Bike and Mudguard sizing (boardman/SKS)

nirurin Posts: 34
edited September 2014 in Road buying advice
Ok, so I have no ordered my bike, and the bits I need, as I took advantage of an extra 10% off flash offer Halfords had today for a whole 2 hours... was a close thing to get the order in on time lol. ... -bike-2014

However I have now been back in to the local store to test out a couple of things, and to make sure I had the sizings correct etc, before the items arrived and they began to assemble it, in case I needed to make an alteration.

There's two issues, one more important than the other:

1) My size vs Bike frame
I tried the 49cm (medium) Hybrid out in store again (the same bike I tried a few days ago) but this time I was able to properly ride it around a bit with pedals on etc. I could sit astride the frame bar with my feet flat, but there wasnt a huge amount of clearance. The reach to the bars also seems a touch long.
Problem is, I'm used to riding a mountain bike that is too small for me, so it's a tricky one. It will take days to get used to a new bike, and I dont think halfords would let me test it for that long :P

I'm 174cm tall (5 feet, 8.5 inches) with inside leg of 30", so I'm right on the boundary between the "recommended" sizes for the 45cm (17.7") and the 49cm (19.3") frames. I did my "ape index" test and I seem to have a +10cm one... surprisingly Apey, it seems.

Unfortunatly I couldnt test the small as they had none in stock. Though I can change my order and get one in, and test it, and then change my mind.

TLDR: BAsically, both the small and the medium should fit me, though both may require tweaking with saddle position and maybe change the stem. As I seem to be in the middle, is it better to go for the smaller size or the larger?

2) Mudguard vs tyre size
This one should be a lot easier for you guys to help with :smile:
I ordered the following: ... 00c-x-45mm

I got the 45mm width ones, as the smaller 35mm ones maxed out at 28c tyres (which the hybrid has atm), but I was considering that I may change to 32c in the future.

Basically, would 45mm guards be somewhat ridiculous on a 28c wheels?
Or alternatively, would 35mm guards still work on a 32c wheel?

Thanks again guys, You've all been much help. At the moment My thinking is to change my order to the smaller 45cm frame (unless getting a frame slightly too small causes issues im not aware of?) and keeping the 45mm mudguards. The guys at Halfords said the medium bike seemed to be right for me, but I have learnt (from the forums lol) to be wary of advice from Halfords staff :P


  • mercia_man
    mercia_man Posts: 1,431
    It would seem to me that the Halfords advice you have been given that a medium would suit you is best. Looking at the Boardman hybrid sizing chart it does appear you are in the medium category. As you say, it may feel a little stretched because you are currently riding a bike that's too small for you. I suspect the small would be a bit too small for you. But fit on a bike is very personal and it's difficult to give useful advice online.

    On the mudguards, I can be more positive. I use SKS 35mm guards with 28mm tyres on my touring bike and they are a good snug fit and look appropriate. I have also used them with 32mm tyres. It is doable but the clearances are tight and you may have problems with the tyre scraping the edge of the guards if you go through mud, for example. You may also get a bit of rub between guard and tyre when the rear wheel flexes as you are honking uphill. Also, there can be a lot of variation in the size of nominally 32mm tyres.

    The 45mm guards do look a bit wide on narrower tyres but the extra width does give you and the bike better protection from the rain. SKS do a slightly narrower guard (I think in 40 or 42) under the Bluemels name with a rounder profile. This doesn't look quite so wide with narrow tyres and is a better fit for size 32 tyres.

    One thing to bear in mind is the clearance under the fork crown. SKS narrow 35 guards fit fine under mine. But I have to cut away the side of wider guards to get them to fit. However, looking at the pix of the Boardman hybrid, I think those forks provide quite a lot of clearance.
  • Yeh I think the boardman has clearance for 45mm....
    There is one make of sks guard that has a middle size, but halfords don't sell it and I get 30% off at the moment. If the 45 looks wrong or won't fit I can always exchange before I cut anything.

    I measured my current bike last night, and it's a 22" frame on 26" wheels, which guides say is for 6'1 and above (wtf) but the stand over seems about the same, maybe an inch lower, than the medium boardman. So maybe the stand over was on.

    The top tube on my current bike is only 53 cm though. The medium boardman is 59, and the small is 56.5, so they'll both be bigger. I think it's just a totally different geometry to what I'm used to, so I may stick with medium and then move the seat forward and maybe shorten the stem (if these things are needed)