specialized bike / bottom bracket specs

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22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

specialized bike / bottom bracket specs

Postby 22camels » 23 Jul 2014, 11:17pm

So I've got a Specialized Tricross Sport 2011 and I've just changed my bottom bracket after the old one started playing up.

Having never changed a BB before, and I wanted to do it myself, I started off by doing some research on which bracket and tools I'd need. I went to the specialized website to look up the spec for my bike: http://www.specialized.com/us/en/bikes/ ... port#specs which can also be found in many other places. I also read a few accounts on forums of others with a tricross changing their BB.

I concluded I have a BB-7420 RPM/Sugino square taper JIS cartridge BB of 68mm shell width and probably 118mm length with a British thread, which they don't seem to make anymore, so I was about to order a Shimano BB-UN55 to replace it.

Then I looked some more. My triple crankset said Tiagra just like in the spec, but it looked like I could only open it from the non-drive side. Well it turned out to be a two-piece crankset which looked just like the FC-4503 in the Tiagra series http://bike.shimano.com/publish/content ... _road.html (OK now I can see there is a FC-4503 label on my crank). And that one is, according to Shimano, only compatible with a Shimano BB-4500 external bearing BB. And indeed my bottom bracket looked just like the BB-4500 (I knew nothing about BB's so it was not obvious to me that it was an external one off the bat).

I ordered a new BB-4600, and an external bracket tool, and the job is now done. Edit: I lucked out, as it turned out I actually had a BB-4500, but the new BB-4600 fit very well too :).

But I am wondering, is it possible that the website spec for some specialized bikes is inaccurate /variable or is the BB/crankset one of those things that's customizable and the bike shop where I got it in 2011 could have fitted a different one? It sounds really dumb but I have no recollection of any discussion of this at the time (though I bought the bike without much thinking in a great hurry), I also don't recall any service afterwards where the BB/crankset were changed!!
Last edited by 22camels on 24 Jul 2014, 12:08am, edited 1 time in total.

22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

Re: specialized bike / bottom bracket specs

Postby 22camels » 23 Jul 2014, 11:51pm

I have to suspect amnesia :). I see no references to Shimano Tiagra FC-4603 Hollowtech II before March 2011 (in fact it may not have become widely available before 2012). I got the bike in Feb 2011… So it must have been changed out as part of a service as I remember asking about the cranks feeling rough..

Edit: OK there is more: I definitely have an FC-4503 crankset which was available before 2011. Indeed it looks just like the image of the bike on the specialized website (though I don't know if you can visually tell different series of Tiagra cranks apart that easily). So my question still stands, if they claim the two piece cranksets like the FC-4503 is compatible only with an external BB like the 4500 (or 4600 as it turns out), how come the spec says it had a cartridge BB-7420 (Sugino)? Or would that have been compatible too, somehow, and I had it changed to an external BB during a service that I'd forgotten about?
Last edited by 22camels on 24 Jul 2014, 12:14am, edited 1 time in total.

OnYourRight
Posts: 283
Joined: 30 Jun 2013, 8:53pm

Re: specialized bike / bottom bracket specs

Postby OnYourRight » 24 Jul 2014, 12:02am

22camels wrote:But I am wondering, is it possible that the website spec for some specialized bikes is inaccurate /variable or is the BB/crankset one of those things that's customizable and the bike shop where I got it in 2011 could have fitted a different one?

Oh, it is all too common for the bike manufacturers to be sloppy with their specs. Half the Dawes specs for my 2012 Clubman were wrong, including the bottom bracket type (claimed external; actual square-taper), tyre type (claimed Rubino; actual Zaffiro), chainset, chain brand, etc.

I suspect this happens in part because these companies are barely making anything anymore, the stuff actually being made in huge factories in Taiwan and the like. In many cases the bikes are probably designed there too. So the left hand doesn’t always know what the right hand is doing. It’s also clear there are often copy-and-paste errors from one list of specs to another, presumably introduced when some lackey is tasked with updating the website for the new model year.

Is it possible your bike has the FC-4503, not the similar but later FC-4603? Tiagra 4500 was introduced in 2007, whereas I think 4600 only arrived in 2012.

22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

Re: specialized bike / bottom bracket specs

Postby 22camels » 24 Jul 2014, 12:21am

Thanks, yes, you're absolutely right. I was going by visual resemblance and figured I had an FC-4603, but there is actually a label on the crank (doh) with FC-4503.. And the BB was a BB-4500. I've edited my post.

I still don't see how they claim the BB on it was a 7420 cartridge BB. What's more it's not just the specialized website but I could see other tricross sport posts on forums talking about replacing the Sugino BB-7420 (though sometimes hard to tell which model year they were).. It may well be that some 2011 tricross sports came with a 7420, but then would the crankset (which looks on their website to be just like an FC-4503) be compatible?

I guess next time I shouldn't trust web specs but examine the physical bike more :).

OnYourRight
Posts: 283
Joined: 30 Jun 2013, 8:53pm

Re: specialized bike / bottom bracket specs

Postby OnYourRight » 24 Jul 2014, 12:38am

If I had to guess, I’d say this particular case was a copy-and-paste error. I say that because the 2010 model does indeed have a square-taper bottom bracket (and matching FSA Tempo chainset). Clearly any bike with a Tiagra 4500 chainset cannot have shipped with a square-taper bottom bracket, no matter what the specs say.

Some of the forum posts might have been referring to that 2010 model (or even earlier), as you surmised. To complicate matters, some of the posters may have bought their 2010 model year bike in 2011.

Many of those Shimano external bottom brackets are officially interchangeable. It wouldn’t even surprise me if the Tiagra 4500 and 4600 bottom brackets are literally identical apart from their model numbers.

22camels wrote:I guess next time I shouldn't trust web specs but examine the physical bike more :).

You and me both! Have a look at the wrong specs for my bike. You got off lightly by comparison.

22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

Re: specialized bike / bottom bracket specs

Postby 22camels » 24 Jul 2014, 1:01am

That looks very likely. And yes, my old 4500 BB and the 4600 I replaced it with, looked the same.

Yes I see yours turned out quite a lot different :)

I wish they made more of an effort given that they publish all these specs in some detail and they are copied by all sorts of retailers and private sellers.. I guess with a BB anyone with half a clue (not me) would immediately be able to tell it's an external one, but next time I might want to service my hubs and where would I find the spec for them (I know nothing about hubs).

tim-b
Posts: 1649
Joined: 10 Oct 2009, 8:20am

Re: specialized bike / bottom bracket specs

Postby tim-b » 24 Jul 2014, 5:54am

Hi
Here's a link to their frame components guide http://service.specialized.com/collateral/ownersguide/new/assets/pdf/Frame---Road-Frame-Compatibility-Guide.pdf
The BB is shown as BSA Std 68mm there too, however it does provide headset and fork details (etc) that I've found accurate for my 2010 Tricross
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

Brucey
Posts: 41454
Joined: 4 Jan 2012, 6:25pm

Re: specialized bike / bottom bracket specs

Postby Brucey » 24 Jul 2014, 7:00am

re specialized hubs; many models use rebranded joytech hubs and the like, given a specialized logo. When they wear out they can be kind of tricky to get the spare parts for. The best thing to do is to carefully adjust and service them regularly.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

Re: specialized bike / bottom bracket specs

Postby 22camels » 24 Jul 2014, 2:12pm

thanks.. yeah I got that frame guide, quite handy but only has partial info..