Blackburn Rack Bending
#1
Blackburn Rack Bending
Looking for a little help a whether these racks can be bent without damage. I purchased this Blackburn rack and it's from a 22.5" frame. I'm putting it on a 21" frame and the seat stay section of the rack is too wide for my frame. I need to reduce the width about 5-7mm. Anyone ever bend one of these with luck? Is there anything special I should do before attempting to vice them in a bit? Would heating over a flame and bending while the rack is warm lessen the chance of breakage?
Thanks to all in advance.
Thanks to all in advance.
#2
Banned
the difference between annealing and melting aluminum is small .
and just warm is meaningless , annealing metals happens at about the temperature, they glow
hard to see when that is reached but in near dark,
there are other racks with adjustable stainless steel struts ,
copies of the older blackburn racks that may fit better for your needs.
and just warm is meaningless , annealing metals happens at about the temperature, they glow
hard to see when that is reached but in near dark,
there are other racks with adjustable stainless steel struts ,
copies of the older blackburn racks that may fit better for your needs.
#3
the difference between annealing and melting aluminum is small .
and just warm is meaningless , annealing metals happens at about the temperature, they glow
hard to see when that is reached but in near dark,
there are other racks with adjustable stainless steel struts ,
copies of the older blackburn racks that may fit better for your needs.
and just warm is meaningless , annealing metals happens at about the temperature, they glow
hard to see when that is reached but in near dark,
there are other racks with adjustable stainless steel struts ,
copies of the older blackburn racks that may fit better for your needs.
#5
Senior Member
Likes For bradtx:
#6
Right now the rack seat stay attachments line up with the center of the seat stay tubes. I need them on the inside of the stays to attach them to the braze-on's. I need to move them together to get them to bolt on.
#7
Senior Member
How much money do you have in the rack? If my eyes aren't fooling me, those struts appears to be solid aluminum. That alone will make them much easier to bend than if they were tubular. Basically, if you don't have a ton of money in it, I'd go ahead and try to bend it. You don't have much to lose. Worst case it breaks and you buy a new, better designed, rack that will fit without issue.
I wouldn't bother heating the aluminum. If it's heat treated aluminum, you'll ruin the heat treatment if you get it hot enough to make a difference. If it's not heat treated, it'll bend readily without heat. Most people caution about bending aluminum because frames are all heat treated to a T6 temper or higher. At that temper, aluminum won't bend far before it cracks. At T0, 6061 bends very easily.
I wouldn't bother heating the aluminum. If it's heat treated aluminum, you'll ruin the heat treatment if you get it hot enough to make a difference. If it's not heat treated, it'll bend readily without heat. Most people caution about bending aluminum because frames are all heat treated to a T6 temper or higher. At that temper, aluminum won't bend far before it cracks. At T0, 6061 bends very easily.
Last edited by joejack951; 09-12-13 at 07:27 AM. Reason: added an "if"
Likes For joejack951:
#8
Mechanic/Tourist
I have bent Blackburn racks to fit, but bending is going to be problematic, as you will need a double bend to make the ends parallel to the braze-ons and you don't have a lot of length to deal with. You could also ignore the braze-on mounts and use a P clip or get a rack that will fit properly and resell that one.
Last edited by cny-bikeman; 09-12-13 at 08:08 AM.
#11
Thanks to all. I'll try the double bend doing the tips first. Ill go slow and if it doesn't look like its going to go well, I'll stop.
#13
Senior Member
Bending 3.5mm per side is nothing for these racks. Most bikes will have to have these Blackburn racks bent a little to fit. Contact Blackburn if you want the most cautious answer and I'm sure they will say it's OK.
#14
Senior Member
Why not fit them to the outside of your eyelets? Just spread the legs out 3mm and they will spring back, no ned to permanently bend them . I think I did this with one of my racks, many years ago and it is still working.
#15
Senior Member
The discussion is about the top two attachment points that run to the seat stays.
#16
SE Wis
Join Date: Apr 2005
Location: Milwaukee, WI
Posts: 10,811
Bikes: '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400, 2013 Novara Randonee, 1990 Trek 970
Liked 3,655 Times
in
2,201 Posts
I've used spacers mostly to clear the brake on this install.
#17
Soft jaws was something I would have overlooked. Great input and thanks. The rails are solid aluminum so it's good to hear positive comments about bending. I plan on attempting this over the next month and will post pictures upon completion.
#18
Not quite there yet
Join Date: Feb 2013
Location: Monkey Bottom, NC
Posts: 999
Bikes: A bunch of old steel bikes + an ICE trike
Likes: 0
Liked 2 Times
in
2 Posts
I have 2 old Blackburn racks and have used them on a number of different bikes. Each time I would make some bends to customize to the new frame, both to spread/compress or level the rack. I have never had any issues at all. The rack I am currently using on my commuting bike has ~ 30 years use. 5-7 mm is nothing - go for it. Remember - slow and steady pressure is what you are after.
Good luck
Good luck
#19
Newbie
Join Date: Jun 2021
Posts: 1
Likes: 0
Liked 0 Times
in
0 Posts
Looking for a little help a whether these racks can be bent without damage. I purchased this Blackburn rack and it's from a 22.5" frame. I'm putting it on a 21" frame and the seat stay section of the rack is too wide for my frame. I need to reduce the width about 5-7mm. Anyone ever bend one of these with luck? Is there anything special I should do before attempting to vice them in a bit? Would heating over a flame and bending while the rack is warm lessen the chance of breakage?
Thanks to all in advance.
Thanks to all in advance.
#20
Droid on a mission
Join Date: May 2018
Location: Palm Coast, FL
Posts: 1,069
Bikes: Diamondback Wildwood Classic
Liked 315 Times
in
221 Posts
You may not get an answer as this is a zombie thread from 2013
__________________
JoeTBM (The Bike Man) - I'm a black & white type of guy, the only gray in my life is the hair on my head
www.TheBikeMenOfFlaglerCounty.com
JoeTBM (The Bike Man) - I'm a black & white type of guy, the only gray in my life is the hair on my head
www.TheBikeMenOfFlaglerCounty.com
Likes For JoeTBM:
#21
Must be symmetrical
Use a long bolt and spacers. Blackburn racks used to come with aluminum spacers for such purposes.
Doing so will put some leverage on the braze on, and the bolt, if not completely tight, will wiggle in the braze on, loosening more and doing damage. Whenever i need to space out a rack, I install a long bolt from the inside out, so it is screwed tightly against the braze on. For extra piece of mind, fasten a nut from the other side. Then you have a length of bolt really securely attached. Use spacers or washers, then the rack, then a washer and a nut.
Doing so will put some leverage on the braze on, and the bolt, if not completely tight, will wiggle in the braze on, loosening more and doing damage. Whenever i need to space out a rack, I install a long bolt from the inside out, so it is screwed tightly against the braze on. For extra piece of mind, fasten a nut from the other side. Then you have a length of bolt really securely attached. Use spacers or washers, then the rack, then a washer and a nut.
#22
Must be symmetrical
Use a long bolt and spacers. Blackburn racks used to come with aluminum spacers for such purposes.
Doing so will put some leverage on the braze on, and the bolt, if not completely tight, will wiggle in the braze on, loosening more and doing damage. Whenever i need to space out a rack, I install a long bolt from the inside out, so it is screwed tightly against the braze on. For extra piece of mind, fasten a nut from the other side. Then you have a length of bolt really securely attached. Use spacers or washers, then the rack, then a washer and a nut.
Doing so will put some leverage on the braze on, and the bolt, if not completely tight, will wiggle in the braze on, loosening more and doing damage. Whenever i need to space out a rack, I install a long bolt from the inside out, so it is screwed tightly against the braze on. For extra piece of mind, fasten a nut from the other side. Then you have a length of bolt really securely attached. Use spacers or washers, then the rack, then a washer and a nut.
#23
2-Wheeled Fool
Join Date: Sep 2016
Location: New Hampshire
Posts: 2,346
Bikes: Surly Ogre, Brompton
Liked 677 Times
in
457 Posts
Looking for a little help a whether these racks can be bent without damage. I purchased this Blackburn rack and it's from a 22.5" frame. I'm putting it on a 21" frame and the seat stay section of the rack is too wide for my frame. I need to reduce the width about 5-7mm. Anyone ever bend one of these with luck? Is there anything special I should do before attempting to vice them in a bit? Would heating over a flame and bending while the rack is warm lessen the chance of breakage?
Thanks to all in advance.
Thanks to all in advance.
#24
Generally bewildered
Join Date: Aug 2015
Location: Eastern PA, USA
Posts: 3,038
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
Liked 342 Times
in
252 Posts
If you had to bend 6061, you would need to heat it with a torch.
Ahhhh. A zombie thread! I was sucked in!
Last edited by WizardOfBoz; 01-31-22 at 08:45 AM.