Shimano R650 calipers

u0362565

Hi all,

I've just purchased some Shimano R650 calipers for my compact road Giant bike to replace the 11year old tektro's that came with the bike. But i didn't really think whether they were compatible with that frame. The front caliper is ok but the rear even when the pad is positioned as high as possible in the caliper arm, the brake pad half sits on the vertical surface of the wheel rim and half not where the wheel curves towards the spokes-its borderline whether enough of the pad is contacting the rim.. Apart from moving the pad to the top of the caliper arm i'm not sure there's anything else i can try to make these fit. Do some bikes need specialist cailpers how do you know whats compatible? I assumed that the R650's would have as much drop as standard calipers and extra (57mm) so not sure if i bought standard drop they'd fit either. Wondering if the fact its a compact road makes it harder to find compatible brakes? What i find odd is that the front caliper fits ok. The bike is a giant ocr1.

I'm wondering if i could return the rear caliper even though i've now tried it on the bike but haven't used it.. And could i use a different model caliper on the front vs rear? Would be nice to have a consistent set so maybe i should take them both both back and try a different brake set. Any recommendations for this bike frame?

Thanks for any advice!

Matthewfalle

If bought as a pair (ie clicked the pair box on the internet shop screen), return as a pair and repurchase front. If you've just bought both at the same time by clicking the front and back buttons then keep the front and send back the rear.

I'm not sure offhand what you need but if you pop into your local Giant shop they will be able to help. Alternatively, can you post a piccies we can see what you mean?

keef66

R650's are long drop calipers. I suspect your frame just needs standard drop brake calipers, so if you're sticking to Shimano that's Tiagra, 105, Ultegra etc depending on your budget.

u0362565

I think I'm probably best returning both the front and rear.they do seem a bit bulky and heavy for a road bike. I've taken them out of the boxes but as long as I have the box and receipt they should take them back. The reason I went for the r650's was because they didn't say there were any restrictions on which STI's they could be used with. The 105's and tiagra's say they cN only be used with certain STI's for the right leverage ratio, although I'm not sure exactly what the significance of that is? If it's referring to the shifters that doesn't matter as this bike is now a single speed, but if it's referring to the actual brake lever I need to be aware of the leverage ratio? How do i identify which model STI levers I have? I'm not sure it says on them.

I'm looking at the ultegra 6700's now any opinions on those? they are compatible with ST7900 and ST6700, perhaps I should go to the shop an ask about all this, thought brakes were simple.

Thanks for the advice!

Matthewfalle

Yup - just stick everything back in the box and send back. Give them a wipe over with a cloth to make sure they are all spankers and job jobbed.

Ref Ultegra - yup, they're fine. Look ok, perform fine. No dramas.

6700 calipers will work perfectly with 6700 shifters if that is what you have.

u0362565

I've switched the brakes for shimano 6700's, got to collect them later this week, hope they fit this time! Apparently the leverage thing isn't a big issue, its just certain brakes are designed for matching brake levers but apparently they will still work. On a related issue, when removing the old brakes i found that the recessed mounting bolts had begun to rust and there was a lot of crap in the hole around the bolt, this isn't surprising considering its proximity to the wheel. i'm surprised though that bikes don't come with some kind of plastic plug that fits behind the bolt to stop dirt and water getting in the hole in the forks. Does something like this exist or do people just leave it as it is? I have to say this is build up over 11 years so perhaps i should just take them off and clean them more often!

Thanks again!

Matthewfalle

They will work fine but may feel a bit wooden. Play and see with the combination you're running.

Re crap: when you put the new ones on, slap a load of copperslip in there to stop it seizing up. If you want, pop a plug in: shouldn't be too hard to find something that fits or just clean it out occasionally. A piece of insulting tape will do the job if you can't find a plug.

u0362565

Ok will do thanks matthew.

bondurant

I stuff the recess with cling film

u0362565

For anyone still listening i've now fitted the brakes and i've blocked off the hole in the front fork where the brake is mounted with part of a silicone ear plug. They're soft and malleable but sturdier than blutak and hopefully will keep water out. Its yet to be seen if it will fall out after a few bumps..

cheers