Thorn Front Fork with Reverse Brake Mount Setup Question (Canti's)

[BarryEvans]

Hi,

I have recently purchased my first Thorn and to say I'm pleased with my purchase is an understatement! It is an absolutely fantastic bike to ride. However, I do have a problem with setting up the Reverse mounted front brake. I have pictured the current way I have attempted to set it up, but it's not right, in this setup the r/h canti forces the rim across to the l/h canti when the lever is pulled (the r/h canti does all of the work). Unlike in the conventional setup where both canti's actuate in order to "clamp" onto the rim.

I have tried searching the internet and this forum for information but to no avail, hence creating this post on the Thorn forum (I'm sure someone on here still uses canti's on reverse fork mounts). If anyone can shed light on the matter, it would be highly appreciated.   




I bought the bike partially dismantled, the previous owner didn't know how the brake should be setup.


All the best and thanks in advance!

[rualexander]

That's a pretty weird brake set up. Never seen cantis used on that position before or in that fashion.
The Thorn bikes with reverse brake mounts like that usually use V brakes so I'm not sure why the previous owner would have fitted cantis there. What type of brake levers are fitted? Cantis and V brakes use different brake levers so you need to know what the levers you have are designed to be used with.
Looking at the pictures, I'm guessing that the triangular plate pivots around the central bolt attaching it to the fork crown, so that when you pull the cable and the left brake moves towards the rim, the plate pivot and pulls the right brake towards the rim too, but I might be wrong in guessing that? If the plate doesn't pivot, then I can't see how these will ever work.
In any case, it is weird.

[BarryEvans]

Thanks for your prompt response!

It is certainly very weird, although I have seen canti's setup on reverse mounts with the same suntour canti's on a Thorn Adventure tandem that SJS were selling on ebay not too long ago. Unfortunately the pictures in the ebay listing don't show how it is all "wired" up

Here's the ebay links:

http://www.ebay.co.uk/itm/THORN-ADVENTURE-531-STEEL-BIKE-BICYCLE-TANDEM-S-S-22127-/170437742626

http://www.sjscycles.com/ebay/22127thorn.jpg

Not sure on the exact lever model, but they're some Tektro branded ones fitted on straight bars. Although I could have a closer look and try to find out if necessary but I'm pretty sure they're meant for canti's as the back brake (conventional canti setup) works really nicely.

It does pivot around the centre bolt, and I do believe the way you stated is the manner in which it should operate. However in the setup pictured, when the lever the pulled the r/h brake is actuated (as you'd normally expect) but there is very very little actuation in the triangular plate so the l/h brake only moves very slightly. Instead the braking occurs through the r/h brake forcing the rim over toward the l/h brake. As it is currently setup, the brake will stop you, but I can't believe it would perform this poorly when compared against the rear.

I'm not sure whether my cable routing is correct/wrong, or if it is correct then whether my brake setup is wrong?

This is last issue to be resolved on the bike, and I can't wait until it is fixed as the rear brake is fantastic (imho) and if the front can match that stopping power I'd be very happy.

Thanks again for your help  

[julk]

I am probably complete wrong here,
but try the pivoting metal plate horizontal with the brake outer coming from above the pivot to the right side and the left cable shortened a bit to fit. I think that will then stand a chance of working.

[bobs]

If you have straight bars swap them for Vee brakes they are far better.

Bob

[BarryEvans]

Hi again,

Thanks Julk, tried that but to no avail unfortunately.

I did some more research into the matter and found that Thorn did once offer (and may still do) some sort of solution to allow you run these 'self energising' on the reverse mounted front forks and I believe that I only have part of their solution and something is missing from my setup. Unfortunately the link to the brochure in which the solution was offered is dead so I'm unable to find out from that what is missing:

http://www.cyclingcrowd.com/Uwe/Forum.aspx/uk-bicycle/11254/Suntour-XC-self-energising-Pedersen-design-cantilever-brakes

However, rather than trying to find out what is missing I think I'd much rather just 'upgrade' to Vee brakes (as Bobs suggested), as it seems like the easier and more worthwhile option considering the general internet forum consensus that these 'self energising' brakes aren't as good as many of Vee brakes on offer.

On to my next question!

I have a set of Avid SD5's or maybe 7's (can't remember) with matching Avid levers removed from an old MTB I had bought for spare parts that I may use. I've never tried these brakes out (although they're in excellent condition), anyone had any experience with these? Are they any good? Do I need any specific parts to fit the front Vee brakes to the reverse mounts on the front forks? Are they compatibable or will I need to buy a different set of Vee brakes?

Thanks again for all of your help!
  

[freddered]

What a Dog's Dinner of a set up that is.

As above, swap them for V-Brakes.

Any V-Brakes should work.  One benefit of the reverse mounting is that the cable run will be better.

[BarryS]

Hi,
I had this setup on a tandem, since sold, and once setup correctly worked very well.
You need at least three hands to do it.

Have a look at this pic which is a good guide to how it should be, so I think you have all the parts ( but try adding a vbrake noodle to lead in the cable at a reliable angle)

http://www.flickr.com/photos/baznewpics/4517669360/sizes/l/in/set-72157623845213936/.

As with all canti setups, I found it best to remove tyre and mudguard so you can clearly see the movements and gaps for toe in etc.

Barry