V-Brakes & STI's

[davester65]

Hey Guys,

I'm sure this topic will have been covered before so if anyone has experience of this or can point me to the relevant thread that would be great, thanks.

I'm in the process of converting my flat bar bike (see http://www.cyclechat.net/threads/show-us-your-mix-match.121541/ ) to drop bars.

New shifters are Sora 3503 STI, original brakes are Deore M590 V-Brakes....not a good combination...i've found out, lol.

Some quick googling has revealed that STI's and v-brakes are generally not compatible, but there are a couple of options........Travel Agents fitted to the V-Brakes or New Canti Brakes.......or does anyone know a better solution?

 

[Davidc]

Caliper brakes also work with STIs.

 

[davester65]

@ Adrian, disk brakes not an option as frame. forks and wheels are not compatible :-(

@ Davidc, caliper brakes are another option but as frame and forks have canti / v-brake bosses i think it would look a bit odd with caliper brakes.

 

[Davidc]

@ Adrian, disk brakes not an option as frame. forks and wheels are not compatible :-(

@ Davidc, caliper brakes are another option but as frame and forks have canti / v-brake bosses i think it would look a bit odd with caliper brakes.

I've just replaced cantis on my tourer, and still have the bosses there, with self amalgamating tape protecting them. Do look a bit odd though, so might eventually saw them off and paint over the cuts. The (dual pivot) calipers are quiet and work a lot better so the cantis won't be going back on. I'll get round to doing the back ones sometime.

I have thought about using the bosses for lights.

 

[Dave Davenport]

I fitted V brakes with a travel agent to Mrs D's Tricross to replace the Tektro canti's which were a bit rubbish, especially for someone with small hands. They don't work quite as well as V's with proper levers but they're not bad.

 

[davester65]

Thanks guys, after a couple of hours tinkering and adjusting this morning i have the standard v-brakes working with the sora sti's, with about the same amount of travel as my road bike which has microshift sti's and dual caliper brakes. Still not happy with them though as the braking power is nowhere near as good as the caliper brakes, it would be very scary having to brake hard on a descent!!
So i did some more googling and found out that mini V-brakes are compatible aswell so i now have the choice of travel agents, canti's or mini v's (or only ride where it's pan flat! lol )

 

[davester65]

Decision made, tekro mini v's bought and fitted.....only concern was tyre clearance but no problem with the 35mm Conti tyres fitted, all in all a HUGE improvement, just been out for test ride and plenty of stopping power. One more issue to deal with, Deore front derailleur not compatible with STI's due to different pull ratio so Sora triple FD on order, then conversion complete. :-)

 

[cyberknight]

How would disc brakes fair with sti? i like the idea of converting my subway but it has dics and 8 speed triple.

 

[davester65]

Don't see why not, there's plenty of road & cyclocross bikes out there with disc brakes as standard, guess it will depend on the pull ratio.
Would guess you will need a new front derailleur though as road triples and mtb triples work on different ratios.
I'm sure some of the guys on here will be able to offer up plenty of info.

 

[RecordAceFromNew]

Decision made, tekro mini v's bought and fitted.....only concern was tyre clearance but no problem with the 35mm Conti tyres fitted, all in all a HUGE improvement, just been out for test ride and plenty of stopping power. One more issue to deal with, Deore front derailleur not compatible with STI's due to different pull ratio so Sora triple FD on order, then conversion complete. :-)

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Please don't be surprised if It does not go as well as you have intended - mtb and road chainsets and therefore fd generally aren't set up for the same chainline, with the former being 47.5mm or 50mm usually, while road is 45mm. The implication is you might have trouble with the sora mech reaching for the outer ring, and I don't know what chainset you have but mtb and road fd usually have different ring size assumptions through different mech profile too. But you might be lucky and it works tolerably. If not, come back before jumping into other changes.

 

[RecordAceFromNew]

How would disc brakes fair with sti? i like the idea of converting my subway but it has dics and 8 speed triple.

Not with existing disc brakes, which have V brake cable pull ratio. You will have to replace it with road version of e.g. bb7, and the same issues as davester65 has with fd/chainline will arise if you are using sram/Shimano sti's. Some versions of Campag sti's may fair better, especially if you pick a 10 speed one which happens to pull the right amount of cable for Shimano rear mech for 8 speed, if you have a Shimano rear mech.

 

[davester65]

Please don't be surprised if It does not go as well as you have intended - mtb and road chainsets and therefore fd generally aren't set up for the same chainline, with the former being 47.5mm or 50mm usually, while road is 45mm. The implication is you might have trouble with the sora mech reaching for the outer ring, and I don't know what chainset you have but mtb and road fd usually have different ring size assumptions through different mech profile too. But you might be lucky and it works tolerably. If not, come back before jumping into other changes.

Thanks, good info. Did speak to my brother about this earlier as he's into touring bikes, he pointed me to a thread on the CTC forum which deals with this topic.
http://forum.ctc.org.uk/viewtopic.php?f=5&t=60930

The crux seems to be that with a road triple fd, although a 45mm chainline is preffered, they will work with a 47.5mm chainline. My Dolan chainline is currently set at 50mm but this can be changed to 47.5mm by switching the BB cup spacers. So i'm fairly confident the Sora FD will work.

 

[davester65]

Please don't be surprised if It does not go as well as you have intended - mtb and road chainsets and therefore fd generally aren't set up for the same chainline, with the former being 47.5mm or 50mm usually, while road is 45mm. The implication is you might have trouble with the sora mech reaching for the outer ring, and I don't know what chainset you have but mtb and road fd usually have different ring size assumptions through different mech profile too. But you might be lucky and it works tolerably. If not, come back before jumping into other changes.

Thanks RAFN, this post really got me thinking, if the correct size fd (31.8) would be expecting a chainline of 45mm and i could only achieve a chainline of 47.5mm at best, it could still struggle to change to the top ring correctly. Then i thought about how to move the fd a couple of mm so i changed my order to a 34.9 fd and used the existing shims when i fitted the new fd to gain an extra 1.5mm. Happy to report it works great and have full range of gears.

 

[RecordAceFromNew]

Happy to report it works great and have full range of gears.

Glad to hear! If your fd shim is concentric which I think they generally are I don't think it would have changed the fd's reach, and I think within the same model Shimano fd's don't have different reach for variants with different clamp size.