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Fitting new chainring.

Old 03-15-19, 11:23 AM
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2wheelride
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Fitting new chainring.

I'm currently working on a bike build and I hadn't realized the chain stay are just wide enough to prevent the new crankset from spinning. I'm wondering if I could fix this with some spacers on the bottom bracket. Could use some help honestly

The chainring is a shimano tiagra double (4500) and the spindle is about 10cm (not including the grooved area for the crank arm. The bottom bracket is a BB RS500 and is 68mm in length and fits the bike snuggly (Kona 2018 Dew)

Last edited by 2wheelride; 03-16-19 at 02:22 PM. Reason: More info
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Old 03-15-19, 11:29 AM
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IDK, without seeing it Supply more details, picture link ? or just take bike to a place that can see it, I cannot ..

Smaller chain ring? Put a dent in the chainstay.. ?







..
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Old 03-15-19, 11:31 AM
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Why don't you start with brand and model of cranks and bottom bracket you're using.

Perhaps upload some phtotos to your Album/Gallery.

https://www.bikeforums.net/g/user/484031

Also some notes about the frame. Frame material? Steel?
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Old 03-15-19, 12:27 PM
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Originally Posted by 2wheelride View Post
I'm currently working on a bike build and I hadn't realized the chain stay are just wide enough to prevent the new crankset from spinning. I'm wondering if I could fix this with some spacers on the bottom bracket. Could use some help honestly
Google 2mm freewheel/bb spacers. They are cheap.
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Old 03-15-19, 02:47 PM
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More info is needed about what frame, crankset and bottom bracket.
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Old 03-16-19, 02:23 PM
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Originally Posted by fietsbob View Post
IDK, without seeing it Supply more details, picture link ? or just take bike to a place that can see it, I cannot ..

Smaller chain ring? Put a dent in the chainstay.. ?







..
I added some more info. Sorry about that.
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Old 03-16-19, 02:24 PM
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I updated the post. Hopefully this helps getting some answers. Thanks
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Old 03-16-19, 02:25 PM
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Originally Posted by dsaul View Post
More info is needed about what frame, crankset and bottom bracket.
I editted the post. Hopefully the information is good.
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Old 03-16-19, 03:17 PM
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BB spacers are fine, you will need ~34mm ID spacers about 3mm thick and could use 1-2 of them between the R cup and the BB shell.
Another possibility for spacers is 1" headtube spacer sets (use only the aluminum ones). Many cranksets come with such spacers for chainline
adjustment. You can put the 1"ID spacers on the crankset shaft to push the crank out further with the BB installed without spacers.
Spacers can be used in either place if they are the right OD/ID.

Spacers supplied with the BB typically to allow same BB to be used in 68 or 73mm BB shells. Limit on spacer # is the fixed length of the
crank axle, so max is ~5-8mm total.

Last edited by sch; 03-16-19 at 04:17 PM.
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Old 03-16-19, 04:05 PM
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Originally Posted by 2wheelride View Post
I'm currently working on a bike build and I hadn't realized the chain stay are just wide enough to prevent the new crankset from spinning. I'm wondering if I could fix this with some spacers on the bottom bracket. Could use some help honestly

The chainring is a shimano tiagra double (4500) and the spindle is about 10cm (not including the grooved area for the crank arm. The bottom bracket is a BB RS500 and is 68mm in length and fits the bike snuggly (Kona 2018 Dew)
I just installed a triple crank using a new BB RS500 bottom bracket. The BB was packaged with 3 spacers and if I remember correctly the instructions stated that 2 of them go on the drive side and 1 on the non drive side.

A local bike shop should have the proper spacers. Installing one or two on the DS should get the small chain ring away from the chain stay.

I installed 1 on the DS and 2 on the NDS - this is the reverse from the instructions but it gave me a better chain line.
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Old 03-17-19, 10:18 AM
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The Tiagra crankset may never fit on your frame. The bike comes with an Altus MTB triple crankset that has a 180mm Q factor, The Tiagra double has a 150mm Q factor, so the arms are probably about 30mm closer together on the Tiagra.(I haven't looked at the framebuilders specs to see the actual distance between the crankarms) Unless the frame was designed for a road double, the Tiagra won't fit.
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