Ultegra brake caliper

Pritch · 2020-06-03T09:43:51+01:00

Hi I’m hoping somebody will be able to advise me, I need to replace a Shimano RS805 break caliper but I can’t seem to find one online all I seem to find is a R8070. They look identical but can’t find any info to say it’s a compatible replacement, my local bike shop is shut and did normally take it to them. Thank you for any info on this I’ve been looking at videos about replacing it and putting fluid back in so happy to try it myself if it’s the correct part.

This topic has 9 replies, 3 voices, and was last updated 6 years ago by Mathemagician.

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June 3, 2020 at 9:43 am #30790

Pritch

Hi I’m hoping somebody will be able to advise me, I need to replace a Shimano RS805 break caliper but I can’t seem to find one online all I seem to find is a R8070. They look identical but can’t find any info to say it’s a compatible replacement, my local bike shop is shut and did normally take it to them. Thank you for any info on this I’ve been looking at videos about replacing it and putting fluid back in so happy to try it myself if it’s the correct part.
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June 4, 2020 at 11:03 am #960117
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Mathemagician

I’ve been thinking about this

I’ve been thinking about this some more, and did what research I could on it. Here are my thoughts:

Looking at the compatibility chart, every STi lever uses the same sub-brake lever. So that should mean you can connect a BH59 hose and a BH90 hose to the same brake sub lever- it shouldn’t leak or fail or anything.

Reading around, the two hoses have slightly different internal gauges- the BH90 is 0.2 mm narrower, and was developed to give a more progressive feel to the braking.

So if you replace your brake caliper with a 8070 caliper, you should be fine with BH90 hose, however I don’t understand why Shimano’s charts don’t show ST-R785, RS685 and RS505 calipers as compatible. It could just be an oversight? Might be worth emailing Shimano support about it.

June 3, 2020 at 10:06 pm #960115
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Mathemagician

Sorry fella, too busy ranting

Sorry fella, too busy ranting to realise you’d asked a question. Do you know the model of your brake lever? I’m 99.9% certain you’ll be OK though.

June 3, 2020 at 8:52 pm #960113
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Mathemagician

It’s this sort of thing that
It’s this sort of thing that continually pisses me off about Shimano and leaves me baffled as to why so many people think it’s brilliantly engineered stuff…I suppose it is, if you’ve never worked on your own bike before. There’s constant revision going on which makes it nigh on impossible to have a toolkit to cover all bases, these hoses being a perfect example. Another case in point- there are currently THREE different threaded bottom bracket spline sizes, and that’s just for road. Dura Ace requires a different size tool to Ultegra/105, which is different again to Tiagra. Which is a fucking joke.

Rant over. Apologies.

June 3, 2020 at 7:53 pm #960111
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kil0ran

This whole hose thing is very

This whole hose thing is very confusing. Put me off doing a hydro upgrade for my (mostly) Tiagra level tourer as I couldn’t work out which levers worked with which post mount calipers and hose sets.

June 3, 2020 at 4:31 pm #960109
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Pritch

Ok thanks for the reply’s, I

Ok thanks for the reply’s, I’m trying to work this out if the new caliper isn’t compatible with the old hose I need to replace the hose as well but then won’t I have the same issue with the new hose fitting the old break?

June 3, 2020 at 3:04 pm #960107
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Mathemagician

To be certain of

To be certain of compatibility, you could use the 505 caliper, which I’ve found available online:

https://www.bike24.com/p2141813.html?menu=1000,4,322

June 3, 2020 at 1:45 pm #960105
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Mathemagician

Hmm…actually according to

Hmm…actually according to the compatibility charts it won’t work:

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

This is one of those that I’d personally be happy to install it and see, but at the same time I wouldn’t necessarily recommend someone else do that…

June 3, 2020 at 1:39 pm #960103
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Mathemagician

kil0ran wrote:
they do use a different hose kit so that might mean it will be a faff to fit. Need someone with more knowledge of that aspect to help with a bit more detail.

Fitting won’t be an issue, the only thing to look out for is that the two hose types (BH59 and BH90) are slightly different gauges, and hence take slightly different sized inserts. One is gold and the other is silver, so if you remove the hose from the caliper you should be able to see what colour the insert is and buy the same replacement.

In terms of using the R8070 replacement caliper you’ll be fine- connection is still an olive and insert (as opposed to a banjo connection which some of the MTB brakes have moved toward).

June 3, 2020 at 12:55 pm #960101
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kil0ran

I’m not sure because I can’t

I’m not sure because I can’t find them in the line-up/comptability charts here

Looking at the spec pages

https://si.shimano.com/#/

https://bike.shimano.com/en-EU/product/component/ultegra-6800/BR-RS805-R.html

https://bike.shimano.com/en-EU/product/component/ultegra-r8000/BR-R8070-R.html

they do use a different hose kit so that might mean it will be a faff to fit. Need someone with more knowledge of that aspect to help with a bit more detail.

It might be because Shimano’s “RS” range are effectively “non-series” components designed to work with multiple groupset levels.
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