 02-04-09 10:37 PM

Yes it's safe (if properly installed).

Monoborracho 02-05-09 09:43 PM

Thanks everyone. I was in the big city for a couple of days and I have picked up a Delta riser. When I get the Burley squared away I'll post a pic.

DaveloMA 04-14-10 12:42 PM

Have you done this mod yet? I need to do the same on my Burley Rumba, and I'm wondering about the need to run new cables.

Thanks!
David

zonatandem 04-14-10 05:17 PM

Depending on height inbcrease new cables ^may^ be necessary.

Monoborracho 04-14-10 07:11 PM

Old thread, a new day,

Yes, I put a stem riser on my Burley soon after we started pedaling TWOGETHER (as Zonatandem would say) and have had no problems at all. Just check and double check that everything is always tight. You may need to do the cables again. This was an 8-speed flat bar which I converted to 9 speed, drop bar w/ R600 short reach brifters. For us, as a starter bike, it has worked out great.

http://i292.photobucket.com/albums/m...g?t=1271293668

ThaiTandem 04-15-10 12:28 AM

Dimensions Steerer Extender is working for us on our Cannondale Street Tandem, but not without a bit of frustration. For some reason the fit is not that great on our steerer. We're also relying more on the lower bolt as the upper one will not clamp down as much. Have tried two different extenders from Dimensions and both have the same problem on this steerer. Have also tried clamping the extender at slightly different elevations (number of spacers) on the steerer, but with little effect. Stems clamped directly to this steerer work just fine, so suspect it's the riser(s) that is a bit too big for us.

However, torquing the bolts with a 12" crescent wrench on the allen key has held for nearly 1,000 miles so far--probably not to spec but holding up during some pretty rough riding on a regular basis. I check it regularly, as I'm a bit more concerned about it getting loose given that Cannondale now uses integrated headsets with this frame.

Monoborracho 04-15-10 06:34 AM

The extenders are cheap. I suggest trying another one.

You should be able to simply eyeball a spacer going up and down on the steerer tube to tell if something is out of gauge. Both bolts need to be clamping evenly on the steerer. If you had to overtorque, you never know where there is a fatigue crack waiting to bite you, particularly in the steering mechanism.

ThaiTandem 04-15-10 06:51 PM

Monoborracho, indeed remain concerned about the set-up. When I got the bike last December, I did measure the steerer with calipers and found that it was consistent up and down its length. Spacers and stems all seem to be fine. Ideally I would like to find a stem bar combo that would work with maybe a longer steerer (new fork), but in working the geometry and available stems on the market, there really are not many options. Moreover, pretty hard to sort out from here.

The lack of headtube height was the biggest surprises for me with this bike. Have never needed such a device before in decades of cycling and the bikes to go along with it. It was a long search (due to my size) that led me to this jumbo-sized Cannondale and Tandems East, and when I was actually told that I would need such an extender I was a bit surprised. But given the dealer, like others here, said they're often used, I just went with the flow as we were glad to finally have secured a bike before the end of my last stay in the US. Maybe I should try to locate a Zoom Heads-up or some other brand of extender and see if that offers better grip.

Indykid 04-15-10 07:59 PM

ThaiTandem, I have an '09 Cannondale StreetTandem. I have used a Delta stem raiser an it fit nice and tight. http://www.deltacycle.com/Stems-Alloy-Stem-Raiser

ThaiTandem 04-15-10 10:07 PM

Indykid, that's great to hear. Not assuming any trends, just sharing my experience. Could be that the two risers I got came from a batch that were a bit out of spec? Given the torque I was using, I did have an LBS check it out as well prior to my repacking it for the journey here. The mechanic agreed that something was amiss, but since it was holding after some hard riding/climbing, "should" be ok. Wish I had more time there to fully sort it out. Back together here and another 900 miles and it's still solid, just not ideal. So will continue to keep an eye on it while also looking for a different set-up. Anyhow, the bike's a great value and has otherwise been working out well for us.

Also, I think the Delta and Dimensions are the same risers with different names, so we may be using the same thing.

Onegun 04-16-10 06:11 AM

Quote:

Originally Posted by ThaiTandem (Post 10678340)
Also, I think the Delta and Dimensions are the same risers with different names, so we may be using the same thing.

That's a definite possibility, but I, too, use the Delta riser on our Fuji tandem with no such problem.

Also, be aware that Salsa makes a variety of 40 degree rise stems that might also get you more upright without the riser. It's the Moto Ace S.U.L. stem. I use it on a used fixie I bought, and would have no qualms about using it on the other tandem, but I already had the stem riser installed. You'll have to shop around to find one, (and do be aware that there's a recall on their Pro Moto stem).

ThaiTandem 04-16-10 07:27 AM

Onegun, I was indeed hoping I might be able to find a stem that would allow me to ditch the riser, but to get my desired geometry without the riser, would need about a 160mm stem at 45 degrees. The closest production stem I've seen is the Look adjustable that extends up to 150mm, and way pricy. I figured I could get a custom stem made for less if I wanted to go that rout, though the dealer advised me against it fearing that I may not be able to trust it? Assuming no problems before my next trip east, I will just bring the fork with me and get things sorted while I'm there. I just ran out time and options trying to get this done between receiving the bike, discovering the problem, waiting for a replacement riser to test, holidays, etc.

Onegun 04-16-10 07:52 AM

Quote:

Originally Posted by ThaiTandem (Post 10679378)
... would need about a 160mm stem at 45 degrees. The closest production stem I've seen is the Look adjustable that extends up to 150mm, and way pricy.

Just kidding, but ..... sounds like you need an adjustable stoker stem on the front! :innocent:

ThaiTandem 04-16-10 08:33 AM

Quote:

Originally Posted by Onegun (Post 10679492)
Just kidding, but ..... sounds like you need an adjustable stoker stem on the front! :innocent:

Yup, that jumbo frame did not turn out to be as "jumbo" as I needed, but it's working out ok and we're having a great time regardless. Will certainly feel better once this potentially precarious stem situation is resolved.

DCwom 04-19-10 06:13 AM

+1 on the Delta. After experimenting with an adjustable stem I realized I wanted the height but not the angle of a high rise stem so I ended up going back to my original stem with the Delta riser. I'm actually surprised by the number of folks who are using risers in this forum.

zzyzx_xyzzy 04-19-10 07:09 PM

try a google search for mod trials stems. They're not on most bike parts websites so you have to do some digging, but they come in some nutso sizes like 165mmx35d, 180mmx40d.

examples:

http://midwestbiketrials.com/store/i...products_id=10

http://cgi.ebay.co.uk/onza-black-all...e#ht_600wt_941

ThaiTandem 04-20-10 10:16 AM

zzyzx_xyzzy, thanks for the trails angel. I've poked around quite a bit trying to find something that might fit me, but can't seem get the right mix of angle and length. The Echos you found are some wild sizes, though a bit on the long side, and/or angle too shallow for my needs. I have found if I want to go with a new uncut fork I can get another 1.5" in elevation that would put the Echo 125mm x 28 right at the sweet spot. This challenge has made me yearn a bit for the greater flexibility of quill stems.


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