Brake boss sizes???

[RustyChayne]

I replaced a cheapo suspension fork with a Nashbar chromoly rigid fork and really like the way it feels. Continuing with the upgrades I thought I'd replace the C-Star V brakes with some quality Shimano Deore V brakes BUT this wasn't as easy as I suspected. While my brake bosses are apparently the correct diameter the shouldered portion near the attachment point on the fork is too long or perhaps more precisely the Shimano brake arm is too shallow. Either way they don't fit. The brake arms will not go on the boss far enough before bottoming out to allow the spring tail to go into the hole. I'm aware that there are both 10mm and 8mm bosses but can't seem to find any info or various sizes with regards to the length of the shoulder. There are obviously bosses made that these Shimano brakes will fit unless Shimano is sell these things and people are just putting them in their assorted parts boxes like I did. Does Shimano manufacture a unique brake boss just for their V brakes? The bike world and it's non standardization is maddening sometimes. Any help is greatly appreciated  

[Painkiller]

call Nashbar support. New one on me.

[RustyChayne]

(05-19-2017, 07:42 PM)painkiller Wrote:  call Nashbar support. New one on me.

Chatted online with one of Nashbar's "experts" this morning. Waste of time. I don't think he even understood the problem but said they don't sell brake bosses anyway then told me the fork I bought was an older model and I should just buy a new fork! For what it's worth the Shimano Deore V brakes don't fit on another brand rigid fork either. It's not the forks or the bosses since other brand V brakes work just fine, it is apparently a non standard Shimano dimension, but there must be a matching boss out there somewhere or Shimano wouldn't be selling many of these brakes.

[Painkiller]

something else is going on here. The brakes should fit. Take it to a bike shop have them look at it. If there is anything standardized as far as bicycles go. It is the brake bosses for canti's and V-brakes. Pics may help too if you can load some

[RustyChayne]

(05-19-2017, 11:51 PM)painkiller Wrote:  something else is going on here. The brakes should fit. Take it to a bike shop have them look at it. If there is anything standardized as far as bicycles go. It is the brake bosses for canti's and V-brakes. Pics may help too if you can load some

I hope there is just something I'm missing. I had a couple extra bosses laying around so I made some photos to help visualized the situation. As you can see from the photos the shoulder on the post is at least 2mm longer than the relief in the brake body (the green line versus the yellow line). This extra length keeps the brake body from seating all the way to the flange on the boss and the spring tail is WELL short of the hole it needs to engage. All I can figure is that there are some shorter shouldered bosses out there somewhere. I suppose I can just turn the shoulder back on the lathe since deeper brake arms will work on shorter shoulders but not vice versa. I can't believe in all of bikedom I'm the ONLY PERSON in the universe to experience this

[Painkiller]

I am a bit stumped on this one, Congrats you are only about the second person on here to ever do that! ha. Is it possible to send them back for a refund? I would go with Avid single digit 5 or 7 for replacements. Use them all the time.

[MLM]

(05-20-2017, 11:26 AM)painkiller Wrote:  I am a bit stumped on this one, Congrats you are only about the second person on here to ever do that! ha. Is it possible to send them back for a refund? I would go with Avid single digit 5 or 7 for replacements. Use them all the time.

I have the same problem on a Dahon Mariner D8 the Deore arms have a much shallower recess for the shoulder of the boss.

Any new ideas here?

Thx

[RJD]

Exactly the same problem here but with Avid SD7's not fitting the standard posts, ie the internal recess is not deep enough to clear the shoulder so they stand proud. Looks like shimano/avid have changed the standard or something. Haven't been able to find the correct posts so far other than some expensive titanium ones from ebay/aliexpress which show different 'standard' and 'shimano' posts. Anyone know of a supplier of cheaper steel ones?
Still can't believe there aren't more people coming across this problem, even in these disc brake times.