Seat stem mounted rack for Carbon seat stem?
#1
Fran & Nanette
Thread Starter
Join Date: Jan 2009
Location: Ridin' 'round the corner in Winslow, AZ
Posts: 231
Bikes: Gary Fisher Wingra, 30 yr old KHS Mountain Bike, Used Yakima traile
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Seat stem mounted rack for Carbon seat stem?
Can the seat stem type rack be safely mounted on a CF stem? We really like our Roubaix and Ruby, but it would be nice to be able to take a trip to the library with them without wearing a backpack. OTOH, if it isn't recommended, we'll continue to wear the occasional backpack.
#2
Senior Member
Join Date: Sep 2005
Location: In the foothills of Los Angeles County
Posts: 25,274
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 8273 Post(s)
Liked 9,028 Times
in
4,469 Posts
I did a 5 day trip where there were riders with seat post mounted racks on carbon posts. They did wrap the post with an old tube to prevent scratches and they didn't carry a lot of weight.
Another guy had a ton of weight in his, but he had an alloy post.
All of the women in this pic have carbon posts with racks.
Another guy had a ton of weight in his, but he had an alloy post.
All of the women in this pic have carbon posts with racks.
Last edited by big john; 08-20-09 at 04:37 PM.
#3
Member
Join Date: Aug 2009
Location: MA/ RI Coast
Posts: 36
Bikes: Giant TCX, Schwinn Sierra, Diamondback Outlook
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I've used and loved a post style rack on all of my/my son's previous steel/alloy posted bikes. I don't load them down more than 5-8 # or so but find their utility impossible to live without. For me it's a place to carry snacks/ lunch, wallet, windbreaker, fishing rod. ..... Makes a nice rear fender when riding in wet conditions too. I don't mind adding the 20 oz or so for that kind of utility.
FWIW, I just ordered one of these ( yesterday)for my new carbon posted Giant TCX.
https://www.nashbar.com/bikes//Produc...2_216833_-1___
I don't expect any issues as long as I protect the carbon with tape/tube material . Of course, I don't plan on carrying anywhere near the 25# capacity either.
I'll let you know more when it comes in.
p.s. The only downside I've found to these is that if you have one and your riding partner doesn't , you end up carrying all the gear! :-)
FWIW, I just ordered one of these ( yesterday)for my new carbon posted Giant TCX.
https://www.nashbar.com/bikes//Produc...2_216833_-1___
I don't expect any issues as long as I protect the carbon with tape/tube material . Of course, I don't plan on carrying anywhere near the 25# capacity either.
I'll let you know more when it comes in.
p.s. The only downside I've found to these is that if you have one and your riding partner doesn't , you end up carrying all the gear! :-)
#4
Time for a change.
Join Date: Jan 2004
Location: 6 miles inland from the coast of Sussex, in the South East of England
Posts: 19,913
Bikes: Dale MT2000. Bianchi FS920 Kona Explosif. Giant TCR C. Boreas Ignis. Pinarello Fp Uno.
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 5 Times
in
4 Posts
Carbon seat post and bolting anything onto requires a bit of care- so DON'T overtighten. Check the thickness of the post aswell- if it feels thin then don't do it. And to take as much strain off the post as possible- mount the rack as low down as possible on the post
Personally- I would rather buy a cheap ally post and not take the chance,
Personally- I would rather buy a cheap ally post and not take the chance,
__________________
How long was I in the army? Five foot seven.
Spike Milligan
How long was I in the army? Five foot seven.
Spike Milligan
#5
Member
Join Date: Feb 2008
Location: Lake Champlain/Adirondacks
Posts: 28
Bikes: Madone 4.6,Salsa Casserole
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
The lbs that sold me my Madone said not to and ,untill reading this thread, I believed them. But, I sure did miss it for all of the reasons stated. A few weeks ago, I purchased one of those triangular shaped bags ( I think it was through Nashbar, might have been Performance) that wound up fitting backwards and mounts to the top stem and the rear stem (below the seatpost). I really like it, it holds a fair amount, not quite as much as a rack mounted bag, but still can hold snacks, jacket, loaf of bread etc. I can even unzipp it while riding for a towel or snack or for an extra water bottle as it does make it so that only one bottle holder will work on the bike. Doesn't bother me while pedaling, has nice side illumination stripes, and seems to be aero.
#6
just keep riding
Join Date: Feb 2005
Location: Milledgeville, Georgia
Posts: 13,560
Bikes: 2018 Black Mountain Cycles MCD,2017 Advocate Cycles Seldom Seen Drop Bar, 2017 Niner Jet 9 Alloy, 2015 Zukas custom road, 2003 KHS Milano Tandem, 1986 Nishiki Cadence rigid MTB, 1980ish Fuji S-12S
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 173 Post(s)
Liked 33 Times
in
22 Posts
#7
Senior Member
+1
There's a reason they don't make carbon touring bikes.
If you put a lateral force on your carbon fiber seat post I'm reasonably certain you're exceeding the manufacturer's recommended performance guide. And while there is, no doubt, a safety factor built into it the seat post, I don't even like to contemplate what broken carbon fiber would feel like below the waist.
__________________
#8
Fran & Nanette
Thread Starter
Join Date: Jan 2009
Location: Ridin' 'round the corner in Winslow, AZ
Posts: 231
Bikes: Gary Fisher Wingra, 30 yr old KHS Mountain Bike, Used Yakima traile
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I think I'm beginning to see the light I'll wear a backpack when I want to run errands on the road bike. That way I won't be waddling around in bike shoes too much either.
I can always fall back on the Stumpjumper, which has a rack already in place. For that matter, we still haven't gotten rid of the Giant FCR. Maybe I'll just hang onto it for around town trips.
I seem to have read something about N+1
I can always fall back on the Stumpjumper, which has a rack already in place. For that matter, we still haven't gotten rid of the Giant FCR. Maybe I'll just hang onto it for around town trips.
I seem to have read something about N+1
#9
Senior Member
Join Date: Sep 2005
Location: In the foothills of Los Angeles County
Posts: 25,274
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 8273 Post(s)
Liked 9,028 Times
in
4,469 Posts
[QUOTE=Monoborracho;9534003]+1
There's a reason they don't make carbon touring bikes.[QUOTE]
Yes, and the reason is cost versus return. There would be no reason to try to save weight by building a CF touring frame, although I'm sure it could be built as strong as needed.
There are carbon 6 inch travel mountain bikes, carbon long-travel forks, etc.
I know that it's probably not the best idea to use a rack on a CF post, but my friends that have done it have had no problems.
I have never used a cf post, but I have broken 4 alloy posts. I have never tried a post mounted rack as I have a touring bike.
There's a reason they don't make carbon touring bikes.[QUOTE]
Yes, and the reason is cost versus return. There would be no reason to try to save weight by building a CF touring frame, although I'm sure it could be built as strong as needed.
There are carbon 6 inch travel mountain bikes, carbon long-travel forks, etc.
I know that it's probably not the best idea to use a rack on a CF post, but my friends that have done it have had no problems.
I have never used a cf post, but I have broken 4 alloy posts. I have never tried a post mounted rack as I have a touring bike.
#10
Member
Join Date: Aug 2009
Location: MA/ RI Coast
Posts: 36
Bikes: Giant TCX, Schwinn Sierra, Diamondback Outlook
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Well mine is here and installed. The post hast rack has 4 bolts on the clamp so I felt pretty good about tightening it uniformy on my carbon seat post. ( With a double layer of electrical tape under it for cut protection.) It's holding firm with only moderate tightening. I'll be surprised if there are any problems. My CF seatpost is decently thick and CF is strong stuff if you don't point load it. ( They build missle capsules out of it !)
FWIW: The rack as delivered weighed 590gr. The bag attaching hardware another 130gr. The (removable) bag was another 600gr (and 12"x7.5"x7.5"). Not exactly feather weight but versitile and worthwhile for my needs.
I can post pics if desired.
p.s. Nice rack too, BTW.
FWIW: The rack as delivered weighed 590gr. The bag attaching hardware another 130gr. The (removable) bag was another 600gr (and 12"x7.5"x7.5"). Not exactly feather weight but versitile and worthwhile for my needs.
I can post pics if desired.
p.s. Nice rack too, BTW.
Last edited by WeeHooker; 08-25-09 at 03:23 PM.
#11
Senior Member
Carbon seat post and bolting anything onto requires a bit of care- so DON'T overtighten. Check the thickness of the post aswell- if it feels thin then don't do it. And to take as much strain off the post as possible- mount the rack as low down as possible on the post
Personally- I would rather buy a cheap ally post and not take the chance,
Personally- I would rather buy a cheap ally post and not take the chance,
#12
Fran & Nanette
Thread Starter
Join Date: Jan 2009
Location: Ridin' 'round the corner in Winslow, AZ
Posts: 231
Bikes: Gary Fisher Wingra, 30 yr old KHS Mountain Bike, Used Yakima traile
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Well mine is here and installed. The post hast rack has 4 bolts on the clamp so I felt pretty good about tightening it uniformy on my carbon seat post. ( With a double layer of electrical tape under it for cut protection.) It's holding firm with only moderate tightening. I'll be surprised if there are any problems. My CF seatpost is decently thick and CF is strong stuff if you don't point load it. ( They build missle capsules out of it !)
FWIW: The rack as delivered weighed 590gr. The bag attaching hardware another 130gr. The (removable) bag was another 600gr (and 12"x7.5"x7.5"). Not exactly feather weight but versitile and worthwhile for my needs.
I can post pics if desired.
p.s. Nice rack too, BTW.
FWIW: The rack as delivered weighed 590gr. The bag attaching hardware another 130gr. The (removable) bag was another 600gr (and 12"x7.5"x7.5"). Not exactly feather weight but versitile and worthwhile for my needs.
I can post pics if desired.
p.s. Nice rack too, BTW.
I'd like to see a pic or 2 of the rack - the bike too...
#13
Senior Member
Join Date: Oct 2007
Location: SW Florida The Everglades
Posts: 207
Bikes: Rivendell Chevoit and a Panasonic 1986 7500 MTB
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
+1
There's a reason they don't make carbon touring bikes.
If you put a lateral force on your carbon fiber seat post I'm reasonably certain you're exceeding the manufacturer's recommended performance guide. And while there is, no doubt, a safety factor built into it the seat post, I don't even like to contemplate what broken carbon fiber would feel like below the waist.
There's a reason they don't make carbon touring bikes.
If you put a lateral force on your carbon fiber seat post I'm reasonably certain you're exceeding the manufacturer's recommended performance guide. And while there is, no doubt, a safety factor built into it the seat post, I don't even like to contemplate what broken carbon fiber would feel like below the waist.
#14
don't try this at home.
Join Date: Jan 2006
Location: N. KY
Posts: 5,936
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 973 Post(s)
Liked 511 Times
in
351 Posts
There could be a lateral force of 200 lbs at the collar on the bottom of the seatpost if you hit a bump in the road. I don't see how a 10 lb loaded rack would cause a problem.
I would sand down any sharp edges or corners on the clamp first.
Wrapping the post, and tightening just enough so the rack doesn't slip, would be good ideas.
I would sand down any sharp edges or corners on the clamp first.
Wrapping the post, and tightening just enough so the rack doesn't slip, would be good ideas.
Last edited by rm -rf; 08-26-09 at 12:40 PM.
#15
Senior Member
Join Date: Jun 2008
Location: Far, Far Northern California
Posts: 2,873
Bikes: 1997 Specialized M2Pro
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
It's eight miles to the grocery store, and I've done some runs with a backpack. It really isn't that bad. I guess the disadvantages are hot, uncomfortable, and higher center of gravity -- right?
#16
Senior Member
Join Date: Dec 2005
Location: Boulder, Colorado
Posts: 1,383
Bikes: Cinelli Supercoursa 69, Ritchey Breakaway Cross, Mondonico Diamond Extra 05, Coors Light Greg Lemond (built by Scapin) 88, Scapin MTB, Stumpjumper 83, Specialized Stumpjumper M4, Lemond Poprad 2001
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked 2 Times
in
1 Post
I am with the guy who said buy a cheap alloy seatpost for the rides with a seatpost attached rack. I am an engineer and if you look at the clamping needed to prevent the seatpost from moving from side to side it will eventually break a carbon post. The other thing is that there are a variety of carbon posts and this just makes the crotch roulette time variable but certain.
I ride with a rack mounted to the seat post which I can move from my road to MTB and to Cross bikes. I use a carbon seat post on my road bike and it is a simple task to switch it out. Not worth the risk...unless you are contemplating a vasectomy then you might just save some money. Gee I forgot this is the over 50 group. DON'T DO IT.
I ride with a rack mounted to the seat post which I can move from my road to MTB and to Cross bikes. I use a carbon seat post on my road bike and it is a simple task to switch it out. Not worth the risk...unless you are contemplating a vasectomy then you might just save some money. Gee I forgot this is the over 50 group. DON'T DO IT.
Last edited by Deanster04; 08-26-09 at 10:43 PM.
#17
Member
Join Date: Aug 2009
Location: MA/ RI Coast
Posts: 36
Bikes: Giant TCX, Schwinn Sierra, Diamondback Outlook
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
mcoz, here you go.
the straps and platforms holding them bolt onto the basic rack and are not used/installed unless you opt for teh bag as well.
Deanster04, I'm also a mechanical engineer with 24 years in the business and significant experience in composit use. Your statementabout certain failure is misleading and unqualified. If the seat post is built well (i.e not to thin walled) and installed with a rubber/taped sleeve and uniform tightness, I see no reason to worry about post failure as long as the rack is installed with consideration and used responsably. Agreed a carbon tube is weakest in a tortional state but the trick is to assure you don't grip it like a vise. As mine is set up, the lower lip rests on the frame to reduce any bending action in the Y axis and it will give and slip over the tape if torqued strongly in the z axis.
That said, to each their own.
the straps and platforms holding them bolt onto the basic rack and are not used/installed unless you opt for teh bag as well.
Deanster04, I'm also a mechanical engineer with 24 years in the business and significant experience in composit use. Your statementabout certain failure is misleading and unqualified. If the seat post is built well (i.e not to thin walled) and installed with a rubber/taped sleeve and uniform tightness, I see no reason to worry about post failure as long as the rack is installed with consideration and used responsably. Agreed a carbon tube is weakest in a tortional state but the trick is to assure you don't grip it like a vise. As mine is set up, the lower lip rests on the frame to reduce any bending action in the Y axis and it will give and slip over the tape if torqued strongly in the z axis.
That said, to each their own.
#19
Senior Member
Join Date: Dec 2005
Location: Boulder, Colorado
Posts: 1,383
Bikes: Cinelli Supercoursa 69, Ritchey Breakaway Cross, Mondonico Diamond Extra 05, Coors Light Greg Lemond (built by Scapin) 88, Scapin MTB, Stumpjumper 83, Specialized Stumpjumper M4, Lemond Poprad 2001
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked 2 Times
in
1 Post
mcoz, here you go.
the straps and platforms holding them bolt onto the basic rack and are not used/installed unless you opt for teh bag as well.
Deanster04, I'm also a mechanical engineer with 24 years in the business and significant experience in composit use. Your statementabout certain failure is misleading and unqualified. If the seat post is built well (i.e not to thin walled) and installed with a rubber/taped sleeve and uniform tightness, I see no reason to worry about post failure as long as the rack is installed with consideration and used responsably. Agreed a carbon tube is weakest in a tortional state but the trick is to assure you don't grip it like a vise. As mine is set up, the lower lip rests on the frame to reduce any bending action in the Y axis and it will give and slip over the tape if torqued strongly in the z axis.
That said, to each their own.
the straps and platforms holding them bolt onto the basic rack and are not used/installed unless you opt for teh bag as well.
Deanster04, I'm also a mechanical engineer with 24 years in the business and significant experience in composit use. Your statementabout certain failure is misleading and unqualified. If the seat post is built well (i.e not to thin walled) and installed with a rubber/taped sleeve and uniform tightness, I see no reason to worry about post failure as long as the rack is installed with consideration and used responsably. Agreed a carbon tube is weakest in a tortional state but the trick is to assure you don't grip it like a vise. As mine is set up, the lower lip rests on the frame to reduce any bending action in the Y axis and it will give and slip over the tape if torqued strongly in the z axis.
That said, to each their own.
#20
Member
Join Date: Aug 2009
Location: MA/ RI Coast
Posts: 36
Bikes: Giant TCX, Schwinn Sierra, Diamondback Outlook
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
What is a composit?
Deanster, your right, no argument or disrespect intended from this end either. Just pointing out that nothing is cut and dry. Your also absolutely right about varying abilities and risk associated with them. ( I spent the first part of my career writing repair procedures for military personnel of widely varying capabilities.) For the record, I offer no intended "blanket" endorsement of the product or install. Just offering that it works for me with the cautions noted.
IMHO,Nobody should attempt repair or alteration of anything beyond their capabilities/knowledge/comfort zone.
Over and out.
#22
Senior Member
How many reading this thread have ever had a carbon seat post break for any reason??
#23
Senior Member
Join Date: Sep 2005
Location: In the foothills of Los Angeles County
Posts: 25,274
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 8273 Post(s)
Liked 9,028 Times
in
4,469 Posts
I was wondering the same thing. I've broken the alloy posts and I saw a friend crash when he broke one, but I don't remember hearing about anyone breaking a CF post, even those using racks.
#24
Time for a change.
Join Date: Jan 2004
Location: 6 miles inland from the coast of Sussex, in the South East of England
Posts: 19,913
Bikes: Dale MT2000. Bianchi FS920 Kona Explosif. Giant TCR C. Boreas Ignis. Pinarello Fp Uno.
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 5 Times
in
4 Posts
However- I used to be a fibre glass laminator and I can tell you that any Fibre glass- Kevlar- or Carbon Fibre product has a great deal of strength in it- but it is liable to break for no apparant reason at any time. Could be a production fault but more likely to be the result of a knock or hit- some time previously. A hard enough hit- and it need not be that hard- and the material starts to delaminate internally. This cannot be seen externally so is very difficult to check visually- until it breaks.
I do have C.F. and even have a C.F. bike and don't worry unduly about it breaking- but If I hear any creaking on tightening- or it gets a hard enough hit- It will be changed.
__________________
How long was I in the army? Five foot seven.
Spike Milligan
How long was I in the army? Five foot seven.
Spike Milligan
#25
Senior Member
Join Date: Dec 2005
Location: Boulder, Colorado
Posts: 1,383
Bikes: Cinelli Supercoursa 69, Ritchey Breakaway Cross, Mondonico Diamond Extra 05, Coors Light Greg Lemond (built by Scapin) 88, Scapin MTB, Stumpjumper 83, Specialized Stumpjumper M4, Lemond Poprad 2001
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked 2 Times
in
1 Post
It's what an engineer gets when we don't hit the spell check one last time
Deanster, your right, no argument or disrespect intended from this end either. Just pointing out that nothing is cut and dry. Your also absolutely right about varying abilities and risk associated with them. ( I spent the first part of my career writing repair procedures for military personnel of widely varying capabilities.) For the record, I offer no intended "blanket" endorsement of the product or install. Just offering that it works for me with the cautions noted.
IMHO,Nobody should attempt repair or alteration of anything beyond their capabilities/knowledge/comfort zone.
Over and out.
Deanster, your right, no argument or disrespect intended from this end either. Just pointing out that nothing is cut and dry. Your also absolutely right about varying abilities and risk associated with them. ( I spent the first part of my career writing repair procedures for military personnel of widely varying capabilities.) For the record, I offer no intended "blanket" endorsement of the product or install. Just offering that it works for me with the cautions noted.
IMHO,Nobody should attempt repair or alteration of anything beyond their capabilities/knowledge/comfort zone.
Over and out.