Bicycle Mechanics - will 31.8mm stem work on 31.7mm bars?

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RMMJ

08-08-10, 05:35 AM

Hi. I need a shorter stem. My current stem is a Deda Big Logo 31.7mm. Replacement stems (Ritchie, Forte, Easton) all seems to be 31.8mm. Deda is not sold locally. Will 31.8mm work or am I stuck having to order a Deda? I would have thought that this would be standardized by now. Thanks.

HillRider

08-08-10, 10:27 AM

They are the same diameter. The "true" diameter is 1-1/4" or 31.75 mm. Most makers round the advertised diameter value up to 31.8 mm while Deda rounds down to 31.7 mm.

I always thought this was both misleading and a bit dishonest as it makes you think you need to use their stem too and it's not any different.