Front shifting help

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neilob
Posts: 698
Joined: 31 Jan 2008, 3:58pm
Location: Notts/Lincs borders

Front shifting help

Post by neilob »

I’m converting a Giant OCR road bike to flat bar for my son. Shifters are 9 speed Alivio triple, chainset is FSA 30-40-50. The front mech is a braze on fit currently a Tiagra. I know that the Alivio front shifter isn’t compatible with the Tiagra FD and ideally I need a MTB shifter but my problem is identifying a compatible MTB shifter which is braze on. Do such things exist?
Using a car to take an adult on a three mile journey is the same as using an atomic bomb to kill a canary.
rjb
Posts: 7200
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Front shifting help

Post by rjb »

I did the opposite converting a giant flat bar hybrid to drops. The front mech worked fine across a triple chainset using a pair of 9 speed tiagra shifters, the old ones with washing lines. I would try it first using the mtb shifters before changing the mech. Link here with a another link within. :wink: viewtopic.php?f=5&t=127019&p=1305676&hi ... t#p1305676

someone made a neat widget from some scrap ally to lengthen the front mech actuator arm to make road mechs compatible with mtb shifters.. Theres a pic on this forum but i cant find it at the mo :(
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
slowster
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Joined: 7 Jul 2017, 10:37am

Re: Front shifting help

Post by slowster »

neilob wrote: 13 Jun 2021, 8:06pmmy problem is identifying a compatible MTB shifter which is braze on. Do such things exist?
No.

In the absence of a solution which increases the effective length of the derailleur actuator arm to match the greater length of cable pulled by your MTB shifter, I think you would need to change the left hand shifter for either a Sora shifter (expensive, although because you get both front and rear shifters, you would also end up with a spare rear shifter since 9 speed road and MTB rear derailleurs use the same cable pull), or a LH/front friction shifter that will mount on the bars.

https://www.spacycles.co.uk/m8b0s108p37 ... Bar-Levers

https://www.sjscycles.co.uk/gear-shifte ... left-hand/

https://www.sjscycles.co.uk/gear-shifte ... left-only/
PT1029
Posts: 1744
Joined: 16 Apr 2012, 9:20pm

Re: Front shifting help

Post by PT1029 »

Shimano also do flat bar levers for "road" gear mechs, 9s in Sora is the only choice (in the 2021 line up),
SL-R3030 RAPIDFIRE PLUS Shift Lever (3x9-speed).
Whether you find any available is another matter.
There will probably be NOS previous years levers available from some retailers, in more choices than Sora.
The good news is that flat bar levers are usually a lot cheaper than STI drop bar levers.

I suspect braze on front mechs are the preserve of the road racing community, so (probably) not made in ATB flavouring.
Swapping ATB/road front gears is always hit and miss, the mechs are designed for a specific chain line (ATB and road are 5mm(?) different). Using the wrong chain line for the mech can mess up the indexing as the shifting arms are not quite on the right part of their swing.
Also, ATB front mechs won't be made for a 50t outer, which may throw things out again. So if you give it a try, you'll have a few things in the mix, each of which will not help your indexing.

Edit. Useful info on the post written while I was writing.
djnotts
Posts: 3036
Joined: 26 May 2008, 12:51pm
Location: Nottingham

Re: Front shifting help

Post by djnotts »

Retro mtb thumbies will, being friction (L) and friction or index (R), shift most front and rear mechs up to 3 x 9. Best always to have a set on the shelf!
rjb
Posts: 7200
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Front shifting help

Post by rjb »

Found it. The missing link? A very neat solution from fastpeddler.
viewtopic.php?t=143549
cable3.jpg
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
neilob
Posts: 698
Joined: 31 Jan 2008, 3:58pm
Location: Notts/Lincs borders

Re: Front shifting help

Post by neilob »

Thanks for the expert advice everyone. The solution was actually very simple……I removed the front mech hanger which was fixed to the frame for a braze on fit, and fitted a band on 31.6mm triple MTB mech with a shim. Obviously it left a couple of fixing holes in the frame but they’ve been plugged. So now I have a compatible front shifter which works pretty well. Not perfect but certainly good enough for the 21.5 miles my son is likely to cycle in 2021!
Using a car to take an adult on a three mile journey is the same as using an atomic bomb to kill a canary.
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