Does anyone have any tips for preventing Shimano rubberized hoods from permanently stretching when installing them on the shifter?
I’m going to be replacing my bar tape soon and was thinking of buying new hoods too. Unfortunately these hoods have been stretched out like this since I first installed them and never quite fit right in the shifter 
Those seem of same shape as the 11 so GRX mechanical covers. I took care to not heat them but liberally applying hand sanitizer gel to reduce friction. If the rubber is heated it seemed to stretch them easily.
I don’t think you would stretch the rubber permanently on a single installation. That happens over time. I assume you’ve checked the hoods are located properly on the levers - if they aren’t they will not sit flush.
As @Jules mentioned, you’re want to check that the hoods are sitting correctly on the shifter bodies. Shimano’s rubber hoods often have notches and other profiles designed to ensure that the hoods sit right, on the shifter bodies. When misaligned, the profiles can cause the hoods to seem stretched beyond what seems like a normal fit.
Also, though it rarely happens, you can actually stretch the hoods out of shape, if you’re overly ham-fisted. To ease installation, I’ve found that diluted dishwashing detergent helps as a lubricant that can be easily left to dry or removed by wiping with water. The tighter the fit, the greater the concentration of detergent you’d need.
Hope that helps.
Thank you, when I initially installed these I let them sit out in the sun to heat up so I could fit them over the lever. I might have irreparably stretched them by letting them get too warm. I will try the dishwashing soap trick on the next set.
Thanks!
Ah, got it. That makes sense then.
I wouldn’t rely on hearing those hoods (or any synthetic rubber forms, for that matter), unless you have the means of controlling the shape of the item as/when it cools. Otherwise, the different sections of the material would tend to cool at differing rates (for a number of reasons), leading to the situation your hoods are In currently in.
Putting them on from the back stretches the hoods less. You need to disconnect all cables/hoses but it’s worth it.
This is how I replace hoods when my customers request it. I have installed them from the front, with the lever still attached to the bars and find it works fine for the older, slimmer, rim brake levers but the newer disc brake lever hood feel a bit sloppy to me when doing that.
As a few others have mentioned, installing the hoods from the back of the shifter with it taken completely off the bar is much easier, and requires much less aggressive stretching of the material. At the shop I always try to coincide new hoods with brake bleeds/new cables so that I’m not just disconnecting the shifter solely to put the new hood on and having to faff with the cables/hydro lines anyways. IPA in a spray bottle can also help the hood slide on, and is easy to dry with compressed air once the hood is installed.
