Tiagra groupset

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Tiagra groupset

Postby richard21172 » Fri Oct 25, 2013 7:31 pm

Hi have a Scott speedster 50 with the following spec:-
• Bottom Bracket: Shimano Square BB UN26
• Front Derailleur: Shimano FD-2303
• Rear Derailleur: Shimano Sora RD-3500, 24 speed
• Shifters/Brake Levers: Shimano ST-2300, Dual Control 24 speed

I have found the Tiagra groupset at a very reasonable price and want to upgrade ( for various reasons ) however I am a little worried that the bottom bracket will not be compatble.

I believe the Tiagra one is a standard british 68mm and I am told the one currently on the bike is 73mm which is more MTB.

I have been told it will definitely be OK but I have also been told it won't. I am pretty new to this so need help please
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Re: Tiagra groupset

Postby Brucey » Fri Oct 25, 2013 7:52 pm

your BB shell will be 73mm or 68mm. Act accordingly.

In the worst case you will need a new BB to go with your new chainset. They are not expensive, and there is usually one to match most frame and chainset combinations.

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Re: Tiagra groupset

Postby cycleruk » Fri Oct 25, 2013 8:54 pm

You can measure it.
Just put a tape across the faces of the BB shell. 68 or 73? it will be obvious. :roll:

P.S. Which model of Tiagra are you getting. The latest ones are "Hollowtech 2" and are a different system.
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Re: Tiagra groupset

Postby richard21172 » Fri Oct 25, 2013 9:26 pm

I emailed Scott and they said it was 73mm shell but Merlin cycles (where I am looking to buy the groupset) said it would fit. This is what I don't understand.

This is the groupset http://www.merlincycles.com/bike-shop/r ... upset.html

Not much info on the bottom bracket
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Re: Tiagra groupset

Postby cycleruk » Fri Oct 25, 2013 9:59 pm

Like I said you can measure the BB width very easily.

Shimano tech' document says 68 or 70mm BB width so I don't know about 73mm :?:
http://techdocs.shimano.com/media/techd ... 746319.pdf

Also:-
http://techdocs.shimano.com/media/techd ... 753743.pdf

This chainset is the new Hollowtech type and very easy to install.
As long as the left crank is fully seated on the shaft then there should be no problem.
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Re: Tiagra groupset

Postby richard21172 » Fri Oct 25, 2013 10:15 pm

Just measured the frame width and its 68mm so I guess it will fit ? ?
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Re: Tiagra groupset

Postby Brucey » Fri Oct 25, 2013 10:19 pm

yes, no problem.

Note that if this is the first external bearing BB you have fitted in that frame, you might want to have the BB shell faced off so the bearings sit square.

cheers
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Re: Tiagra groupset

Postby richard21172 » Fri Oct 25, 2013 10:22 pm

Never done it before but I was thinking of fitting the whole groupset myself. Starting to think that might not be a good idea now :?
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Re: Tiagra groupset

Postby cycleruk » Fri Oct 25, 2013 11:22 pm

richard21172 wrote:Never done it before but I was thinking of fitting the whole groupset myself. Starting to think that might not be a good idea now :?


Most parts are a straight swap. You will of course need the correct tools for the various jobs.

Cassette = chain whip and cassette tool.
http://www.chainreactioncycles.com/x-to ... -prod10184
http://www.chainreactioncycles.com/cycl ... p-prod7975

Bottom bracket bearings = large special spanner.
http://www.chainreactioncycles.com/s?q= ... t=pricelow

Hollowtech installation tool- but may come with chainset?
http://www.chainreactioncycles.com/shim ... p-prod3785

Chain tool = http://www.chainreactioncycles.com/park ... p-prod7843
just make sure it is suitable for 10 speed chains.

I would also get a 10 speed "quick-link" or "missing link"=
http://www.merlincycles.com/bike-shop/m ... links.html

Check if the front derailleur is the same fixing as your current one. (band-on or braze-on?)
Does the groupset include new cables (brake and gears) ?

You will also need=
New bar tape.
Some grease.
Set of hexagon Allen keys.

You will need these tools for any future maintenance anyway.
You could ask Merlin if they will do a deal for the tools if you need them. :wink:
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Re: Tiagra groupset

Postby richard21172 » Fri Oct 25, 2013 11:39 pm

Thanks cycleruk. Starting to think if its worth the time, effort and money just to switch from a triple to compact :?
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Re: Tiagra groupset

Postby richard21172 » Sat Oct 26, 2013 8:43 am

Bearing in mind my spec

• Bottom Bracket: Shimano Square BB UN26
• Front Derailleur: Shimano FD-2303
• Rear Derailleur: Shimano Sora RD-3500, 24 speed
• Shifters/Brake Levers: Shimano ST-2300, Dual Control 24 speed

Can I not just change to double shifters and change the crankset to a compact ? Will the derailleurs be OK ?
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Re: Tiagra groupset

Postby CREPELLO » Sat Oct 26, 2013 9:49 am

I see no reason why the compact chainset wouldn't work with your existing STI's and front mech. You just re-adjust the cable and end stop screws to make the shifter behave like a double STI.
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Re: Tiagra groupset

Postby Brucey » Sat Oct 26, 2013 9:50 am

the only part of the swap that requires special tools is the BB preparation (which might not be necessary if the frame has been prepped well in the factory]; everything else is no more complicated than routine maintenance would be, it is just that you are doing everything at once.

The Tiagra groupset will all work together as intended; various mix and match options are usually OK, provided the parts you retain are not worn out.

If you want some change that gives lower gears and is inexpensive and durable, there may be other options to consider.

cheers
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Re: Tiagra groupset

Postby richard21172 » Sat Oct 26, 2013 10:10 am

My main issues are:
My current shifters have a thumb changer which I find very annoying especially when on the drops and I want to change gear. I can replace these with the new Claris shifters for £79.99 and they are a direct replacement
I am using a triple. I do sportives and get the feeling that there seems to be a bit of cycling snobbery when it comes to people using a triple. Therefore I was thinking of switching to a compact. 50/34 and 11-30 to give me similar ratios to my triple. However if I change if for a Claris I would need to change the bottom bracket and if I need derailleurs that of course pumps up the cost as well
However once you starting adding it all up you start to question the viability of it. Is it worth it. If I intend keeping my bike for say, 5 years or more I suppose it is. If not then I suppose not.
If I had know my 2300 groupset was pretty much obsolete I would never have bought this bike
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Re: Tiagra groupset

Postby cycleruk » Sat Oct 26, 2013 10:23 am

Having had various triples and doubles, including a current 50/34 compact, then I would stick with the triple.
Although your existing gear will work with a compact there may be slight issues.
1) Does the left STI have a trimming function. I think it does, so that, if the chain rubs the front derailleur then a click on the STI will make a slight shift of to overcome this.
2) Usually a triple front derailleur is wider and also designed to contact the chain at different heights suited to the diameters of the chain rings. A "compact" small ring will be at a slightly different diameter to the granny and middle ring of a triple.
This is not to say it won't work, just that it might not work "sweetly".
3) EDIT) Just thought of another issue. Chain width due to 10 speed chainset with 8 speed components?

Have you seen this special offer by Merlin:-
http://www.merlincycles.com/bike-shop/r ... -sale.html
(This will also require a compatible BB at about £15.)

EDIT - You posted while I was writing this.
Don't let the "snobs" get to you, even the Pro's were using triples on the vicious climbs of this years Vuelta. :D
Last edited by cycleruk on Sat Oct 26, 2013 10:40 am, edited 2 times in total.
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