Thorn Cycles Forum
Technical => Wheels, Tyres and Brakes => Topic started by: jrclimber on July 18, 2014, 07:13:41 PM
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I built up an Audax Mk3 18m ago and have had some great day rides and sportives. I now want to take it to Spain touring. The pull arm of the Tektro R539 long drop brakes that I fitted (used with Campag Athena levers) is right next to the pannier rack attachment on the R seat stay. The only way I can attach it is using a long bolt and multiple washers which is ugly and I don't feel is very secure. Can anyone recommend any brakes with different geometry that would get round this problem?
Many thanks, John
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photo please i think i hah the same issue. :-\
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OK, being a newbie, I need some help here. I have photos, I can see a "insert image button" option but no idea how to get the photo off my computer into the message. The help files...err...aren't very helpful!
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Long answer: there are some instruction post by Danneaux the Mod that many swear by. Use the search function.
Short answer: reduce the photos to about a 100K each or 800 pixels in the longest dimension, put them on your desktop, drag them into your message. It's that easy.
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Thanks Andre. Couldn't get the drag and drop to work so found the post you referred to and photos now attached
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Why not mount the rack tie bars to the inside faces of the bosses?
Ian
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Why not mount the rack tie bars to the inside faces of the bosses?
Ian
Not possible on Thorn Audax. The rack mount issue has been raised before.
Racks will fit easily if using Shimano deep drop brakes.
Possibly a Thorn design flaw/issue?
John
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yes exactly the same problem with my brakes .
i now attack arms of the rack on the inside.
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Why not John? Bosses are symetrical and threaded all the way through, and most rack stays (certainly Tubus) are malleable enough.
As you say though, deep drop Shimanos would be the money spenders fix here (got them on mine :). Seems a bit uncharitable to call it a design flaw.
Each to his own though.
Happy days
Ian
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Why not John? Bosses are symetrical and threaded all the way through, and most rack stays (certainly Tubus) are malleable enough.
As you say though, deep drop Shimanos would be the money spenders fix here (got them on mine :). Seems a bit uncharitable to call it a design flaw.
Each to his own though.
Happy days
Ian
Ian,
Youask why not possible to attach rack arms to inner edge of lugs?
The distance between the lugs is such that a screw will not feed into the thread.
It is not uncharitable at all! It is possibly a flaw because no matter what manufacturer brake you use, you should be able to use the rack attachments!
John
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The distance between the lugs is such that a screw will not feed into the thread.
Looks to be plenty of room to me, might be tight getting an allen key in to tighten them but not insurmountable.
If in fact John is correct then use longer bolts and fasten the rack tie bars on with nuts on the inside. Not as pretty a job but less hastle than buying new brakes.
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John, I've just done some empirical testing on my Mk3.
M5x12 hex head screws drop in this way with ease. Allen heads would require a short reach key, but otherwise straight forward.
Jags has done it too, and Macspud's way would also work.
How does it help the OP to say a practical, low cost and neat suggestion is impossible?
As for design, Andy has given us double ended bosses that will work with the OP's caliper if the second most obvious assembly method is adopted. Hardly a fair criticism to call that a flaw, surely? Should I complain about rack fitment issues and lack of a cable stop if I chose to fit centre pulls?
Curious
Ian
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Ian i had the problem side bolted on the inside ofthe boss and outside on the right side but it looked terrible ,so i found too bolts that fitted perfect on the inside but a lot of fiddling to tighten them up stil i got it done ok.saying that i would much prefair to bolt rack on the outside ::)
btw my brakes are tectro 720 obviously the shimano is better fit.
jags.
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True Anto the Shimano brake appears to be the one Andy designed the bike to work with. I think you could get away with bolts as short as M5 x8 if using loctite to secure them. These mounts bear almost none of the load on a well triangulated rack. That's why the very light Tubus racks can use only one stay and why two inside mounted ones would be more than adequate for the Audax' rated load.
I've had a thought though :o there may be less space between the mounts on smaller frames like yours and John's as they will be brazed on nearer to the top of the stays where the triangulation will of course bring them closer together. The inner spacing on the 570m/l frame is 27mm.
Happy days
Ian
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ooops never thought of the locktite ::) but then again i dont have the rack on all the time only when i need it .actually i was avbout to buy the shmano brakes when i spotted the tectro on ctc at a great price ah wel how was i to know ;D ;D
cheers ian
anto.
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Thanks for replies. Looks to be plenty of room on my large frame to fix on the inside if I get some hex head bolts.
John
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John, I've just done some empirical testing on my Mk3.
M5x12 hex head screws drop in this way with ease. Allen heads would require a short reach key, but otherwise straight forward.
Jags has done it too, and Macspud's way would also work.
How does it help the OP to say a practical, low cost and neat suggestion is impossible?
As for design, Andy has given us double ended bosses that will work with the OP's caliper if the second most obvious assembly method is adopted. Hardly a fair criticism to call that a flaw, surely? Should I complain about rack fitment issues and lack of a cable stop if I chose to fit centre pulls?
Curious
Ian
Hello!
You should read carefully what I wrote.
I wrote that the design has a flaw.........The frame bolt on will work 'correctly' with Shimano brakes ONLY!
By the way I rode a 550 size which accomodated the rack easily.
The Audax 853 which I sold to 'jags' was too small for me. I did not fit a rack.
John
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Here's a photo of my mk3, size 600, the largest they make.
With the brakes I have fitted, the outside of the rack boss is obscured, but I have had a rack on the bike when I did lejog a few years ago, but that was an older Blackburn Expedition rack with the flat stays with the twist towards the end, and it was just possible to fit the rack ok on the outside of the boss without affecting the brake.
It does seem strange to design the boss location as it is, but maybe there's a reason for it.
In any case fitting the stays to the inside faces of the bosses is a perfectly adequate solution to the issue, i would use the long bolt from the outside with a nyloc nut to hold the stays method.
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lets face it lads they made a booboo eight of an inch higher and it would be spot on ;D ;D
jags.
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Thanks for replies. Looks to be plenty of room on my large frame to fix on the inside if I get some hex head bolts.
John
Photo is not of a Thorn. I have mounted racks on several bikes from the inside. I believe I also ran the rack bolts on my Sherpa for a Tubus Logo EVO on the inside. Not quick to install when you use Locktite (I use blue Locktite on all rack bolts), but it works. The bolts from the outsides are spare bolts that I carry, the countersunk one is for shoe cleats.
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Photo is not of a Thorn. I have mounted racks on several bikes from the inside. I believe I also ran the rack bolts on my Sherpa for a Tubus Logo EVO on the inside. Not quick to install when you use Locktite (I use blue Locktite on all rack bolts), but it works. The bolts from the outsides are spare bolts that I carry, the countersunk one is for shoe cleats.
Mick, is that tidy twist in the rack strut your work or OEM? I'm thinking that not everyone would have the tools/knack for doing metalwork like that, and it's in a place where crude work would be seen daily and niggle constantly.
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Mick, is that tidy twist in the rack strut your work or OEM? I'm thinking that not everyone would have the tools/knack for doing metalwork like that, and it's in a place where crude work would be seen daily and niggle constantly.
OEM. Some racks instead of having a rod attached to the seat stays have used sheet stainless steel.
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Ian i had the problem side bolted on the inside ofthe boss and outside on the right side but it looked terrible ,so i found too bolts that fitted perfect on the inside but a lot of fiddling to tighten them up stil i got it done ok.saying that i would much prefair to bolt rack on the outside ::)
btw my brakes are tectro 720 obviously the shimano is better fit.
I've had exactly the same problem and this is the same way I solved it - attaching the rack on the inside, rather than the outside. Meant I couldn't use an allen key bolt. Does the job but not ideal having to bend the rack to get a nice fit. Such is life!