Need help - touring conversion

Mickey1980
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Joined: Sun Jul 10, 2016 9:50 pm

Need help - touring conversion

Postby Mickey1980 » Sat Feb 17, 2018 12:04 am

Hi all!
I have an old Giant Prodigy bike that I want to convert to a drop bar tourer for my father. It currently runs a flat bar setup with Shimano 400cx components and cantilever brakes. My thoughts are to put in Sora STI 3x8. As the frame seems to have a MTB legacy, all the wirings goes along the top tube. Hence the front derailleur is a top pull. I have heard that still can be used with MTB front mech with an adjuster. Question - will it work with the top pull mech? Also, would it make sense to swap the rest of the drivetrain to Sora that I have handy?
Appreciate your thoughts and advice!

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Thoglette
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Re: Need help - touring conversion

Postby Thoglette » Mon Feb 19, 2018 2:34 pm

Eight speed shimano shifting is all the same in terms of pull, (IIRC), even top pull.

You're going to want to run 32 cog cassettes and one weeny ring at the front, so keep the current derailleurs if possible.

What tyre size (currently) fits the frame?
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RonK
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Re: Need help - touring conversion

Postby RonK » Mon Feb 19, 2018 3:26 pm

Mickey1980 wrote:Hi all!
I have an old Giant Prodigy bike that I want to convert to a drop bar tourer for my father. It currently runs a flat bar setup with Shimano 400cx components and cantilever brakes. My thoughts are to put in Sora STI 3x8. As the frame seems to have a MTB legacy, all the wirings goes along the top tube. Hence the front derailleur is a top pull. I have heard that still can be used with MTB front mech with an adjuster. Question - will it work with the top pull mech? Also, would it make sense to swap the rest of the drivetrain to Sora that I have handy?
Appreciate your thoughts and advice!

Drop bar levers are not compatible with the pull ratio of MTB front derailleurs. You will have to use bar end shifters, in friction mode for the front derailleur.

Luckily 8-sp bar end shifters are still readily available.

Converting a flat bar bike to drop bars is going to result an long reach since flat bar bikes generally have a longer top tube. It's possible a comfortable reach could be achieved with a shorter stem, but this is something you should consider before committing.

If you choose to continue with the drop bar and bar end shifters, I have available a brand new in box set of Tektro RL520 linear pull drop bar brake levers which will work with v-brakes.
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LG
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Re: Need help - touring conversion

Postby LG » Tue Feb 20, 2018 9:17 pm

RonK wrote:
Mickey1980 wrote:Hi all!
I have an old Giant Prodigy bike that I want to convert to a drop bar tourer for my father. It currently runs a flat bar setup with Shimano 400cx components and cantilever brakes. My thoughts are to put in Sora STI 3x8. As the frame seems to have a MTB legacy, all the wirings goes along the top tube. Hence the front derailleur is a top pull. I have heard that still can be used with MTB front mech with an adjuster. Question - will it work with the top pull mech? Also, would it make sense to swap the rest of the drivetrain to Sora that I have handy?
Appreciate your thoughts and advice!

Drop bar levers are not compatible with the pull ratio of MTB front derailleurs. You will have to use bar end shifters, in friction mode for the front derailleur.

Luckily 8-sp bar end shifters are still readily available.

Not sure if I've just got lucky, but have been able to match shimano 7 speed MTB shifters and road front derailleurs. Might have just been ignorance and good luck! The RD should be fine, if you can't get the FD to work with the shifters, see what bodge option you can sort for routing the cable under the bottom bracket and swap to the sora.
LG = Low Gear

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singlespeedscott
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Re: Need help - touring conversion

Postby singlespeedscott » Tue Feb 20, 2018 9:45 pm

Up to 9 speed sti levers will play with MTB derailleurs, From 10 speed onwards things get a little funky.
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Mickey1980
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Re: Need help - touring conversion

Postby Mickey1980 » Wed Feb 21, 2018 12:50 pm

Thoglette wrote:What tyre size (currently) fits the frame?

It currently runs on 700c 32mm. I might need to swap them, as they have a 7 speed freewheel to be able to utilise the 8/3 drivetrain. Interestingly, the freewheel cogs are rather small by todays hybrid standard, but it has a pretty small chainrings at the front too. Hope to keep the cranks, as I doubt my father would often go beyond 30 kmh on a tourer.

Mickey1980
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Re: Need help - touring conversion

Postby Mickey1980 » Wed Feb 21, 2018 12:54 pm

singlespeedscott wrote:Up to 9 speed sti levers will play with MTB derailleurs, From 10 speed onwards things get a little funky.

Thanks! Never heard of this, but worth trying.

Mickey1980
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Re: Need help - touring conversion

Postby Mickey1980 » Wed Feb 21, 2018 12:56 pm

LG wrote:Not sure if I've just got lucky, but have been able to match shimano 7 speed MTB shifters and road front derailleurs. Might have just been ignorance and good luck! The RD should be fine, if you can't get the FD to work with the shifters, see what bodge option you can sort for routing the cable under the bottom bracket and swap to the sora.

It appears the earlier versions might be interchangeable between road and MTB. Will test :)

Mickey1980
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Joined: Sun Jul 10, 2016 9:50 pm

Re: Need help - touring conversion

Postby Mickey1980 » Wed Feb 21, 2018 1:01 pm

RonK wrote:If you choose to continue with the drop bar and bar end shifters, I have available a brand new in box set of Tektro RL520 linear pull drop bar brake levers which will work with v-brakes.

I was thinking of bar end shifters for this project as I have the tlTektro brake levers (non-briefters). Though I have a set is Sora STUs that just been fully dis-assembled and serviced (credit to the how to post on this forum), so hoped to use them. Also wanted to keep the cantilevers to have that old school touring aesthetics rather than more modern v-brakes ;)

Mickey1980
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Joined: Sun Jul 10, 2016 9:50 pm

Re: Need help - touring conversion

Postby Mickey1980 » Wed Feb 21, 2018 1:46 pm

Interestingly, Sheldon Brown did not distinguish the pull ratio difference between MTB and Road FDs of different speeds. I guess I will test his empirically.

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