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Old 02-08-14, 09:30 PM   #1
bobotech
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Converting a cross bike to disc brakes, but want to use MTN calipers

I did a little computer work for one of my computer clients who owns a bike shop. In exchange he gave me a pair of Shimano mechanical disc brake calipers which I know won't work very well with my Ultegra 9 speed shifters.

This conversion is for my Motobacon Fantom Cross Team Ti that has disc brake tabs. I'm doing this as a budget build. I so far have 44 dollars into the rims (Mavic A119 32 hole touring rims, I'm a big guy and wanted strong rims), 25 dollars for new spokes, and that is it for now. All the rest of the parts (disc brake hubs, discs, etc) are all stuff I had in my stock of spare parts. And my time for the calipers.

Now I know that the Ultegra shifters won't work well with the mountain disc calipers but I have a pair of V-brake travel agent adapters at my disposal. Do you think it would be possible to use the travel agents (not the inline models but the noodle replacement models) to allow the cable pull to be correct for the mtn disc calipers?
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Old 02-08-14, 09:48 PM   #2
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It is possible since cable forces are similar to the v-brake design that they were intended for. I did a road-bike style disc on my commuter mtb to go with road levers. On that unit I got a set of Avid BB5 road calipers and everything else(rotors, wheels, hubs) was mtb. The mtb caliper motion ratio will favor the caliper operation compared to the road version, which has been rather sensitive to cable adjustment having such a small cable pull.
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Old 02-09-14, 07:08 AM   #3
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I think that you're likely to have trouble getting the V-brake Travel Agents to work on disc brakes. The issue is the V-brake units are designed to replace the noodle so the cable makes a right turn.

FWIW, I'm a fan of using compressionless brake housing, like Jagwire Rip Cord, for mechanical disc brakes. I think that it's a huge improvement over common spiral wound brake housing. I wouldn't bet on it being enough different to work with road style brake levers but, if it was my bike, I'd give it a try before spending money on new calipers or in-line Travel Agents.
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Old 02-09-14, 10:34 AM   #4
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Well I already have the travel agents. I bought them a while ago for another project but never used them. I will see if I can get them to work. If not, then I will be back to wheeling and dealing to trade the mtn calipers for a pair of road calipers.
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Old 02-09-14, 11:05 AM   #5
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In terms of pull they will work. Whether you can find a good spot to stick them is another question. I've places TAs right where the cables exit the bar tape with decent results once. I had to make a sort of double sided ferrule thingy though to hook it all up.
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Old 02-09-14, 10:09 PM   #6
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In terms of pull they will work. Whether you can find a good spot to stick them is another question. I've places TAs right where the cables exit the bar tape with decent results once. I had to make a sort of double sided ferrule thingy though to hook it all up.
Well yup, they do work.

I mounted the front TA up by the front cross brake lever and mounted the rear TA on the rear caliper itself. I just made a loop of housing from the rear TA to the cable exits.

Appears to work fine. You really can't tell that the front one has one but the rear setup does look a tad "odd" but for not putting out any more cash? I'm down with that.
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