Anyone used a v-daptor?

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rayms
Posts: 1
Joined: 11 Aug 2022, 2:17am

Re: Anyone used a v-daptor?

Post by rayms »

531colin wrote: 8 Jul 2010, 7:29pm
freebooter wrote:
531colin wrote: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.
What about using non compression link housing for the outer you mentioned?
hamster
Posts: 4131
Joined: 2 Feb 2007, 12:42pm

Re: Anyone used a v-daptor?

Post by hamster »

Holy thread resurrection Batman!

Responding to a comment posted 12 years ago...
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531colin
Posts: 16083
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Anyone used a v-daptor?

Post by 531colin »

rayms wrote: 11 Aug 2022, 2:21am
531colin wrote: 8 Jul 2010, 7:29pm
freebooter wrote:
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.
What about using non compression link housing for the outer you mentioned?
Blimey, only 10 year old thread!
If you mean "compressionless" outer, surely its a pretty cheap and quick experiment to do?
However, as I say, I think the "losses" you get in any Bowden cable running in an outer cable are friction losses, not lost motion....and I think compressionless outer will address lost motion rather than friction?

ImageIMG_5137 by 531colin, on Flickr

Reading back on the 10 year old thread, I was talking about bar end levers. However, as you see above I have now gone for (home made) bullbars....because my hands are now too arthritic to brake from the hoods. That bike is one of 2 which have MTB pull BB7 disc calipers and Vee brake specific drop bar levers. I wondered about using compressionless outer, but the brakes are really excellent with ordinary spiral wound outer.

It just occurred to me that we have some material on the mechanical advantage of various (rim) brake systems ....I think it starts about here...viewtopic.php?t=63112&start=45
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