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I have a Specialized Allez 2010 road bike which I want to convert to a flat bar. I have done some research and as a newbie, bit confused about the compatibility.

What I have currently
Rear D: Shimano Claris
Cassette: Shimano 8 speed 13-26
Front D: Shimano Claris
Chainring: 39/52
Brakes: Shimano Claris R-2000
Shifter: Shimano Claris 2/8 Speed

I want to change it to the following
Brake levers: Shimano Sora R-3000/Tiagra/Deore BL-T611
Cassette: Shimano HG-50 9 Speed 12-25

I want to keep the chainrings and Front D as they would be more expensive to replace. My question would be if this new config is possible. Otherwise, I will go for a more simple setup with only changing to Claris ST-RS200/-RS203 Gear/Brake Lever. It will cost me quite the same but less hassle. On the other hand, I am thinking if I am spending money why not upgrade to a new setup as I am also changing the wheels which have a 10-speed hub.

https://www.specialized.com/gb/en/allez-double/p/23428?color=35714-23428

I would really appreciate some advice.

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  • What are the brakes on your bike right now? Rim or disk brakes? R2000 implies rim, being bike.shimano.com/en-EU/product/component/claris-r2000/…
    – Criggie ♦
    Aug 23, 2022 at 1:12
  • Have you felt the need to ride your bike at a more constant cadence regardless of which speed you ride? If not, I would certainly go with the easy route and keep it 8 speed. Personally, only on my road bike (2x11 speed) am I quite picky on cadence, not so much on my MTB (1x12 speed) and commuter (1x10 speed & 1x3 speed) as cadence changes are much less noticeable in those riding contexts.
    – Superman.Lopez
    Aug 23, 2022 at 4:01
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    Also, if you not have done so already, please read questions on this website around converting dropbar to flatbar and consider adjusting the reach with a different size stem.
    – Superman.Lopez
    Aug 23, 2022 at 4:01
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    @Superman.Lopez I have 2 road bikes exactly same config but different color. During Covid while commenting I had a fall and my left shifter broke. So, instead of buying a new shifter I planning to convert to a flat bar road bike for commuting. I don't feel any difference really of 8 or 9 speed. For an amateur cyclist I don't think it matters. My decision to convert is based on to see this as challenge if I can do it. My question is if this will create some kind of road hazard?
    – Maruf I
    Aug 23, 2022 at 18:43
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    @Criggie R-2000 rim brake.
    – Maruf I
    Aug 23, 2022 at 18:47

2 Answers 2

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Generally it is said that 8 speed derailleurs are compatible with 9 speed shifters as the cable pull should be identical. So that would mean you could replace the shifter and cassette with a 9 speed version without replacing the derailleur. However make sure you also use a 9 speed chain (not yet in your list).

You should do some research in this regards about what peoples experience is in mixing 8-speed and 9-speed, as formally Shimano lists these as incompatible. There is a 15+ year archive of forum posts around this topic (eg this post). I suspect the shifting on the chainrings would be compromised slightly, not sure if you would notice it much.

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

Assuming you have calliper brakes (see Criggie's comment on your question), make sure to buy the Sora or Tiagra brake levers you list, and not the Deore. I expect the Deore to be designed for v-brakes and are not compatible with calliper brakes.

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  • My experience with mixing speed classes of front and rear drivetrains has been positive (10 speed crank with 9 speed rear and front der; 10s crank and 11s front der and rear end). Generally if you stay within one speed class in a mixed drive train, one will enjoy normal function given an otherwise correct set-up. The chain should be the same speed class as the rear drive train. Using a front der of a higher speed than the crank and chain can cause chain rub in some gear combos but a good set up will avoid this minor problem. 2x front der should be used with 2x crank and 3x w/ 3x
    – Jeff
    Aug 24, 2022 at 1:35
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https://bike.shimano.com/en-EU/product/component/deore-t610/BL-T611.html
says that they are for V brakes or mechanical disks. Since you have caliper brakes then the pull is wrong and you'll have problems dialling in the travel and bite point. You will require flat-bar brake levers for calipers, like Shimano BL-R780

Your cheapest option is to use a Claris 8 speed shifter for flat bar,
https://bike.shimano.com/en-EU/product/component/claris-2400/SL-2400-R.html
and a 2 position left-hand shifter, retaining the front derailleur
https://bike.shimano.com/en-EU/product/component/claris-2400/SL-2400-L.html

Also consider that your position changes on a flat bar, so you might need a new stem as well as bar.

The risk here is that one change may force another, and another then suddenly your total costs skyrocket.

Regardless - do clean and store and label all the takeoff parts so you or a future owner can revert if they choose.

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