Anyone used a v-daptor?

[freebooter]

I saw one of these going cheap on ebay today and decided to give it a try. I think I know how it works but wondered if anyone has tried one and has any tips for setting it up or perhaps would advice not to bother

http://www.sjscycles.co.uk/product-Sach ... air-89.htm

thanks

[531colin]

What are you trying to achieve? These things are an attempt to match V brakes with levers which don't pull enough cable.

[piedwagtail91]

i use a similar device , the travel agent. never had any problems with them in three years and the brakes work well.

[freebooter]

What are you trying to achieve? These things are an attempt to match V brakes with levers which don't pull enough cable.

Unsurprisingly, I want to use a V brake with a road lever.

[freebooter]

i use a similar device , the travel agent. never had any problems with them in three years and the brakes work well.

Thanks for the reply. The travel agent seems to be the more common device now but they are quite expensive. I have also heard that they can damage cables where they change from the small to large roller. Have you ever had problems with that?

One problem I can foresee with the v-dapter is it relies on friction on a relatively small section of roller. I wonder whether there will be an issue with the cable slipping rather than rotating the cam.

[piedwagtail91]

never had any cable problems in the travel agent though i have had a cable snap in the lever . wether or not this is due to the travel agent i don't know, but i've done 25-30,000 miles with the travel agents with only that one breakage.

[531colin]

What are you trying to achieve? These things are an attempt to match V brakes with levers which don't pull enough cable.

Unsurprisingly, I want to use a V brake with a road lever.

Perhaps I could have phrased it better! I'll start from what I think is the beginning.
V brakes stop better than cantis (I think thats generally accepted)
However, the overall mechanical advantage of the two systems can't be very different - you move the lever a couple of centimetres, the pads move a few millimetres. If V brakes had a much greater mechanical advantage than cantis. then either you would have to set the pads a hair's breadth from the rim or you would be in danger of pulling the levers back to the bars. Neither of these are generally reported faults with V brakes.
So what is the reason for V brakes better stopping?
I think its to do with cable pull. Cantis are a high force/short pull system. V brakes are a low force/long pull sysetm.
I think there are significant frictional losses in the canti. cables, and I think these losses occur in the sections where the wire runs in the outer - I dont think there will be significant losses in bare wire runs.
So to get the best from a V brake using one of these adaptors, you need to site the adaptor right next to the lever, to minimise the length of high force/ short pull cable running in outer. However in reality the adaptors fit at best by the handlebar stem, and I think I have even seen some that fit on the brake itself, so all the cable run is high force/short pull.
In conclusion I think if you are stuck with STIs, then you will have to use an adaptor, but you wont get the best from your V brake.
Me, I've gone for the simple life. Bar end shifters so I can use "mountain" front mech. and proper V brake levers.

[freebooter]

Colin, you may be right on the loss of power in the cable. With my current setup I am wondering whether the cheap cable outers I have are compressing under pressure and hence taking some of the force away from the brakes. The high force/short pull you speak of in canti system would compress the outers more than a lower force/high pull system.

Also Vs are much easier to set up than cantis which makes the manufacturers less likely to get unsatisfied customers simply through brakes that aren't optimally set up and need less skill and care in the mass bike assembly lines.

I do know that an old mtb I had a few years ago with cantis had excellent braking but it did, of course, use flat bars with Shimano canti levers. I think many of the problems reported on touring forums are due to people using cantis with drop levers which is really a kludge.

I am also thinking that my problems may be because I can't get the yoke low enough. My bike has 26" wheels and mudguards that have a lot of clearance. Hence, the yoke cannot go very low before hitting the mudguard. Sheldon seems to maintain that usually the lower the yoke the more power.

tbh I had decided just to replace the cable outers, which needs doing anyway, and make do with my brakes as they are. I would like them to be better but the only time they really cause worry is on very steep hills (recent descents down 25% hills were a bit hairy) and just ride taking account of the braking performance. I had planned to swap the bike to trekking bars and flat levers but after sourcing the components and getting the bars I found that I couldn't fit the levers as I wanted and fitted as standard I didn't like the position so I am a bit fed up of trying to make major changes at the moment.

I had rejected using travel agents as there are expensive for a set but saw this v-daptor going cheap on ebay so thought it was worth a try. If it works I will use it on the front and stick with my canti on the rear.

Your idea of bar ends and proper v brake levers is a good one and something else I have considered but I haven't used bar ends before. I had been thinking of this along with swapping to bull bars as I think they may suit me better than drops. But again tweaking fatigue has set in

[531colin]

V brake levers, bar end shifters and compact drops is my full setup. The compact drops bring everything nicely to hand, I recommend them. I thought of bull bars, but the single hand position put me off.
For the price I would take a punt on the adaptor. We had a good look at canti setup on here http://forum.ctc.org.uk/viewtopic.php?f=5&t=33329 and Sheldon is of course right about the straddle wire setting being paramount. Cantis optimally set will have similar mechanical advantage to V brakes ; if your mudguards preclude optimal canti setup, then V brake and adaptor may be superior.

[freebooter]

The adaptor isn't any use. It isn't the same as the ones on the SJS site. Instead of an excentric pulley it has a centric one. Hence there is no increase in the cable pull through the adaptor. The only use I can see for it is a low friction replacement for the normal v-brake noodle.

[Si]

I tried travel agents and didn't really get on with them - not much modulation. I'd grab brakes and nothing would happen, so I'd squeeze a tab harder and all of a sudden the front end would lock up, especially in the wet. The back end was much more manageable. Having said that, I've seen reports of many other people who have got on very well with them, especially on tandems.

For V brakes on drop bar bikes my ideal solution is the Tecktro V-brake specific drop bar levers. These cost less than the travelagents or Vdapters, do a better job and are less hassle to set up. Of course, this means you can't use STI/Ergo, but as I don't anyway that isn't an issue to me.

Having said that, on my roughstuff-tourer bike I have old frog-leg style cantis, and find then just as good as Vs, once set up right. However, I use bullhorns and so get more power through the levers than someone who breaks from the 'tops' on a normal set-up.

[freebooter]

Si, I am thinking that bullhorns are probably the best handlebar for me and it would be a stronger positon to brake with. What levers/shifters are you using on yours if you have cantis?

[Si]

Si, I am thinking that bullhorns are probably the best handlebar for me and it would be a stronger positon to brake with. What levers/shifters are you using on yours if you have cantis?

I have no shifters on one bike and down tube on the other .
One bike has shimano aero levers (road caliper brakes), and the other has some unbranded, cable out the top, old fashioned levers (canti brakes).

bars are both standard drop bars with the drops cut off and the bar turned upside down.

[531colin]

Is this the thimg you are talking about?

This is a whole new can of worms to me, found it on Sheldon! http://www.sheldonbrown.com/cantilever-geometry.html

[freebooter]

Colin, I saw that as well. I think it must be an earlier version to turn cantis into direct pull. The one I got was like the ones in the SJS link that fit to V brakes as a replacement to the noodle. Howver, mine has a centric roller so doesn't increase the cable pull. The only point to it that I can see is reducing friction from the noodle?