Drop bar to flaT bar conversion

2poc

Help I need some advice on how to covert a shimano 105 10 speed setup to flat bar 1x10.

I’ll keep the rear mech and brake callipers but what brake levers? What shifter? I’m confused with pull ratios for both the shifting and braking 🤦‍♂️

Would dia compe goldfinger levers work and any old 10 speed mtb shifter?

Thanks in advance and apologies for the slight ramble

akh

I'm pretty sure the last common pull ratio for Shimano road and mountain bike shifters was 9 speed (or earlier), so a MTB shifter won't do (unless you also change the rear derailleur to match). However, Shimano make compatible flat bar shifters for road. Have a look at the compatibility chart here:

https://productinfo.shimano.com/#/com?cid=C-453&acid=C-454

Drop bar shifters have product codes starting ST. The flat bar shifters have the product code starting SL. SL-4600 should do and SJS have them in stock.

https://www.sjscycles.co.uk/gear-shifters-rapidfire-trigger/?brand=shimano&groupset=tiagra

Only seem to come in silver though. The newer black look nicer, but they won't work with your current rear derailleur. Tiagra 4700 10 speed (which the black ones linked above are part of) use the same pull ratio as the newer 11 speed stuff. If you grab a 4700 rear derailleur too it'll work. There is only one 10 speed cassette spacing for road, so your cassette doesn't need to change.

Up front, any aftermarket single ring should be fine, various brands exist. I've no specific recommendation as I'm using one that's only available for newer 4 arm cranks and haven't tried any others. You don't need anything to keep the chain on if it's a narrow wide chainring in my experience, I've done well over 2k km with a narrow wide and standard rear derailleur without issue.

For brake levers, again Shimano make suitable ones. Compatibility chart here:
https://productinfo.shimano.com/#/com?cid=C-453&acid=C-456

Link here:
https://www.sjscycles.co.uk/brake-levers/shimano-tiagra-bl4700-flat-bar-caliper-brake-levers-222mm-clamp-black/

I've no affiliation with SJS, they just came high up in the Google results and I've used them before without issue, although usually for small consumables (they carry loads of small Shimano parts and spares that Wiggle don't).

akh

I just spent ages on a detailed post but the forum seems to have eaten it.

I can't be bothered to type it again sorry, the simplified version is below.

No you can't use a MTB shifter, but Shimano make road ones anyway.

https://www.sjscycles.co.uk/gear-shifters/shimano-tiagra-sl4600-10-speed-rapidfire-shift-levers-for-flat-bar-double/

https://www.sjscycles.co.uk/brake-levers/shimano-tiagra-bl4700-flat-bar-caliper-brake-levers-222mm-clamp-black/

Newer and slightly nicer looking shifters are available, but if you want compatibility with a 105 5700 rear derailleur those are the ones you need.

Up front, any narrow wide chainring that is compatible with your cranks should be fine. You do need narrow wide or the chain won't stay on. You don't need a rear clutch derailleur though, I've ridden over 2k km on a narrow wide with standard R8000 rear derailleur and never dropped the chain.

You don't have to take my word for compatibility, Shimano publish detailed charts you can cross reference what I've said here:

https://productinfo.shimano.com/#/com?cid=C-453&acid=C-454

https://productinfo.shimano.com/#/com?cid=C-453&acid=C-456

I'm assuming your on a full 105 5700 groupset, if not check the parts I've recommended are suitable for your actual brakes and rear derailleur.

akh

I have a bit more time now.

Shimano also make 2 other shifters that will work, but availability and/or pricing seems to be worse. No idea what the cosmetic or feature differences are, I've not researched it that much.

The shifters I linked do include the front shifter, which you've indicated you don't need. Not sure if any UK stores have a better price or offer single shifters. SJS was just the top UK Google hit from a store I've used and so didn't mind recommending.

You can buy the individual rear shifter for less than half the price from Germany, although postage is about €10. You might also have to pay a small foreign currency transaction fee if you're UK based (depending on your bank or credit card provider). I've seen bike discount mentioned on this forum as reputable, but I've not used them personally.

https://www.bike-discount.de/en/buy/shimano-tiagra-sl-4600-10-speed-flat-bar-shift-lever-right-885746

There are multiple suitable brake levers. I can't see how one could be much better than the others. I just picked the top one on the Shimano chart to search for.